JP2007110010A - Flexible printed wiring board, flexible printed circuit board, and their manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a flexible printed wiring board which can effectively dissipate heat of a mounted semiconductor chip, is excellent in shielding against electromagnetic waves, is highly flexible, is inexpensive in material cost for preparing a flexible printed circuit board with good assembling operability when in use, is easy to produce with a small number of manufacturing processes, does not need an expensive apparatus, and can provide wiring patterns on multiple layers or on both surfaces. <P>SOLUTION: The manufacturing method includes steps of laminating an epoxy-based resin sheet made of thermosetting resin for example on a metallic base material 50 made of copper, aluminum or the like, and applying heat and pressure to form an insulation material 52 serving as an adhesive; forming a wiring pattern 53a thereon via the insulation material; then applying heat and pressure to a ground wiring part of the wiring pattern by pressing a bonding tool 56 or the like against the part; burying the ground wiring in the softened insulation material 52 by deforming the wiring; and connecting it with the metallic base material 50. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flexible printed wiring board that forms a conductor pattern by printing on a flexible short or long sheet substrate. And it is related with the flexible circuit board which mounts a semiconductor chip on such a flexible printed wiring board. The present invention also relates to a method for manufacturing the flexible printed wiring board and the flexible circuit board.

  A conventional flexible circuit board is configured as shown in FIG. Reference numeral 1 in the figure denotes an insulating base material, on which a wiring pattern 2 is formed, and the wiring pattern 2 is covered with a solder resist 3 to be protected, and the bumps of the semiconductor chip 4 are bumped on the chip connection terminals 2a of the wiring pattern 2. 5, the semiconductor chip 4 was flip-chip mounted on the insulating base material 1, and the sealing resin 6 was filled between the insulating base material 1 and the semiconductor chip 4 for resin sealing.

  FIG. 11B shows a usage example of the semiconductor module 7 formed by punching from the flexible circuit board. As shown in the figure, the semiconductor module 7 is curved with the side on which the semiconductor chip 4 is mounted as the inside, and for example, another partial connection terminal 2b of the wiring pattern 2 is connected to the liquid crystal panel 8 and another other connection terminal 2c. Is connected to another printed wiring board 9.

  By the way, in such a semiconductor module 7, heat is generated in the semiconductor chip 4 by use. The heat generated in the semiconductor chip 4 is transmitted to the air around the semiconductor chip 4, and is transmitted to the wiring pattern 2 and the sealing resin 6 directly in contact with the semiconductor chip 4, and further connected to them. It is transmitted to the parts that are in order. Then, heat is radiated to the surrounding air one after another through those components connected directly or indirectly to the semiconductor chip 4.

Here, regarding heat conduction, there is a Fourier law, where θ is a thermal resistance, L is a path length, λ is a thermal conductivity, and A is a heat transfer area.
θ = L / λ · A
The following equation holds. Of course, the smaller the thermal resistance θ, the easier the heat is transmitted and the temperature of the heating element can be lowered.

  Therefore, as can be seen from the Fourier law, in the conventional semiconductor module 7 as shown in FIG. 11, the semiconductor chip 4 is small, and the sealing resin 6 directly or indirectly connected to the semiconductor chip 4 Since the thermal conductivity λ of the insulating base material 1 is also small, it was not possible to expect a heat dissipation effect. In particular, with recent increases in the density and definition of liquid crystal screens, the wiring pattern 2 is thinned and thinned, and heat dissipation through the wiring pattern 2 tends to deteriorate.

  As a result, the heat generated in the semiconductor chip 4 is less likely to be lowered, causing problems such as a reduction in the operation speed of the semiconductor chip 4 and a decrease in reliability.

  In such a semiconductor module 7, the insulating substrate 1 needs to withstand heat and chemicals received during the manufacturing process, and polyimide is usually used. However, since polyimide is expensive and its manufacturer is limited, there is a problem that supply is uneasy. Further, there are problems that it is difficult to recycle and it is difficult to meet today's demands for environmental protection, and it is very easy to be charged, dust and foreign matter are easily adsorbed, and there are concerns about adverse effects on the semiconductor chip 4.

  Further, even when it is bent as shown in FIG. 11 (B) in use, the insulating base material 1 made of polyimide is not easily plastically deformed and still retains elasticity, so that a force to return to the original shape works. As a result of today's miniaturization, high density, and high definition, there has been a problem that the work efficiency is lowered particularly when mounting in a narrow and complex space. In addition, the electromagnetic wave generated from the wiring pattern 2 may adversely affect another wiring pattern 2 or may adversely affect the outside, and conversely, may be affected by the electromagnetic wave from the outside.

  Therefore, in the conventional flexible printed circuit board, in order to enhance the heat dissipation effect of the semiconductor chip, the semiconductor chip is mounted on the flexible printed wiring board formed by the manufacturing method shown in FIG. 12 as shown in FIG. There is something to form. Then, a semiconductor module formed by punching from the flexible printed circuit board has been used, for example, as shown in FIG.

  That is, as shown in FIG. 12 (A), for example, a double-sided wiring base material 28 having a wiring forming copper foil 11 on one side of a long insulating base material 10 and a solid copper foil 12 on the other side, As shown in (B), a part of the solid copper foil 12 of the double-sided wiring substrate 28 is removed in a round shape to form a circular removal portion 12a, and then, as shown in (C) by chemical etching or laser irradiation. A part of the insulating base material 10 was removed to form the insulating base material removal portion 10a. Here, when forming the insulating base material removal part 10a by laser irradiation, it is necessary to perform a desmear treatment by a chemical etching method because smear remains behind the wiring forming copper foil 11 without being completely removed, Further, it was necessary to perform conductivity imparting treatment for electrolytic plating treatment to be performed later.

  Next, as shown in (D), the insulating base material removing portion 10a is subjected to electrolytic plating, the copper plating 13 is attached, the wiring forming copper foil 11 and the solid copper foil 12 are connected, and the blind via hole 14 is formed. Thereafter, as shown in (E), the wiring forming copper foil 11 is etched to form a wiring pattern 11a in which the ground wiring portion is connected to the copper plating 13, and the wiring pattern 11a is subjected to tin plating or gold plating. The solder resist 15 was provided and the flexible printed wiring board 16 was formed.

  Thereafter, as shown in FIG. 13A, the flexible printed wiring board 16 is provided so as to be transportable in the length direction, and is sequentially placed on the heating stage 17, and the semiconductor chip 18 is placed on the chip connection terminal 11b of the wiring pattern 11a. The gold bumps 19 are aligned, heated and pressed by the bonding tool 20 to connect them, and the semiconductor chip 18 is mounted on the flexible printed wiring board 16 by flip chip mounting. Then, as shown in (B), the sealing resin 22 was poured using the coating nozzle 21, and the semiconductor chip 18 was sealed as shown in (C) to complete the flexible printed circuit board 23.

  When used, the semiconductor module 26 is formed by punching from the long flexible printed circuit board 23 on which the semiconductor chips 18 are mounted at regular intervals, and the semiconductor module 26 is similarly formed as shown in FIG. For example, another partial connection terminal 11 c of the wiring pattern 11 a is connected to the liquid crystal panel 24, and another other connection terminal 11 d is connected to another printed wiring board 25.

  As a result, the heat generated by the semiconductor chip 18 is transmitted from the gold bump 19 to the wiring pattern 11 a, and is transmitted from the wiring pattern 11 a to the solid copper foil 12 having a large surface area via the copper plating 13. Here, considering the Fourier law described above, the gold bump 19, the wiring pattern 11 a, the copper plating 13, and the solid copper foil 12 on the path all have large thermal conductivity λ, and the heat transfer of the solid copper foil 12. Since the area A is also large, the thermal resistance θ can be reduced and the heat dissipation effect of the semiconductor chip 17 can be increased.

  Moreover, in the semiconductor module 26 as shown in the figure, the ground wiring portion of the wiring pattern 11a is connected to the solid copper foil 12, so that the solid copper foil 12 provided on the entire back surface side of the insulating base 10 produces an electromagnetic wave shielding effect, Electromagnetic noise generated from the pattern 11a can be reduced, and the influence of external electromagnetic noise can be reduced. Furthermore, as shown in FIG. 14, when the semiconductor module 26 is bent and assembled, the solid copper foil 12 is plastically deformed to reduce the elastic force to return to the original shape, so that the assembling workability can be improved. There is also.

  However, in the manufacturing method as shown in FIGS. 12 and 13, the expensive double-sided wiring substrate 28 is used, the number of manufacturing steps is large, and chemical etching is performed to remove a part of the insulating substrate 10. Since an expensive device such as a device or a laser irradiation device is required, there is a problem in terms of cost and cost. In addition, there is a problem that it is difficult to provide wiring patterns on the insulating base material 10 in multiple layers and to provide wiring patterns on both surfaces of the insulating base material 10.

  In addition, the conventional flexible printed wiring board does not use an expensive double-sided wiring substrate, has a relatively small number of manufacturing steps, and does not require an expensive apparatus such as a chemical etching apparatus or a laser irradiation apparatus. In addition, a manufacturing method in which wiring patterns can be provided in multiple layers or on both sides has also been proposed.

  For example, as shown in FIG. 15A, the surface of the metal plate 30 is covered with an insulating material 31, and a copper paste is screen-printed on the insulating material 31 as shown in FIG. Thus, the wiring pattern 32 is formed.

  When forming a two-layer circuit, the insulating layer 33 is formed by applying a photosensitive resin on the insulating material 31 so as to cover the wiring pattern 32 as shown in FIG. Thereafter, exposure and development are performed through a mask to form a pattern of the insulating layer 33 as shown in (D), and a copper paste 34 is embedded and hardened in the recess of the insulating layer 33 as shown in (E). Thereafter, the above steps (B) to (D) are repeated to form the second wiring pattern 35, and then the second insulating layer 36 is formed. As shown in FIG. Nickel plating and gold plating 37 are applied to obtain a flexible printed wiring board.

  According to the flexible printed wiring board produced by the manufacturing method shown in FIG. 15, since the metal plate 30 that is easily plastically deformed and easily bent is used, the workability at the time of assembly can be improved. However, since the wiring patterns 32 and 35 are not connected to the metal plate 30, it was not possible to expect an essential heat dissipation effect.

  As if the first-layer wiring pattern 32 and the second-layer wiring pattern 35 were connected using the copper paste 34, the copper paste was formed by screen printing to connect the metal plate 30 and the wiring pattern 32. However, in printing, it is not possible to form a fine wiring pitch, and it must be printed in a vacuum state so as not to confine air, and then it must be cured, which requires a very large number of steps. To do. Further, when the photosensitive resin is used for forming the insulating layers 33 and 36, there are many problems such as poor electrical insulation characteristics and high warpage due to high thermal shrinkage.

  Further, in the conventional flexible printed wiring board, as indicated by reference numeral 40 in FIG. 16A, a metal circuit pattern 42 is formed on the base film 41, and the metal circuit pattern 42 is heated. The plastic circuit 43 is provided to align the metal circuit pattern 42 with the copper foil pattern 46 on the substrate 45 of the printed wiring board 44, and as shown in FIG. Some are more easily connected.

  However, in such a flexible printed wiring board, even if the base plate 45 of the printed wiring board 44 is used as a metal base to improve the heat dissipation effect, the base film 41 is present, so that the semiconductor chip is connected to the metal circuit pattern 42. It is difficult to connect the metal circuit patterns 42 to each other even if they are formed in multiple layers. Further, since the chip 48 of the ultrasonic horn 47 is used to push through the base film 41, the small area of the metal circuit pattern 42 cannot be pushed, and only one wiring of the metal circuit pattern 42 is pushed to cope with it. There was a problem that it was difficult to connect to the copper foil pattern 46.

Japanese Patent Laid-Open No. 2-177493 JP-A-4-186977

  As described above, manufacturing can produce a flexible printed circuit board that can effectively dissipate the heat generated by the mounted semiconductor chip, has excellent electromagnetic shielding properties, is flexible, and has good assembly workability during use. In the method, an expensive double-sided wiring substrate is used, the number of manufacturing processes is large, and an expensive device such as a chemical etching device or a laser irradiation device is required to remove a part of the insulating substrate. There was a problem in terms of cost effectiveness due to high costs. In addition, there is a problem that it is difficult to provide wiring patterns on the insulating base material in multiple layers and to provide the wiring patterns on both surfaces of the insulating base material.

  SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a flexible printed circuit that can effectively dissipate heat of a semiconductor chip to be mounted, has excellent electromagnetic shielding properties, is highly flexible, and has good assembly workability during use. Providing a flexible printed wiring board manufacturing method that can be used to create a board with low material costs, few manufacturing steps, easy manufacturing, and without the need for expensive equipment, and providing wiring patterns on multiple layers and on both sides. There is to do.

  A second object of the present invention is to create a flexible printed circuit board that improves the reliability of the connection between the ground wiring portion of the wiring pattern and the metal substrate, and further improves the heat dissipation effect by ensuring the heat dissipation of the semiconductor chip. An object of the present invention is to provide a method for producing a flexible printed wiring board that can be made.

  A third object of the present invention is to provide a method of manufacturing a flexible printed wiring board having a complicated circuit configuration by increasing the number of wiring patterns.

  A fourth object of the present invention is to provide a method for manufacturing a flexible printed wiring board having a complicated circuit configuration by making the wiring pattern double-sided.

  A fifth object of the present invention is a flexible printed circuit which can effectively dissipate heat generated by a semiconductor chip to be mounted, is excellent in electromagnetic wave shielding, is rich in flexibility, and has good assembling workability during use. The object is to provide a flexible printed wiring board capable of producing a board.

  A sixth object of the present invention is a flexible printed circuit that can effectively dissipate heat generated by a semiconductor chip to be mounted, has excellent electromagnetic shielding properties, is highly flexible, and has good assembly workability during use. Providing a method for manufacturing flexible printed circuit boards that can produce boards with low material costs, few manufacturing processes, easy manufacturing, and without the need for expensive equipment, and can be provided with wiring patterns on multiple layers or on both sides. There is to do.

  A seventh object of the present invention is to provide a flexible printed circuit that can effectively dissipate heat generated by a semiconductor chip to be mounted, has excellent electromagnetic shielding properties, is highly flexible, and has good assembling workability during use. It is to provide a flexible printed circuit board capable of producing a board.

Therefore, the invention according to claim 1 is related to a method for manufacturing a flexible printed wiring board, and in order to achieve the first object described above,
Insulation that is an adhesive by laminating, for example, an epoxy resin sheet, which is a thermosetting resin, on a short or long flexible sheet-like metal substrate made of copper, aluminum, or the like by applying heat and pressure. After forming a wiring pattern by providing, for example, copper foil laminating, photoresist coating, exposure, development, etching resist coating, etching, etching resist removal through the insulating material,
Heat and pressure are applied to the ground wiring part of the wiring pattern by pressing a bonding tool, etc., and the ground wiring part is deformed to be buried in the insulating material softened by heat and connected to the metal substrate. To
It is characterized by that.

  When the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is released to the metal base material to which the ground wiring portion is connected via the wiring pattern.

  According to a second aspect of the present invention, in order to achieve the second object described above, in the method of manufacturing a flexible printed wiring board according to the first aspect, heat and pressure are applied to the ground wiring portion and ultrasonic vibration is applied. It is characterized by adding.

  And, when connecting the ground wiring part of the wiring pattern to the metal substrate, by applying heat and pressure to the ground wiring part using a bonding tool etc., and simultaneously applying ultrasonic vibration, the ground wiring part is deformed. It is buried in an insulating material and applied to a metal substrate, and they are metal-welded.

The invention according to claim 3 is the method for producing a flexible printed wiring board according to claim 1 or 2, in order to achieve the third object described above.
After forming the second wiring pattern on the wiring pattern via the second insulating material,
Heat and pressure are applied to the second wiring pattern by pressing a bonding tool, etc., and the second wiring pattern is deformed to be buried in the second insulating material and connected to the wiring pattern.
It is characterized by that.

  Then, when the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is guided to the first wiring pattern through the second wiring pattern, and the ground wiring is connected through the first wiring pattern. Relief to the metal substrate to which the part connects.

The invention according to claim 4 is the method for producing a flexible printed wiring board according to claim 3, in order to achieve the third object described above.
After forming the upper layer wiring pattern via the upper layer insulating material on the lower layer wiring pattern,
Heat and pressure are applied to the upper wiring pattern, and the upper wiring pattern is deformed so as to be buried in the upper insulating material and connected to the lower wiring pattern to provide a multilayer wiring pattern.
It is characterized by that.

  Then, when the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is sequentially guided to the lower layer wiring pattern through the upper layer wiring pattern, and the first layer wiring pattern is formed through the multilayer wiring pattern. Escape to the metal substrate to which the ground wiring part connects.

The invention according to claim 5 is the method for manufacturing a flexible printed wiring board according to any one of claims 1 to 4, in order to achieve the fourth object described above.
While forming the front side wiring pattern through the front side insulating material on the surface of the metal base material, after forming the back side wiring pattern through the back side insulating material on the back side,
Heat and pressure are applied to the ground wiring portions of the front side and back side wiring patterns, and the ground wiring portions are deformed to be buried in the front side or back side insulating material, respectively, so that Connecting,
It is characterized by that.

  When the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is released to the metal base material to which the ground wiring part is connected via the front side wiring pattern, and the heat released to the metal base material is released. It is also transmitted to the back side wiring pattern through the ground wiring portion of the back side wiring pattern.

  The invention according to claim 6 is applied to the flexible printed wiring board, and is formed by the manufacturing method according to any one of claims 1 to 5 in order to achieve the fifth object described above. .

  A seventh aspect of the invention relates to a method for manufacturing a flexible printed circuit board, and a semiconductor chip is mounted on the flexible printed wiring board according to the sixth aspect of the invention in order to achieve the sixth object described above. Features.

  According to an eighth aspect of the present invention, there is provided a flexible printed circuit board, wherein the flexible printed circuit board is formed by the manufacturing method according to the seventh aspect to achieve the seventh object.

  Therefore, according to the invention described in claim 1, since expensive materials such as a double-sided wiring substrate are not used, the material cost is low, the number of manufacturing steps is relatively small, and the manufacturing is easy. An expensive apparatus such as a laser irradiation apparatus is not required, and a method for manufacturing a flexible printed wiring board in which wiring patterns can be provided on multiple layers or on both surfaces can be provided. The flexible printed wiring board manufactured according to the present invention is called a microstrip structure, and the characteristic impedance is controlled by setting the dielectric constant of the insulating material, the thickness of the insulating material, and the width and thickness of the wiring pattern. It is possible.

  When the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is released to the metal base material to which the ground wiring portion is connected via the wiring pattern, so that the heat of the mounted semiconductor chip is effectively dissipated. In addition, since a metal substrate is used, it is possible to produce a flexible printed circuit board that is excellent in electromagnetic wave shielding properties and has high flexibility and good assembly workability during use.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, when connecting the ground wiring portion of the wiring pattern to the metal substrate, heat and pressure are applied to the ground wiring portion. In addition, ultrasonic vibration is applied and the ground wiring part is deformed so that it is applied to the metal substrate and welded to the metal, thus providing a highly reliable electrical and mechanical connection and heat dissipation of the semiconductor chip. It is possible to provide a method for manufacturing a flexible printed wiring board capable of producing a flexible printed circuit board having a further improved heat dissipation effect.

  According to the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, when the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is transmitted via the second wiring pattern. Lead to the first layer wiring pattern and escape to the metal substrate to which the ground wiring part is connected via the first layer wiring pattern, so the wiring pattern can be made two layers and flexible with a complicated circuit configuration A method for manufacturing a printed wiring board can be provided.

  According to the invention described in claim 4, in addition to the effect of the invention described in claim 1 or 2, when the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is transmitted via the upper wiring pattern. In turn, it leads to the lower layer wiring pattern and escapes to the metal substrate to which the ground wiring portion of the first layer wiring pattern is connected via the multilayer wiring pattern, so that the wiring pattern is multilayered and a more complicated circuit configuration is achieved. The manufacturing method of the flexible printed wiring board which has can be provided.

  According to the invention of claim 5, in addition to the effect of the invention of any one of claims 1 to 4, when the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is transferred to the front-side wiring pattern. Since the heat is released to the metal substrate to which the ground wiring part is connected via the backside wiring pattern to the backside wiring pattern through the ground wiring part of the backside wiring pattern, the heat dissipation effect of the semiconductor chip is transmitted. Furthermore, it is possible to provide a method for manufacturing a flexible printed wiring board having a complicated circuit configuration by increasing the number of both sides of the wiring pattern and increasing the number of wiring patterns.

  According to the invention of claim 6, since it is formed on the flexible printed wiring board and formed by the manufacturing method according to any one of claims 1 to 5, when the semiconductor chip is mounted by flip chip connection, Since the generated heat is released to the metal base material to which the ground wiring part is connected via the wiring pattern, the heat generated by the semiconductor chip to be mounted can be effectively dissipated, and since the metal base material is used, the electromagnetic wave In addition, it is possible to provide a flexible printed wiring board capable of producing a flexible printed circuit board that is excellent in shielding property and has good flexibility and good assembly workability during use. The flexible printed wiring board according to the present invention is called a microstrip structure. Similarly, by setting the dielectric constant of the insulating material, the thickness of the insulating material, and the width and thickness of the wiring pattern, the characteristic impedance can be reduced. It is possible to control.

  According to the invention described in claim 7, since the semiconductor chip is mounted on the flexible printed circuit board according to claim 6, an expensive material such as a double-sided wiring base material is used. The material cost is low, the number of manufacturing steps is relatively small, and the manufacturing is easy. Moreover, an expensive device such as a chemical etching device or a laser irradiation device is not required, and wiring patterns can be provided on multiple layers or both sides. A method for manufacturing a flexible printed circuit board can be provided. The flexible printed circuit board manufactured according to the present invention is called a microstrip structure, and the characteristic impedance can be controlled similarly.

  And since the heat generated by the semiconductor chip is released to the metal base material to which the ground wiring portion is connected via the wiring pattern, the heat of the semiconductor chip to be mounted can be effectively dissipated, and the metal base material is used. Therefore, it is possible to produce a flexible printed circuit board that has excellent electromagnetic wave shielding properties and is also flexible and has good assembly workability during use.

  According to the invention described in claim 8, since it is applied to the flexible printed circuit board and formed by the manufacturing method according to claim 7, the ground wiring portion connects the heat generated by the semiconductor chip via the wiring pattern. Because it escapes to the metal base, it can effectively dissipate the heat generated by the semiconductor chip to be mounted, and since it uses a metal base, it excels in electromagnetic wave shielding, and in addition, it has excellent flexibility and A flexible printed circuit board with good assembly workability can be provided. The flexible printed circuit board according to the present invention is called a microstrip structure, and can similarly control the characteristic impedance.

The best mode for carrying out the present invention will be described below with reference to the drawings.
1A to 1D show a manufacturing process of a flexible printed wiring board according to the present invention.

  When forming the flexible printed wiring board according to the present invention, a metal substrate 50 is used as shown in FIG. The metal substrate 50 is made of copper, aluminum, or the like, and may be short. However, in the illustrated example, a long flexible sheet-like material is used, and it has an appropriate strength and easily deforms plastically when bent. Use a metal composition with Considering the ease of bending, it is better to be thin, but considering the ease of manufacturing, strength is also required, and a thickness of 10 to 300 μm, preferably 10 to 100 μm is used.

  When a wiring pattern is formed only on one side of the metal base material 50, a warp prevention material 51 may be attached to the back surface of the metal base material 50 as indicated by a virtual line in the drawing. As the warp preventing material 51, an epoxy resin sheet that is a thermosetting resin that is substantially the same in thermal shrinkage rate as that of an insulating material 52 described later, for example, the same as that used for the insulating material 52 described later, is used. After being laminated on the back surface of the metal substrate 50, it is heated and cured in advance so as not to be softened in a later step.

  An insulating material 52 that also functions as an adhesive is provided on the surface of the metal substrate 50. The insulating material 52 is formed by laminating an epoxy resin sheet, which is a thermosetting resin in a semi-cured state (so-called B stage), by applying heat and pressure. As another method, the liquid insulating material 52 may be applied by a roll coater. After forming in this way, the temperature and time of the heat treatment applied to the insulating material 52 are adjusted, and heat can be applied again to make it softer. For example, a material that is solid at room temperature to 100 ° C., softens when heated to 100 ° C. or higher, and further cures when heated to a thermosetting reaction.

  The insulating material 52 has a thickness of 1 to 50 μm, preferably 2 to 20 μm. It is also possible to use thermoplastic resin instead of thermosetting by adjusting the connection conditions of the semiconductor chip described later. As the thermoplastic resin, an acrylic resin, a modified polyimide, a thermoplastic polyimide, a liquid crystal polymer, and the like are preferable.

  On such an insulating material 52, a wiring forming copper foil 53 having a thickness of 5 to 25 μm is laminated to form a metal base substrate material 54 as a whole. Then, after a photoresist is applied to the surface of the wiring forming copper foil 53, development is performed after exposure at regular intervals while being conveyed in the length direction. Then, except when laminating the warp prevention material 51, by applying an etching resist on the back surface of the metal substrate 50, etching is performed, and then the photoresist and the etching resist are removed using an alkaline solution or the like, As shown in FIG. 1B, the same wiring pattern 53a is formed at regular intervals using a known process.

  Next, as shown in FIG. 1 (C), while being transported in the length direction, the bonding tools 56 set in order on the anvil 55 and heated to a predetermined temperature are aligned for each individual wiring pattern 53a. Then, it is pressed against the ground wiring portion of each wiring pattern 53a to apply heat and pressure. Thereby, as time passes, heat of the bonding tool 56 is transmitted through the wiring pattern 53a to soften the insulating material 52, and by deforming the wiring pattern 53a, the metal base material 50 is buried in the insulating material 52. Connect to.

  When heat and pressure are applied to the ground wiring portion using the bonding tool 56, ultrasonic vibration may be applied at the same time. In this case, the ground wiring portion of the wiring pattern 53a and the metal substrate 50 are welded to each other. Thus, a highly reliable connection can be made both electrically and mechanically.

  And after connecting the ground wiring part of the wiring pattern 53a and the metal substrate 50 as described above, when using a thermosetting resin as the insulating material 52, the whole is heated to cure the insulating material 52. To cure completely. When a thermoplastic resin is used, the entire heating is not performed.

  By the way, when the connection purpose between the ground wiring portion of the wiring pattern 53a and the metal substrate 50 is one that does not require electrical continuity and merely requires thermal conduction, the bonding tool 56 is subjected to ultrasonic vibration. Only heat and pressure should be applied. At this time, after connecting the ground wiring portion and the metal base material 50 and then releasing the bonding tool 56, the temperature of the insulating material 52 around the connecting portion decreases, and the insulating material 52 around the connecting portion is cured and the line is removed. Shrink according to the expansion coefficient. As a result, a force that constantly presses the ground wiring portion and the metal base 50 is applied to the connecting portion.

  Next, in order to improve the electrical connection with the semiconductor chip and enhance the rust prevention effect, tin plating, gold plating, nickel underplating gold, indium plating is applied to the back surface of the wiring pattern 53a and the metal substrate 50. Perform metal plating. Also, before and after the metal plating, in order to protect the wiring pattern 53a as required, printing is performed on the wiring pattern 53a except for the chip connection terminal 53b and other connection terminal portions as shown in FIG. Thus, a flexible printed wiring board 58 is formed by providing a solder resist 57 having excellent flexibility.

  According to such a manufacturing method of the flexible printed wiring board 58, since an expensive material such as a double-sided wiring substrate is not used, the material cost is low, the number of manufacturing steps is relatively small, and the manufacturing is easy. An expensive device such as a device or a laser irradiation device is not required, and wiring patterns can be provided on multiple layers or both surfaces. The formed flexible printed wiring board 58 is called a microstrip structure, and the characteristic impedance is set by setting the dielectric constant of the insulating material 52, the thickness of the insulating material 52, and the width and thickness of the wiring pattern 53a. Can be controlled.

  2A to 2C show a manufacturing process for forming the flexible printed circuit board 60 according to the present invention using the flexible printed wiring board 58 formed by the manufacturing process of FIG.

  As shown in FIG. 2A, a flexible printed wiring board 58 is provided so as to be transportable in the length direction, sequentially set on a heating stage 61 set at a predetermined temperature, and a bonding tool 62 set at a predetermined temperature. The metal bump 64 formed by gold plating on the semiconductor chip 63 is lowered while being aligned with the chip connection terminal 53b of the wiring pattern 53a, and pressure is applied with heat through the semiconductor chip 63. In addition, the metal bump 64 and the chip connection terminal 53b are connected by Au—Sn eutectic bonding.

  When a thermoplastic resin is used for the insulating material 52, if the time during which pressure is applied together with the heat through the semiconductor chip 63 is lengthened, the insulating material 52 is softened by the transmitted heat and the chip connection terminal 53b becomes the insulating material. Therefore, the bonding tool 62 is adjusted to rise when it is slightly buried.

  Then, as shown in FIG. 2B, the sealing resin 66 is applied so as to draw the periphery along the side surface of the semiconductor chip 63 using the application nozzle 65, and injected by capillary action to form the insulating material 52. It fills between the semiconductor chips 63. Then, as shown in (C), the sealing resin 66 is thermally cured to seal the semiconductor chip 63 with resin, and the flexible printed circuit board 60 is completed.

  When used, a semiconductor module 67 is formed by punching out a long flexible flexible printed circuit board 60 on which semiconductor chips 63 are mounted at regular intervals into a predetermined shape for each unit including each semiconductor chip 63. The module 67 is curved with the side on which the semiconductor chip 63 is mounted as shown in FIG. 3, for example, another partial connection terminal 53c of the wiring pattern 53a is connected to the liquid crystal panel 68, and another other connection terminal 53d. Is connected to another printed wiring board 69.

  With such a flexible printed circuit board 60, heat generated by the semiconductor chip 63 is released from the metal bumps 64 to the metal substrate 50 to which the ground wiring portion is connected via the wiring pattern 53a. The heat of 63 can be efficiently transmitted through the metal bumps 64 and the wiring pattern 53a with good thermal conductivity, and can be effectively dissipated from the wide metal base material 50 with good thermal conductivity to the surrounding space. As a result, it is possible to eliminate the possibility that the operation speed of the semiconductor chip 63 is lowered or the reliability of the semiconductor chip 63 is lowered.

  In addition, since the metal substrate 50 is used by electrically connecting the ground wiring portions of the wiring pattern 53a, the electromagnetic shielding performance is excellent, electromagnetic noise generated from the wiring pattern 53a is reduced, and electromagnetic noise from the outside is also provided. Can be less affected by In addition, it is highly flexible, and when the semiconductor module 67 is bent and assembled as shown in FIG. 3, the elastic force of the metal base 50 to plastically deform and return to its original shape is reduced. As a result, it is often bent and assembled in the housing, and the assembling workability in such a case can be improved.

  When the ground wiring portion of the wiring pattern 53a is connected to the metal base material 50, heat and pressure are applied to the ground wiring portion and ultrasonic vibration is applied, so that the ground wiring portion and the metal base material 50 are metal-welded. When the flexible printed circuit board 60 is formed by using the printed wiring board 58, it is possible to make a highly reliable connection both electrically and mechanically, to ensure heat dissipation of the semiconductor chip 63, and to further improve the heat dissipation effect. it can.

  4A to 4D show a manufacturing process of a two-layer flexible printed wiring board according to the present invention.

  In the manufacturing process of the illustrated two-layer flexible printed wiring board, first, the wiring pattern 53a is formed on the metal substrate 50 through the insulating material 52 through the manufacturing process similar to that shown in FIGS. Then, the ground wiring portion of the wiring pattern 53 a is connected to the metal substrate 50. Thereafter, a second insulating material 70 having a thickness of 1 to 50 μm, preferably 2 to 20 μm, and a second wiring forming copper foil 71 are laminated on the wiring pattern 53a.

  In the case of this example, a thermosetting resin is used for the first-layer insulating material 52, and a thermoplastic resin is not used. If a thermoplastic resin is used for the first-layer insulating material 52, the lower wiring pattern 53a is also buried by heat applied during connection between the second wiring pattern 71a and the wiring pattern 53a, which will be described later, and an appropriate connection is made. Because it becomes impossible.

  For example, as shown in FIG. 5, the second insulating material 70 and the second wiring forming copper foil 71 are obtained by applying the second insulating material 70 to the second wiring forming copper foil 71 while being conveyed in the direction of the arrow. Is laminated using a laminating roller 72 heated to a predetermined temperature while being heated and pressurized. At this time, a recess 73 is formed in the connection portion between the wiring pattern 53a and the metal substrate 50, and it is preferable to use a vacuum laminator so that no air accumulation occurs in the recess 73.

  Or, for example, as shown in FIG. 6 (A), a film obtained by applying the second insulating material 70 to the cover film 74 while being conveyed in the direction of the arrow is heated together with a laminating roller 72 heated to a predetermined temperature. Laminate while pressing. Also in this case, it is preferable to use a vacuum laminator for the same reason. Thereafter, as shown in FIG. 6B, the second wiring forming copper foil 71 is continuously used by heating the laminating roller 72 while peeling the cover film 74 while similarly transporting in the direction of the arrow. Laminate while applying pressure with heating. In addition, since there is no dent in the surface of the 2nd insulating material 70 which peeled the cover film 74, it is not necessary to use a vacuum laminator at this time, and it laminates using a normal laminator.

  Lamination of the second insulating material 70 and the second wiring forming copper foil 71 may be performed by a press method in which a laminated roller 72 is used or a heated flat plate is used. A thermoplastic resin may be used for the second insulating material 70 used at this time.

  Then, after a photoresist is applied to the surface of the second wiring forming copper foil 71, development is performed after exposure at regular intervals while being conveyed in the length direction. Then, after applying an etching resist to the back surface of the metal substrate 50, etching is performed, and then the photoresist and the etching resist are removed using an alkaline solution or the like, thereby using a well-known process. As shown in FIG. 2, the same second wiring pattern 71a is formed at regular intervals.

  Next, as shown in FIG. 4C, the bonding tool 56, which is sequentially set on the anvil 55 and heated to a predetermined temperature while being conveyed in the length direction, is positioned for each individual second wiring pattern 71a. Together, it descends and presses against each second wiring pattern 71a to apply heat and pressure. Thereby, with the passage of time, the heat of the bonding tool 56 is transmitted through the second wiring pattern 71a to soften the second insulating material 70, and the second wiring pattern 71a is deformed so that the second insulating material 70 can be deformed. It is buried in and connected to the lower wiring pattern 53a.

  Also in this case, as in the previous example, when heat and pressure are applied to each second wiring pattern 71a using the bonding tool 56, ultrasonic vibrations may be applied simultaneously. The pattern 71a and the lower wiring pattern 53a can be metal-welded to make highly reliable connection both electrically and mechanically.

  And after connecting each 2nd wiring pattern 71a and the lower wiring pattern 53a as mentioned above, when using a thermosetting resin as the 2nd insulating material 70, the whole is heated and 2nd insulating material is used. The curing reaction of 70 is advanced to complete curing. When a thermoplastic resin is used, the entire heating is not performed.

  By the way, when the purpose of connection between the second wiring pattern 71a and the lower wiring pattern 53a is that electrical conduction is not required and only thermal conduction is required, the bonding tool 56 is ultrasonically vibrated. Only apply heat and pressure. At this time, after the second wiring pattern 71a and the lower wiring pattern 53a are connected and then the bonding tool 56 is released, the temperature of the second insulating material 70 around the connecting portion decreases, and the second insulating material around the connecting portion is reduced. 70 is cured and shrinks according to its coefficient of linear expansion. As a result, a force that constantly presses the second wiring pattern 71a and the lower wiring pattern 53a acts on the connecting portion.

  Next, in the same manner as in the previous example, in order to improve the electrical connection with the semiconductor chip and enhance the rust prevention effect, the second wiring pattern 71a and the back surface of the metal substrate 50 are plated with tin or gold. Then, metal plating such as gold plating and indium plating of nickel base is performed. Further, before and after the metal plating, in order to protect the wiring pattern 53a as required, the second wiring pattern 71a is removed except for the chip connection terminal 71b and other connection terminal portions as shown in FIG. The two-layer flexible printed wiring board 76 is formed by providing a solder resist 57 having excellent flexibility by printing.

  7A to 7C show a manufacturing process for forming the two-layer flexible printed circuit board 60 according to the present invention using the two-layer flexible printed wiring board 76 formed by the manufacturing process of FIG.

  As shown in FIG. 7A, a two-layer flexible printed wiring board 76 is provided so as to be transportable in the length direction, and is sequentially set on a heating stage 61 set to a predetermined temperature and bonded to a predetermined temperature. The semiconductor chip 63 is held by the tool 62, and the metal bumps 64 formed by gold plating on the semiconductor chip 63 are lowered in alignment with the chip connection terminals 71b of the second wiring pattern 71a. Pressure is applied together with heat to connect the metal bumps 64 and the chip connection terminals 71b by Au—Sn eutectic bonding.

  In the case where a thermoplastic resin is used for the second insulating material 70, if the time for applying pressure together with the heat through the semiconductor chip 63 is lengthened, the second insulating material 70 is softened by the transmitted heat and the chip connection terminal Since 71b will be buried in the second insulating material 70, the bonding tool 62 is adjusted to rise when it is slightly buried.

  Then, as shown in FIG. 7B, the sealing resin 66 is applied so as to draw the periphery along the side surface of the semiconductor chip 63 using the application nozzle 65, and is injected by capillary action to be second insulating material. It fills between 70 and the semiconductor chip 63. Then, as shown in (C), the sealing resin 66 is thermoset to seal the semiconductor chip 63 with resin, and the two-layer flexible printed circuit board 77 is completed.

  And, when used, a semiconductor module is formed by punching into a predetermined shape for each unit including each semiconductor chip 63 from the long two-layer flexible flexible printed circuit board 77 on which the semiconductor chips 63 are mounted at regular intervals. The semiconductor module is bent with the side on which the semiconductor chip 63 is mounted as the inside, for example, another partial connection terminal of the second wiring pattern 71a is connected to the liquid crystal panel, and another other connection terminal is connected to another printed wiring board. Connecting.

  With such a two-layer flexible printed circuit board 77, the heat generated by the semiconductor chip 63 is guided from the metal bump 64 to the first-layer wiring pattern 53a via the second wiring pattern 71a. Since the ground wiring portion is connected to the metal substrate 50 to which the ground wiring portion is connected via the wiring pattern 53a, the heat of the semiconductor chip 63 to be mounted is transferred to the metal bump 64, the second wiring pattern 71a, and the first layer of the high thermal conductivity. It can be efficiently transmitted by the wiring pattern 53a, and can effectively diverge from the wide metal substrate 50 having a good thermal conductivity to the surrounding space. As a result, it is possible to eliminate the possibility that the operation speed of the semiconductor chip 63 is lowered or the reliability of the semiconductor chip 63 is lowered.

  Moreover, since the ground wiring portion of the second wiring pattern 71a can be electrically connected to the lower wiring pattern 53a and can be electrically connected to the metal substrate 50 via the lower wiring pattern 53a, Similarly, it is excellent in electromagnetic wave shielding properties, reduces electromagnetic noise generated from the wiring pattern 53a, and makes it less susceptible to external electromagnetic noise.

  In addition, as in the previous example, this is also rich in flexibility, and when the semiconductor module is bent and assembled, the metal base member 50 is plastically deformed to reduce the elastic force to return to its original shape, and in recent years it is particularly compact. As a result, it is often bent and assembled in the housing, and the assembling workability in such a case can be improved. Further, according to this example, since the wiring pattern is made two layers, a more complicated circuit configuration can be obtained.

  In the example shown in FIGS. 4 to 7, after the second wiring pattern 71a is formed on the first wiring pattern 53a via the second insulating material 70, the bonding tool 62 is formed on the second wiring pattern 71a. By pressing and applying heat and pressure to deform the second wiring pattern 71a, it is buried in the second insulating material 70 and connected to the first wiring pattern 53a. Then, when the semiconductor chip 63 is mounted by flip chip connection, the heat generated by the semiconductor chip 63 is guided to the first wiring pattern 53a through the second wiring pattern 71a, and the first wiring pattern 53a is transferred to the first wiring pattern 53a. The two-layer flexible printed circuit board 77 that escapes to the metal substrate 50 to which the ground wiring portion is connected has been described.

  However, after forming the upper wiring pattern on the lower wiring pattern via the upper insulating material, the upper wiring pattern is deformed by applying heat and pressure to the upper wiring pattern. The wiring pattern is provided in multiple layers by being buried in the insulating material and connected to the lower wiring pattern. Then, when the semiconductor chip is mounted by flip chip connection, the heat generated by the semiconductor chip is sequentially guided to the lower layer wiring pattern through the upper layer wiring pattern, and the first layer wiring pattern is formed through the multilayer wiring pattern. It can escape to the metal base material which a ground wiring part connects, and can also be set as a multilayer flexible printed circuit board of three or more layers.

FIG. 8 shows a longitudinal section of a double-sided flexible printed circuit board 80 according to the present invention.
In this example, when the front side wiring pattern 53a is formed on the surface of the metal base material 50 via the front side insulating material 52 through the same manufacturing steps as in FIGS. A back side wiring pattern 83a is also formed on the back side via a back side insulating material 82. Then, by applying heat and pressure to the ground wiring portions of the front and back wiring patterns 53a and 83a using a bonding tool, the ground wiring portions are buried in the front and back insulating materials 52 and 82, respectively. Connect to the front or back surface of the substrate 50.

  Thereafter, the front-side second insulating material 70 is laminated on the front-side wiring pattern 53a, and at the same time, the back-side second insulating material 84 is laminated on the back-side wiring pattern 83a, and further, the front-side second wiring is formed on the front-side second insulating material 70. The copper foil for forming the back side second wiring is laminated on the back side second insulating material 84 simultaneously with laminating the copper foil for use. Then, the front-side and back-side second wiring patterns 71a and 85a are formed one side at a time or simultaneously from the front-side and back-side second wiring forming copper foils through a known process. Then, by applying heat and pressure to the front and back second wiring patterns 71a and 85a using a bonding tool, the second wiring patterns 71a and 85a are placed in the front and back second insulating materials 70 and 84, respectively. It is buried and connected to the front or back surface of the metal substrate 50.

  Next, metal plating is performed, and solder resists 57 and 86 are formed before and after the metal plating as necessary. Then, the semiconductor chip 63 is mounted, the sealing resin 66 is filled and the resin sealing is performed, and the double-sided flexible printed circuit board 80 is completed.

  According to such a double-sided flexible printed circuit board 80, the heat generated by the semiconductor chip 63 is transmitted from the metal bump 64 to the lower surface wiring pattern 53a through the surface second wiring pattern 71a, and is transmitted via the surface wiring pattern 53a. The ground wiring portion escapes to the metal base material 50 to which the ground wiring portion is connected, and the heat released to the metal base material 50 is also transmitted to the back side second wiring pattern 85a via the ground wiring portion of the back side wiring pattern 83a. In addition to the effect, the heat dissipation effect of the semiconductor chip 63 can be further enhanced, and the wiring pattern can be double-sided so that a complicated circuit configuration can be obtained.

  The wiring forming copper foils 53, 71 used in the present invention are deformed by the bonding tool 56 and stretched when the wiring patterns 53a, 71a are formed and connected to the metal substrate 50 or the underlying wiring pattern 53a. In order to prevent disconnection, it is desirable to use a rolled copper foil that is soft and has a high elongation rate, or an electrolytic copper foil having similar properties.

  The bonding tool 56 is made of a metal having heat resistance such as stainless steel. The tip shape differs depending on the system, but when applying pressure, heat, and ultrasonic vibration, it is preferable to provide a groove as shown in FIG. On the other hand, when only heat and pressure are applied, it is preferable to have a flat or smooth hemispherical shape so as not to damage the wiring patterns 53a and 71a. In order to deform the fine wiring patterns 53a and 71a and connect them to the metal substrate 50 and the underlying wiring pattern 53a, it is necessary to make the tip thin. However, for example, as shown in FIGS. 10 (A) to (E), the thickest part except the most advanced part has a heat capacity necessary for ensuring the strength of the entire tool and for stabilizing the temperature. It is also preferable from the viewpoint of ensuring.

(A) thru | or (D) is a manufacturing-process figure of the flexible printed wiring board based on this invention. (A) thru | or (C) is a manufacturing process figure which forms the flexible printed circuit board by this invention using the flexible printed wiring board formed by the manufacturing process of FIG. It is a use state figure of the flexible printed circuit board formed by the manufacturing process of FIG. (A) thru | or (D) is a manufacturing-process figure of the two-layer flexible printed wiring board based on this invention. It is a figure which shows an example of the lamination process of the 2nd insulating material and the copper foil for 2nd wiring formation for forming the wiring pattern of the 2nd layer. (A) And (B) is a figure which shows the other example of a lamination process. (A) thru | or (C) is a manufacturing process figure which forms the 2 layer flexible printed circuit board by this invention using the 2 layer flexible printed wiring board formed by the manufacturing process of FIG. 1 is a longitudinal sectional view of a double-sided flexible printed circuit board according to the present invention. It is the front view of an example of the bonding tool used with the manufacturing method concerning this invention, and the bottom view showing the tip. (A) thru | or (E) are the front views of the other example of the bonding tool used with the manufacturing method which concerns on this invention, respectively, and the bottom view which shows the front-end | tip. (A) is a longitudinal cross-sectional view of the conventional flexible printed circuit board, (B) is the use state figure. (A) thru | or (E) is a manufacturing-process figure of another conventional flexible printed wiring board. (A) thru | or (C) is a manufacturing process figure which forms a flexible printed circuit board using the flexible printed wiring board formed by the conventional manufacturing process of FIG. It is a use state figure of the flexible printed circuit board formed by the manufacturing process of FIG. (A) thru | or (F) is a manufacturing-process figure of another conventional flexible printed wiring board. (A) And (B) is a manufacturing-process figure of another conventional flexible printed wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 50 Metal base material 52 (Front side) Insulation material 53a (Front side) Wiring pattern 56 Bonding tool 58 Flexible printed wiring board 60 Flexible printed circuit board 62 Bonding tool 63 Semiconductor chip 64 Metal bump 70 2nd insulating material 71a 2nd wiring pattern 76 Flexible Printed wiring board 77 Flexible printed circuit board 80 Flexible printed circuit board 82 Back side insulating material 83a Back side wiring pattern

Claims (8)

After forming the wiring pattern on the metal substrate via the insulating material,
By applying heat and pressure to the ground wiring portion of the wiring pattern, the ground wiring portion is buried in the insulating material and connected to the metal substrate.
A method for producing a flexible printed wiring board, comprising:   2. The method of manufacturing a flexible printed wiring board according to claim 1, wherein ultrasonic vibration is applied to the ground wiring portion while applying heat and pressure. After forming a second wiring pattern on the wiring pattern via a second insulating material,
By applying heat and pressure to the second wiring pattern, the second wiring pattern is buried in the second insulating material and connected to the wiring pattern.
The manufacturing method of the flexible printed wiring board of Claim 1 or 2 characterized by the above-mentioned. After forming the upper layer wiring pattern via the upper layer insulating material on the lower layer wiring pattern,
By applying heat and pressure to the upper layer wiring pattern, the upper layer wiring pattern is buried in the upper layer insulating material and connected to the lower layer wiring pattern to provide a multilayer wiring pattern,
The manufacturing method of the flexible printed wiring board of Claim 3 characterized by the above-mentioned. After forming the front side wiring pattern via the front side insulating material on the surface of the metal substrate, after forming the back side wiring pattern via the back side insulating material on the back side,
By applying heat and pressure to the ground wiring portions of the front-side and back-side wiring patterns, the ground wiring portions are respectively buried in the front-side or back-side insulating material and connected to the front or back surface of the metal substrate. ,
The manufacturing method of the flexible printed wiring board of any one of Claim 1 thru | or 4 characterized by the above-mentioned.   It forms with the manufacturing method of any one of Claim 1 thru | or 5, The flexible printed wiring board characterized by the above-mentioned.   A method for manufacturing a flexible printed circuit board, comprising mounting a semiconductor chip on the flexible printed wiring board according to claim 6. It forms with the manufacturing method of Claim 7, The flexible printed circuit board characterized by the above-mentioned.

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