KR20210135025A - Adhesive transfer film and method for manufacturing power module substrate using the same - Google Patents

Abstract

The present invention relates to an adhesive transfer film and a method of manufacturing a substrate for a power module using the same. The method includes: a preparation step of preparing an adhesive transfer film to form a pattern-shaped adhesive layer; a temporarily joining step of transferring the adhesive layer on the adhesive transfer film, onto a target object, and then, temporarily joining the target object, on which the adhesive layer is transferred, to a lower substrate through the adhesive layer; and a main joining step of joining an upper substrate to an upper part of the target object, which is temporarily joined on the lower substrate, and sintering the same to mainly join the target object between the lower substrate and the upper substrate. According to the present invention, a patterned adhesive layer is used to temporarily join a plurality of target objects such as a semiconductor chip to a substrate through one single transfer, and, accordingly, there can be advantages of reducing the consumption of adhesive transfer films and considerably reducing time for a temporary joining process.

Description

Adhesive transfer film and substrate manufacturing method for power module using the same

The present invention relates to an adhesive transfer film and a method for manufacturing a substrate for a power module using the same, and to an adhesive transfer film manufactured for bonding semiconductor chips and spacers to a substrate and a method for manufacturing a substrate for a power module using the same.

The power module changes the voltage used in electric vehicles from direct current to alternating current and supplies it to the motor. Due to the high performance of electric vehicles, semiconductor chips mounted on power modules are changing from silicon (Si) to silicon carbide (SiC) with excellent performance. However, heat dissipation is important because power modules using silicon carbide semiconductors generate high heat due to high voltage.

The power module uses a bonding method using Ag sintering paste to mount a semiconductor chip between two substrates and to improve the heat dissipation characteristics of the semiconductor chip. However, in bonding using Ag sintering paste, it is difficult to uniformly apply Ag sintering paste to semiconductor chips or spacers. There is a problem that requires

In addition, the power module uses a soldering bonding method to prevent damage to the semiconductor chip when bonding each component, but the soldering bonding has a problem in that the bonding is separated due to low bonding strength.

An object of the present invention is to simplify the bonding process by manufacturing an adhesive layer made of Ag sintering paste on a film in a pattern form in the bonding process for bonding a semiconductor chip and a spacer to a substrate, and To provide an adhesive transfer film capable of reducing the frequency of occurrence of burrs and lowering the unit cost, and a method for manufacturing a substrate for a power module using the same.

According to a feature of the present invention for achieving the above object, the present invention includes a base film, an adhesive layer formed on the base film, and an adhesive layer formed in a pattern shape on the adhesive layer.

The adhesive layer is an Ag adhesive layer, and the Ag adhesive layer includes 97 to 99 wt% of Ag powder and 1 to 3 wt% of a binder.

The base film is a PET film, and the adhesive layer is OCA.

The method for manufacturing a substrate for a power module includes a preparation step of preparing an adhesive transfer film so that an adhesive layer having a pattern shape corresponding to the position of the object is formed, and an adhesive layer on the adhesive transfer film is transferred to the object, and the object to which the adhesive layer is transferred is transferred to the adhesive layer. It includes a temporary bonding step of temporarily bonding to the lower substrate with a furnace and a bonding step of bonding the upper substrate to the upper portion of the object temporarily bonded on the lower substrate and sintering to bond the object between the lower substrate and the upper substrate.

The preparation step includes attaching the OCA film on the PET film, mesh screen printing or stencil printing of the Ag sintering paste on the OCA film, and drying the Ag sintering paste to form a patterned Ag adhesive layer.

The temporary bonding step includes fixing the adhesive transfer film to a die, fixing the object to the upper chuck for adsorbing and fixing the object using vacuum, and heating the upper chuck and the die while heating the object fixed to the upper chuck to the adhesive transfer film Transferring the adhesive layer on the adhesive transfer film to the object by pressing to the side, raising the upper chuck while maintaining a vacuum to raise the object to which the adhesive layer is attached, transferring the upper chuck to the upper part of the lower substrate, and the upper chuck It includes the steps of temporarily bonding the object to the lower substrate by pressing the object fixed to the lower substrate side, releasing the vacuum and raising the upper chuck.

The die is heated to a temperature of 80-100°C, and the upper chuck is heated to a temperature of 100-170°C.

Sintering is carried out for 2 to 5 minutes while heating and pressing at 240 ~ 300 ℃.

In the temporary bonding step, the object includes a semiconductor chip, a first conductive spacer and a second conductive spacer, and the temporary bonding step is to transfer the adhesive layer on the adhesive transfer film to the lower surface of the semiconductor chip, and the semiconductor chip to which the adhesive layer is transferred is applied to the adhesive layer. A first temporary bonding step of temporary bonding to the upper surface of the lower substrate via a medium, and transferring the adhesive layer on the adhesive transfer film to the lower surfaces of the first conductive spacer and the second conductive spacer, the first conductive spacer and the second adhesive layer transferred thereto and a second temporary bonding step of temporarily bonding a conductive spacer to the upper surface of the semiconductor chip and the upper surface of the lower substrate via the adhesive layer.

The height of the second conductive spacer is the same as the sum of the heights of the semiconductor chip, the adhesive layer, and the first conductive spacer.

The bonding step includes forming an adhesive layer on the lower surface of the upper substrate so as to correspond to the first conductive spacer and the second conductive spacer temporarily bonded on the lower substrate, fixing the upper substrate to the upper chuck, and fixing the upper substrate to the upper chuck. and main bonding the semiconductor chip and the first conductive spacer and the second conductive spacer between the upper substrate and the lower substrate by heating and pressing the substrate toward the lower substrate.

The upper substrate and the lower substrate may be an AMB substrate or a DBC substrate.

The present invention prepares an adhesive transfer film in which an adhesive layer is formed in a pattern form on a film, and the patterned adhesive layer is used for bonding a semiconductor chip and a spacer to a lower substrate. In addition, according to the present invention, an adhesive layer is formed on the final upper substrate by a printing method, and is sintered by heating and pressing while bonding with the spacer of the lower substrate.

Therefore, the present invention can be mass-produced by patterning the adhesive layer, and a plurality of objects, such as semiconductor chips, can be temporarily bonded to the substrate with one transfer.

In addition, according to the present invention, since the patterned adhesive layer is transferred in one-to-one correspondence with the object, the generation of burrs during transfer can be greatly reduced, and the area of the adhesive layer using Ag in the adhesive transfer film is greatly reduced, thereby reducing the product cost. It has the effect of significantly lowering it.

In addition, in the present invention, since the main bonding of the spacer on the lower substrate and the upper substrate is possible without turning over the lower substrate, sintering is simplified once, thereby reducing the process time and reducing the equipment investment cost.

In addition, in the present invention, the base film holds the flatness of the lower surface of the adhesive layer bonding the semiconductor chip and the spacer between the lower substrate and the upper substrate, and the upper surface flatness of the adhesive layer can be obtained by the pressing force of the upper chuck, so the thickness of the adhesive layer is reduced. It can be formed thinly and uniformly. Therefore, the present invention enables uniform bonding of the upper substrate and the lower substrate, which has an effect that can contribute to increasing the reliability of the power module product.

1 is a cross-sectional view showing an adhesive transfer film according to an embodiment of the present invention.
2 is a view for explaining a method of manufacturing a substrate for a power module according to an embodiment of the present invention.
3 is a plan view showing an example of a substrate for a power module according to an embodiment of the present invention.
FIG. 4 is a view for explaining a method of manufacturing a substrate for a power module of FIG. 3;
5 is a bottom view of an upper chuck to which a semiconductor chip is fixed, and a plan view of an adhesive transfer film corresponding thereto, as an application example of the present invention.
Fig. 6 is a cross-sectional view of Fig. 5;
7 is a view for explaining a method of manufacturing a substrate for a power module according to an application example of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention includes an adhesive transfer film 10 for bonding an object such as a semiconductor chip, a conductive spacer (CQC), or an insulating spacer to a substrate.

As shown in FIG. 1 , the adhesive transfer film 10 is a base film 11 , a sticky layer 12 formed on the base film 11 , and a pattern formed on the adhesive layer 12 . and an adhesive layer 13 .

The adhesive transfer film 10 is prepared by forming an Ag sintering paste on a film in the form of a pattern. The base film 11 is a PET film, the adhesive layer 12 is an OCA film, and the adhesive layer 13 is an Ag adhesive layer. The Ag adhesive layer 13 is used for good heat dissipation properties.

The Ag adhesive layer includes 98 to 99% by weight of Ag powder and 1 to 2% by weight of a binder. The Ag adhesive layer increases the content of Ag powder to increase thermal conductivity.

Ag has good heat dissipation properties due to its high thermal conductivity, and allows the adhesive layer to have conductivity. The binder ensures that Ag has high adhesion and is uniformly applied. The Ag adhesive layer enables low-temperature sintering by maximizing the content of Ag powder and minimizing the content of the binder in the range that can be applied uniformly. The low temperature sintering temperature may be in the range of 240 ~ 300 ℃.

When the content of the binder is lowered to 1 to 2 wt%, the organic content is lowered, so that the thermal decomposition and sintering temperature of the Ag adhesive layer can be lowered by about 60 to 100°C. The low sintering temperature enables fast sintering of the Ag adhesive layer. The rapid sintering of the Ag adhesive layer reduces the shrinkage during sintering and prevents cracking of the sintered layer, thereby lowering the defect rate.

The Ag adhesive layer contains Ag powder in the form of nanoparticles. Ag powder has a liquid phase temperature of 900° C. or higher, so it can be sintered in a range of 240 to 300° C., and Ag solder cannot be sintered in a range of 240 to 300° C. because a liquid phase temperature is 200° C. or higher.

The Ag adhesive layer has high thermal conductivity with a thermal conductivity of 200 to 300 W/mK, a shear strength of 50 MPa or more, and a viscosity of 40 to 100 kcps, so it has high adhesion to various surfaces. It is also possible to use Au instead of Ag, but it is preferable to use Ag in view of cost.

The adhesive transfer film 10 may be formed by attaching an OCA film on the base film 11 , printing Ag sintering paste on the OCA film in a pattern form, and drying. Alternatively, the adhesive transfer film 10 may be formed by printing Ag sintering paste in a pattern form on the base film 11 and drying it. In the method of printing the adhesive layer 13 in the form of a pattern, mesh screen printing or stencil printing may be applied to uniformly control the height of the adhesive layer 13 . In stencil printing, a stencil metal mask having a pattern-shaped hole is disposed on the upper surface of the base film 11 and screen-printed to form an adhesive layer pattern of a certain thickness. Mesh screen printing is a printing method in which an adhesive layer pattern is transferred onto a base film using a screen mesh. A mesh screen is chemically treated (coated) of a certain area of a finely woven fabric to form a film on the mesh to prevent the paste from passing through, and a screen mesh is made and used so that the paste is transmitted through the development process of only the desired image area.

The adhesive layer 12 improves the releasability of the adhesive layer 13 to the base film 11 . The Ag sintering paste contains 97 to 99% by weight of Ag powder and 1 to 3% by weight of the binder in the same manner as the Ag adhesive layer.

The adhesive transfer film 10 manufactured in the form of a film can make the height of the adhesive layer 13 very uniform. When bonding an object between two substrates, the height of the adhesive layer 13 must be uniform so that a tolerance does not occur between the two substrates and a problem does not occur in the final product.

In addition, when the adhesive transfer film 10 is used when bonding an object between two substrates, void and stand-off defects are eliminated compared to the paste process of applying a paste to a conventional object and bonding to a substrate. can be reduced A void refers to the occurrence of pores in the adhesive layer 13 after sintering, and a stand-off defect means that the object is inclined to one side without being flatly bonded to the substrate.

In the adhesive transfer film 10 , the thickness of the base film 11 may be 75 to 100 μm. The thickness of the adhesive layer 13 may be 40 to 60 μm, preferably 50 μm. The adhesive transfer film 10 can control the thickness and voids of the adhesive layer 13 .

The adhesive transfer film 10 may be applied to a method of manufacturing a substrate for a power module.

2 shows a method of manufacturing a substrate for a power module using an adhesive transfer film.

As shown in FIG. 2 , in the method of manufacturing a substrate for a power module, an adhesive layer 13 is transferred to an object 40 using an adhesive transfer film 10 , and the object 40 to which the adhesive layer 13 is transferred is lowered. It may be temporarily bonded to the upper surface of the substrate 20 . The adhesive layer 13 is formed on the base film 11 in a pattern shape corresponding to a position corresponding to the object 40 . The adhesive layer 13 may be formed on the entire surface of the base film 11, but in this case, the amount of consumption of the adhesive transfer film 10 increases and the transfer may not be performed cleanly. It may be the cause of assembly failure. Therefore, forming the adhesive layer 13 on the base film 11 in a pattern shape corresponding to the position corresponding to the object 40 can reduce the amount of the adhesive transfer film 10 used, and also the defect factors caused by burrs. can be reduced

A method of manufacturing a substrate for a power module includes a preparation step of preparing an adhesive transfer film 10, a temporary bonding step of transferring an adhesive layer on the adhesive transfer film to an object, and temporarily bonding the object to which the adhesive layer is transferred to a lower substrate through the adhesive layer And, a main bonding step of temporarily bonding and sintering the upper substrate 30 to the upper portion of the object 40 temporarily bonded on the lower substrate 20 to bond the object 40 between the lower substrate and the upper substrate 30 . includes

The preparation step is a step of pre-coating an adhesive layer on the base film in a pattern shape corresponding to a position corresponding to the object.

The preparation step includes preparing the base film 11, forming the adhesive layer 12 on the base film 11, and patterning the adhesive layer 12 by stencil printing or mesh screen printing method. and forming an adhesive layer 13 of For example, the preparation step includes attaching an OCA film on a PET film, applying or printing Ag sintering paste on the OCA film, and drying the Ag adhesive layer to form an Ag adhesive layer. The base film 11 may be a PC (Polycarbonate) film in addition to a PET (Polyester) film. However, compared to the PC film, the PET film is advantageous in maintaining the flatness of the lower surface of the adhesive layer 13 . The flatness of the upper surface of the adhesive layer 13 may be maintained by the pressing force of the upper chuck 3 . If the flatness of the adhesive layer 13 is not good, there is a problem in that the adhesive layer is bent during sintering.

As shown in FIG. 2 , in the temporary welding step, the adhesive transfer film 10 is fixed to the die 1 , and the object 40 is attached to the upper chuck 3 for adsorbing and fixing the object 40 using a vacuum. In the fixing step (s1), while heating the upper chuck 3 and the die 1, respectively, pressing the object 40 fixed to the upper chuck 3 toward the adhesive transfer film 10 side to the adhesive transfer film 10 The step (s2) of transferring the adhesive layer 13 on the upper surface to the object 40, and the step of raising the upper chuck 3 while maintaining the vacuum to raise the object 40 to which the adhesive layer 13 is attached (s3) and , a step (s4) of transferring the upper chuck 3 to the upper portion of the lower substrate 20, and pressing the object 40 fixed to the upper chuck 3 toward the lower substrate 20 to lower the object 40 It includes a step (s5) of temporarily bonding the substrate 20, and a step (s6) of releasing the vacuum of the upper chuck 3 and raising the upper chuck 3 . Steps (s1) to (s3) are steps of transferring the adhesive layer 13 from the adhesive transfer film 10 to the object 40, and steps (s5) to (s6) are the steps to which the adhesive layer 13 is transferred. ) is a step of temporary bonding to the lower substrate 20 .

Step (s1) is a step in which the upper chuck 3 picks up the object 40 in a vacuum.

Step (s2) is a step of transferring the adhesive layer 13 to the lower surface of the object 40. In step (s2), the die 1 is heated to a temperature of 80 ~ 100 ℃, the upper chuck 3 is heated to a temperature of 100 ~ 170 ℃. Preferably, the die is heated to a temperature of 80 to 100°C, and the upper chuck 3 is heated to a temperature of 160°C. Pressurization may be performed at 1-4 MPa. When the heating temperature of the upper chuck 3 is higher than the heating temperature of the die 1 , the adhesive layer 13 can be strongly adhered to the object 40 having a higher temperature.

Step (s3) is a step of picking up the adhesive layer 13 by attaching it to the object 40 . In step (s3), the adhesive layer 13 is attached to the lower surface of the object 40 by transfer and is separated from the base film 11 . At this time, since the adhesive layer 12 is not separated from the base film 11 , the adhesive layer 13 can be separated cleanly.

Step (s4) is a step of transferring the object 40 to the upper portion of the lower substrate 20 in order to temporarily bond the object 40 on the lower substrate 20 . The lower substrate 20 may be an AMB substrate or a DBC substrate.

Step (s5) is a step of temporarily bonding the object 40 on the lower substrate 20 by pressing the object 40 fixed to the upper chuck 3 toward the lower substrate 20 . In step (s5), the die 1 is heated to a temperature of 80 ~ 100 ℃, the upper chuck 3 is heated to a temperature of 100 ~ 170 ℃. Preferably, the die 1 is heated to a temperature of 80 to 100°C, and the upper chuck 3 is heated to a temperature of 160°C. Pressurization may be performed in the range of 1 to 4 MPa.

Step (s6) is a step of releasing the vacuum and raising the upper chuck 3 to complete the temporary welding. In this way, the adhesive transfer film 10 is heated using the die 1 heated to a temperature of 80 to 100° C., and the object 40 is heated using the upper chuck 3 heated to a temperature of 100 to 170° C. After heating, when the upper chuck 3 is lowered so that the object 40 is pressed toward the adhesive transfer film 10, the adhesive layer 13 on the adhesive transfer film 10 is on the lower surface of the object 40 with a higher temperature. can be transcribed.

After the temporary bonding step, the upper substrate (refer to reference numeral 30 in FIG. 4 ) is bonded to the upper portion of the object 40 temporarily bonded on the lower substrate 20 and sintered between the lower substrate 20 and the upper substrate 30 . A step of bonding the object 40 is performed. Sintering is carried out for 2 to 5 minutes while heating and pressing at 240 ~ 300 ℃. Pressurization may be performed in the range of 8 to 15 MPa.

The pressurization is to prevent the occurrence of voids. Pressurization increases the density and significantly reduces the sintering process time. Therefore, when the pressure sintering is performed, the adhesive layer 13 is dense without holes, so that the heat conduction is increased and the heat dissipation characteristics are excellent.

The sintering temperature and time at the time of main bonding can be adjusted within the above-mentioned range in order to shorten the mass production time. For example, for sintering during main bonding, it is preferable to pressurize at 250°C for 5 minutes, but pressurization may be performed at 300°C for 2 minutes to improve mass productivity. Sintering is intended to improve bonding strength. In addition, the flatness of the adhesive layer 13 is ensured by pressing with a uniform pressure when pressing.

3 shows an example of a substrate for a power module.

The power module has a multilayer structure of a lower substrate 20 and an upper substrate 30 , and a semiconductor chip 40a is installed between the lower substrate 20 and the upper substrate (reference numeral 30 in FIG. 4 ). The semiconductor chip is a power semiconductor chip such as Si, SiC, or GaN.

The lower substrate 20 and the upper substrate 30 are a metal layer 22 brazed to at least one surface of the ceramic substrate 21 and the ceramic substrate 21 to increase heat dissipation efficiency of the heat generated from the semiconductor chip 40a. A ceramic substrate comprising a. The ceramic substrate 21 may be, for example, any one of _{alumina (Al 2} O ₃ ), AlN, SiN, and Si ₃ N _{4 .} The metal layer 22 is formed of an electrode pattern for mounting the semiconductor chip 40a and an electrode pattern for mounting a driving element, respectively, with a metal foil brazed on the ceramic substrate 21 . The metal foil may be an aluminum foil or a copper foil as an example. As an example, the metal foil is fired at 780° C. to 1100° C. on a ceramic substrate and brazed to the ceramic substrate. The embodiment is described using an AMB substrate or a DBC substrate as an example, but a TPC substrate or a DBA substrate may be applied. However, in terms of durability and heat dissipation efficiency, AMB substrates are most suitable.

The semiconductor chip 40a, the first conductive spacer 40b, and the second conductive spacer 40c transfer the adhesive layer 13 on the adhesive transfer film 10, and use the adhesive layer 13 to the lower substrate 20 and the upper substrate 30 . The adhesive layer 13 is an Ag adhesive layer having high heat dissipation.

When using a substrate having a top and bottom multilayer structure, an insulating spacer is used to maintain a gap between the lower substrate 20 and the upper substrate 30, and when electricity needs to pass between the lower substrate 20 and the upper substrate 30 Conductive spacers 40b and 40c are used to ensure heat dissipation and conductivity. In this case, the Ag adhesive layer having high heat dissipation is used to prevent heat generated in the semiconductor chip 40a from being diffused to the upper substrate 30 through the lower substrate 20 .

In FIG. 3 , one positioned at the center of the lower substrate 20 is the second conductive spacer 40c, and four spaced apart from both sides of the second conductive spacer 40c are bonded to the upper surface of the semiconductor chip 40a. and a first conductive spacer 40b bonded to the upper substrate 30 . In the method of manufacturing a substrate for a power module of the present invention, a semiconductor chip 40a and a first conductive spacer 40b are laminatedly bonded between the lower substrate 20 and the upper substrate 30 . In addition, the second conductive spacer 40c is bonded between the lower substrate 20 and the upper substrate 30 at the same height as the sum of the heights of the semiconductor chip 40a and the first conductive spacer to provide heat dissipation characteristics and electrical conductivity. can be obtained

FIG. 4 shows an embodiment of a method of manufacturing a substrate for a power module, including temporarily bonding a semiconductor chip, a first conductive spacer, and a second conductive spacer to the lower substrate of FIG. 3 , and bonding and sintering an upper substrate thereon. has been

As shown in FIG. 4, in the method for manufacturing a substrate for a power module, the adhesive layer 13 on the adhesive transfer film 10 is transferred to the lower surface of the semiconductor chip 40a, and the adhesive layer 13 is transferred to the semiconductor chip 40a. A first temporary bonding step (s10) of temporarily bonding to the upper surface of the lower substrate 20 via the adhesive layer 13, and the adhesive layer 13 on the adhesive transfer film 10 with the lower surface of the first conductive spacer 40b The semiconductor chip 40a is transferred to the lower surface of the second conductive spacer 40c, respectively, and the first conductive spacer 40b and the second conductive spacer 40c to which the adhesive layer 13 is transferred are interposed through the adhesive layer 13. A second temporary bonding step (s20) of temporarily bonding the upper surface and the upper surface of the lower substrate 20 is included.

In the first temporary bonding step s10 , the semiconductor chip 40a is a power semiconductor chip such as Si, SiC, or GaN. In the first temporary bonding step (s10), the adhesive layer 13 is formed on the base film 11 in a shape corresponding to the position corresponding to the semiconductor chip 40a, so that clean transfer without burr is possible. .

In the second bonding step s20 , the first conductive spacer 40b and the second conductive spacer 40c are interconnection spacers (CQC). The interconnection spacer CQC is used when electricity needs to pass between the lower substrate 20 and the upper substrate 30 . The interconnection spacer (CQC) may be formed in the form of a conductive metal block or in the form of a block in which a conductive metal is coated on the outer surface of the injection-molded product. The height of the second conductive spacer 40c is the same as the sum of the heights of the semiconductor chip 40a, the adhesive layer 13, and the first conductive spacer 40b.

The lower substrate 20 may be an AMB substrate or a DBC substrate. In the first temporary bonding step (s10) and the second temporary bonding step (s20), the upper chuck 3 is vacuum-adsorbed to the upper chuck 3 by a semiconductor chip 40a, a first conductive spacer 40b, and a second conductive spacer ( 40c) fix the back.

In the first temporary welding step (s10) and the second temporary welding step (s20), the heating and pressurization by the upper chuck 3 is performed at a temperature of 100 to 170° C. and a pressure of 1 to 4 MPa for about 20 seconds. At this time, the die 1 is heated and maintained at a temperature of 80 to 100 °C.

After the second temporary bonding step (s20), the upper substrate 30 is temporarily bonded to the upper portions of the first conductive spacer 40b and the second conductive spacer 40c temporarily bonded on the lower substrate 20 and sintered, thereby forming the lower substrate. A bonding step of bonding the semiconductor chip 40a, the first conductive spacer 40b, and the second conductive spacer 40c between the 20 and the upper substrate 30 is performed.

The bonding step is a step of forming the adhesive layer 13 on the lower surface of the upper substrate 30 to correspond to the first conductive spacer 40b and the second conductive spacer 40c temporarily bonded on the lower substrate 20 (s30). ), the upper substrate 30 is fixed to the upper chuck 3 , and the upper substrate 30 fixed to the upper chuck 3 is heated and pressed toward the lower substrate 20 to form the semiconductor chip 40a and the first conductivity and main bonding ( s40 ) of the temporary bonding body 40 ′ of the spacer 40b and the second conductive spacer 40c between the upper substrate 30 and the lower substrate 20 . In the bonding step, heating and pressurization is performed for 2 minutes to 5 minutes at a temperature of 240 to 300 ℃ and a pressure of 8 to 15 MPa.

The adhesive layer 13 of the temporary bonding step becomes a sintered bonding layer 13' after performing the bonding step. Since the sintered adhesive layer 13' is dense without voids by pressure sintering, bonding strength is improved and it functions as an excellent heat dissipation electrode.

5 shows another example of a method of manufacturing a substrate for a power module.

A method of manufacturing a substrate for a power module can be mass-produced by using a patterned adhesive layer.

5, the plurality of semiconductor chips 40a can be fixed to the upper chuck 3 manufactured in the form of a jig to fix the plurality of semiconductor chips 40a, and the semiconductor chips 40a The adhesive transfer film 10 may be manufactured so that the adhesive layer 13 is formed in a pattern shape corresponding to a position corresponding to the . In this case, since the semiconductor chips 40a can be fixed for each position and the adhesive layer 13 can be transferred to the semiconductor chips 40a at a time through a one-time heating and pressing process, the temporary bonding process time can be significantly reduced.

As shown in FIG. 6 , the upper chuck 3 is provided with a vacuum suction line S so that the semiconductor chip 40a can be fixed at a set position by vacuum suction. In the adhesive transfer film 10 , the adhesive layer 13 is formed in a pattern shape corresponding to a position corresponding to the semiconductor chip 40a. The adhesive layer 13 is pre-printed on the base film 11 and dried.

As shown in FIG. 7 , in the method for manufacturing a substrate for a power module capable of mass production, the adhesive transfer film 10 on which the patterned adhesive layer 13 is formed is fixed on the die 1 , and the vacuum adsorption line S is formed. The semiconductor chips 40a are fixed to the upper chuck 3 by using. Next, the upper chuck 3 is heated with a heat and pressure press 5 and the semiconductor chips 40a fixed to the upper chuck 3 are pressed toward the adhesive transfer film 10 while heating the die 1 with a heater to obtain an adhesive. The adhesive layers 13 on the transfer film 10 are transferred to the semiconductor chips 40a. Next, the upper chuck 3 is raised while maintaining the vacuum to raise the semiconductor chips 40a to which the adhesive layer 13 is attached.

The die 1 is heated to a temperature of 80 to 100° C. using an internal heater, and the upper chuck 3 is heated to a temperature of 100 to 170° C. by using a heating and pressurizing press 5 . Preferably, the die is heated to a temperature of 80 to 100 °C, and the heating press 5 is heated to a temperature of 160 °C. Pressurization may be performed at 1-4 MPa. When the heating temperature of the heating and pressing press 5 is higher than the heating temperature of the die 1 , the adhesive layers 13 can be strongly adhered to the semiconductor chips 40a having a higher temperature.

Referring to FIG. 7 , the tip of the adhesive layer 13 attached to the semiconductor chip 40a is contracted due to the temperature of the transfer process, and since the patterned adhesive layer 13 is transferred to the semiconductor chip 40a, the The burr factor can be significantly reduced.

If the adhesive layer 13 is formed on the entire surface of the base film 11 and the adhesive layer 13 is transferred to the semiconductor chip, the adhesive layer 13 transferred to the semiconductor chip 40a while the upper chuck 3 is raised. ) may be torn off and a burr may be generated.

In the method for manufacturing a substrate for a power module of the present invention, the base film 11 holds the flatness of the lower surface of the adhesive layer 13 , and the flatness of the upper surface of the adhesive layer 13 can be obtained by the pressing force of the upper chuck 3 . Therefore, the thickness of the adhesive layer 13 can be formed thin and uniform.

In addition, in the above-described method for manufacturing a substrate for a power module of the present invention, the semiconductor chip 40a and the first conductive spacer 40b are laminated on the lower substrate 20 using the adhesive transfer film 10 manufactured in the form of a film. After bonding, the bonding process is completed in one final sintering furnace, so the process is minimized, the process time can be reduced, and the equipment investment cost is also reduced.

If the operation of temporarily bonding the semiconductor chip 40a to the lower substrate 20 and temporarily bonding the first conductive spacer 40b to the semiconductor chip 40a is performed using Ag sintering paste, the semiconductor chip on the lower substrate The first conductive spacer and the first conductive spacer are provisionally bonded and then primary sintered, and Ag sintering paste is additionally applied on the first conductive spacer 40b to bond the upper substrate 30 to the first conductive spacer 40b, 2 There is a hassle of secondary sintering, and since it is difficult to apply the Ag sintering paste uniformly, it is necessary to pressurize for each sintering process, so the process time is long, and expensive equipment is required for the application of the Ag sintering paste, so the equipment investment cost is increased do. Therefore, it is effective to manufacture Ag sintering paste in the form of a film and apply it to a method for manufacturing a substrate for a power module in terms of reducing process time and equipment investment cost.

Furthermore, the method for manufacturing a substrate for a power module of the present invention described above can be mass-produced by patterning the adhesive layer. That is, an adhesive transfer film having an adhesive layer in which the semiconductor chips are arranged in advance to correspond to positions to be mounted on the power module using an upper chuck manufactured in the form of a jig, and the adhesive layer is patterned so that the adhesive layer is transferred to the position of the semiconductor chip on the upper chuck. is prepared, and then the adhesive layer may be transferred to the lower surfaces of the semiconductor chips by heating and pressing. Since the semiconductor chip can be temporarily bonded to the DBC substrate or AMB substrate with one transfer, it is possible to reduce the amount of adhesive transfer film used and significantly reduce the bonding process time. In addition, since the patterned adhesive layer is attached to the semiconductor chip in a one-to-one correspondence, it is effective in that it can greatly reduce the generation of residues during transfer, and the area of the adhesive layer using Ag is greatly reduced, which can significantly lower the product cost.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is disclosed in the drawings and in the specification with preferred embodiments. Here, although specific terms have been used, they are used only for the purpose of describing the present invention and are not used to limit the meaning or the scope of the present invention described in the claims. Therefore, it will be understood by those skilled in the art that various modifications and equivalent other embodiments of the present invention are possible therefrom. Accordingly, the true technical scope of the present invention should be defined by the technical spirit of the appended claims.

10: adhesive transfer film 11: base film
12: adhesive layer 13: adhesive layer
13': sintered adhesive layer 20: lower substrate
21,31: ceramic substrate 22,32: metal layer
30: upper substrate 40: object
40a: semiconductor chip 40b: first conductive spacer
40c: second conductive spacer 1: die
3: Upper chuck 5: Heating and pressing press

Claims (12)

base film;
an adhesive layer formed on the base film; and
an adhesive layer formed in a pattern shape on the adhesive layer;
Adhesive transfer film comprising a. According to claim 1,
The adhesive layer is an Ag adhesive layer,
The Ag adhesive layer is an adhesive transfer film comprising 97 to 99 wt% of Ag powder and 1 to 3 wt% of a binder. According to claim 1,
The base film is a PET film,
The adhesive layer is an adhesive transfer film of OCA. A preparation step of preparing an adhesive transfer film so that an adhesive layer having a pattern shape corresponding to the position of the object is formed;
a temporary bonding step of transferring the adhesive layer on the adhesive transfer film to an object, and temporarily bonding the object to which the adhesive layer is transferred to a lower substrate through the adhesive layer; and
bonding an upper substrate to an upper portion of the object temporarily bonded on the lower substrate and sintering to bond the object between the lower substrate and the upper substrate;
A method of manufacturing a substrate for a power module comprising a. 5. The method of claim 4,
The preparation step is
attaching the OCA film on the PET film; and
mesh screen printing or stencil printing of Ag sintering paste on the OCA film, and drying to form an Ag adhesive layer having a pattern shape;
A method of manufacturing a substrate for a power module comprising a. 5. The method of claim 4,
The bonding step is
fixing the adhesive transfer film to a die and fixing the object to an upper chuck for adsorbing and fixing the object using a vacuum;
transferring the adhesive layer on the adhesive transfer film to the object by pressing the object fixed to the upper chuck toward the adhesive transfer film while heating the upper chuck and the die, respectively;
raising the object to which the adhesive layer is attached by raising the upper chuck while maintaining a vacuum;
transferring the upper chuck to an upper portion of the lower substrate;
pressing the object fixed to the upper chuck toward the lower substrate to temporarily bond the object to the lower substrate; and
releasing the vacuum and raising the upper chuck;
A method of manufacturing a substrate for a power module comprising a. 7. The method of claim 6,
A method of manufacturing a substrate for a power module, wherein the die is heated to a temperature of 80 to 100°C, and the upper chuck is heated to a temperature of 100 to 170°C. 5. The method of claim 4,
The sintering is a method of manufacturing a substrate for a power module that is performed for 2 minutes to 5 minutes while heating and pressing at 240 to 300 °C. 5. The method of claim 4,
In the bonding step,
The object includes a semiconductor chip, a first conductive spacer and a second conductive spacer,
The bonding step is
a first temporary bonding step of transferring the adhesive layer on the adhesive transfer film to the lower surface of the semiconductor chip, and temporarily bonding the semiconductor chip to which the adhesive layer is transferred to the upper surface of the lower substrate through the adhesive layer; and
The adhesive layer on the adhesive transfer film is transferred to the lower surface of the first conductive spacer and the second conductive spacer, and the first conductive spacer and the second conductive spacer to which the adhesive layer is transferred are transferred to the upper surface of the semiconductor chip through the adhesive layer. a second temporary bonding step of temporarily bonding the upper surface of the lower substrate;
A method of manufacturing a substrate for a power module comprising a. 10. The method of claim 9,
The height of the second conductive spacer is the same height as the sum of the heights of the semiconductor chip, the adhesive layer, and the first conductive spacer. 10. The method of claim 9,
The bonding step is
forming an adhesive layer on a lower surface of the upper substrate to correspond to the first conductive spacer and the second conductive spacer that are temporarily bonded on the lower substrate; and
The upper substrate is fixed to an upper chuck, and the upper substrate fixed to the upper chuck is heated and pressed toward the lower substrate to form a temporary bonding body between the semiconductor chip and the first conductive spacer and the second conductive spacer to the upper substrate and the upper substrate. bonding between the lower substrates;
A method of manufacturing a substrate for a power module comprising a. 5. The method of claim 4,
A method of manufacturing a substrate for a power module using an AMB substrate or a DBC substrate as the upper substrate and the lower substrate.

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