JPH09246324A - Electronic component and bump forming method thereof - Google Patents

Abstract

(57) Abstract: An electronic component having high connection reliability is provided at low cost. SOLUTION: A flat portion is formed on a bump of an electronic component, and the flat portion position is controlled so that the flat portion position is lower than a bump apex position when the bump is heated and melted into a sphere. Even if there is a warp in the bump, the bump connection can be reliably obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is mounted on a circuit board,
For example, a flip chip type electronic component to be connected,
The present invention relates to a method of forming bumps, for example, solder bumps used for connecting electronic components and a circuit board.

[0002]

2. Description of the Related Art As shown in FIG. 2, in the conventional electronic component 1, the bumps 3 on the terminal electrodes 2 are in the state of being heated and melted into spheres during bump formation, that is, the bump surface is a bump spherical portion 10. . A process of mounting and connecting this electronic component on a circuit board is shown in FIG. In FIG. 3A, the flux 7 is attached to the bump spherical portion 10 of the bump 3 of the electronic component 1. After that, as shown in FIG. 3B, the bumps 3 are positioned and mounted so that the bumps 3 and the connection electrodes 6 on the circuit board 5 face each other, and are temporarily fixed by the flux 7. Then, in FIG. 3C, the connection electrode 6 and the terminal electrode 2 are bonded to the bonding bumps 9 by heating in the reflow furnace 106, and as a result, the electronic component 1 and the circuit board 5 are electrically connected. .

As a method for forming bumps, particularly solder bumps, a bump forming method using solder balls is known as disclosed in Japanese Patent Laid-Open No. 5-129374. This is because solder balls are aligned and adsorbed by an adsorption jig having an adsorption hole at a position facing a bump-formed terminal electrode of an electronic component, and the solder ball is transferred to the terminal electrode position via a flack or the like and temporarily fixed. Then, the solder balls are heated and melted in that state to form bumps.

As a conventional bump forming method using solder paste, "Hitachi Techno Engineering Fine Pitch SMT Mounting Technology Seminar Material" Dec / 5-
As shown in p6-6 to p6-11 of 6/1995, a method of transferring a paste onto a terminal electrode by screen mask printing and forming a bump by heating and melting the paste, and the Welding Society of Japan Sponsored 1st Symposium on "Microj
oining and AssemblyTechnology in Electronics "Feb / 9
-10/1995, Tokyo Proceedings P187-192, place a mask on the electronic component, fill the mask with solder paste by printing, heat melt the solder paste with the mask placed, and bump Forming method, and Japanese Patent Laid-Open No. 7-
There is known a method of filling a solder paste in a concave portion of a base material having a concave portion at a position facing a terminal electrode as shown in Japanese Patent No. 245309, mounting an electronic component on the concave portion, and heating and melting.

[0005]

When the electronic component 1 in which the apex of the bump 3 of FIG. 2 is the bump spherical portion 10 is mounted on a circuit board, the bump spherical portion 10 and the connecting electrode 6 are formed as shown in FIG. 3B. Since the contact point with the point contact is a point contact, the bump spherical portion 10 and the connection electrode 6 are displaced due to mechanical vibration during transportation, and the bump is not connected when the electronic component and the circuit board are heated and melt-bonded. There was a problem.

In the case of a warped electronic component or circuit board, as shown in FIG. 3 (c), the electronic component 1 and the circuit board 5 are arranged at a bonding interval 30 after the electronic component 1 and the circuit board 5 are melted by heating. A part in which the bonding interval 30 is larger than that in the case where there is no warp is generated. Therefore, when the minimum value of the bump height of the electronic component 1 is smaller than the maximum value of the bonding interval 30, the unconnected bump 8 is generated.
As a countermeasure for this, a large investment was required for technological development and device development to prevent warpage of electronic components and circuit boards and to improve the accuracy of solder supply and reduce variations in bump height. Also, when designing the terminal electrode diameter and the bump size, there is a problem that the design margin has to be divided due to the warpage, which reduces the degree of freedom in design. The conventional bump forming method has a problem that the manufacturing cost of the solder balls is high. In addition, when the number of bumps is large, or when the solder ball diameter or pitch is small, solder ball alignment and suction errors and transfer errors to electronic circuits occur frequently, and it is necessary to retry suction and transfer. However, there was a problem that the production tact increased and the yield decreased.

Further, in the method of forming the bumps by transferring the solder paste onto the terminal electrodes by screen mask printing and heating and melting the solder paste, when the solder paste is transferred onto the terminal electrodes, the solder is applied to the screen mask. There was a problem that the paste remained partially, and thus the transferred solder paste amount varied and the bump size after heating and melting varied. In addition, there is a problem that adjacent solder pastes flow out and contact each other during heating and melting, which causes a bridge between the bumps and a large bump or a small bump.

In a method of placing a mask on an electronic component, filling the solder paste by printing on the electronic component, and heating and melting the solder paste while the mask is placed to form bumps, bumps are formed for each electronic component. Therefore, mass production was difficult. Further, there are problems that the solder filling amount of the mask varies due to the unevenness of the wiring on the electronic component, and the bleeding of the solder paste occurs.

In a method of filling a solder paste in a concave portion of a base material having a concave portion at a position facing a terminal electrode and mounting an electronic component thereon and heating and melting the same, etching is generally performed to form the concave portion of the base material. Although it is used, it is difficult to obtain the precision of the depth of the recess, and the material of the base material is limited to one that can be etched. Even when the recesses are machined, it is difficult to obtain the depth accuracy, and when the recesses are processed one by one, the manufacturing cost of the base material increases. Furthermore, after heating and melting the solder paste, the bumps formed in the recesses are fixed to the base material by the flux residue, and it is difficult to clean the flux residue in the recesses. When separated, there was a problem that the bump would be scratched or the bump might come off.

An object of the present invention is to prevent non-connection in an electronic component having a plurality of bumps when it is connected to a circuit board, improve connection reliability and product yield, and increase the degree of freedom in designing electronic components. It is to provide cheaper and higher-performance electronic components.

Still another object of the present invention is to provide a method of manufacturing an electronic component having a plurality of bumps, which is a low-priced and simple method, has a good bump size accuracy, and can improve reliability and yield. Another object is to provide a simple bump forming method.

[0012]

In order to solve the above-mentioned problems, an electronic component having a bump formed on a terminal electrode on the surface of the electronic component of the present invention has a flat portion on the circuit board side where the electronic component of the bump is mounted. In addition, when the bump forming surface of the electronic component faces upward, the bump apex position when the bump is formed into a heating sphere is the same as or higher than the flat portion position of the bump most protruding from the electronic component.

In addition, when the flat portion of the bump on the side of the circuit board on which the electronic component is mounted is flat and the flat portion position is controlled so that the flat portion is in the same plane, the bump is formed into a heating sphere. The bump top position is set higher than the bump flat position.

Further, the difference between the bump apex position when the bump is heated into a spherical shape and the flat portion position of the bump is made larger than the maximum warp size of the electronic component mounting area of the circuit board on which the electronic component is mounted. It is a thing.

Further, the volumes of the bumps are all made equal.

Further, in order to solve the above problems, the bump forming method for an electronic component in which bumps are formed on the terminal electrodes on the surface of the electronic component according to the present invention has through holes at positions corresponding to the terminal electrodes on the surface of the electronic component. One or more through-hole masks are stacked and fixed on the flat plate surface, the through-hole is filled with a metal paste or a conductive paste, the terminal electrode and the through-hole are positioned and mounted so that the paste is heated and melted. The bumps are formed by transferring to the terminal electrodes and removing the through hole mask and the flat plate.

In the bump forming method, the electronic component, the flat plate, the temperature lower than the melting point of the metal in the metal paste or the conductive substance in the conductive paste and higher than the curing temperature of the residue after the paste is heated and melted. The bumps are formed by heating at least one of the through-hole masks and removing the through-hole mask and the flat plate from the electronic component in that state.

Further, in the above bump forming method, when the paste is heated and melted and transferred to the terminal electrode, a gap is provided between the through hole mask and the electronic component, and the total of the gap and the thickness of the through hole mask. However, the height of the bump is made smaller than the height from the flat plate when the paste is heated and melted into spheres, and is larger than the height from the electronic component when the paste is heated and melted and transferred to the terminal electrodes of the electronic component to become spherical. To form.

Further, in the above bump forming method, the bumps are formed by removing the through hole masks on the surfaces of the plurality of stacked through hole masks before positioning so that the terminal electrodes and the through holes face each other. .

Furthermore, the hole shape of the through-hole mask is square, rectangular, or polygonal.

Further, the thickness of the through-hole mask is smaller than the height from the flat plate when the paste is heated and melted into spheres.

Further, the thickness of the through-hole mask is smaller than the height from the flat plate when the paste is heated and melted into spheres, and is larger than the bump height when the paste is heated and melted and transferred to the terminal electrodes of the electronic parts. is there.

Further, the through-hole mask is made of, for example, a polyimide material having flexibility.

Further, the flat plate is made of a flexible material.

Further, in the above bump forming method, the bump is formed by placing a weight on the electronic component before the paste is heated and melted and transferred to the terminal electrode.

Further, in the above bump forming method, the bump is formed by heating the electronic component and the through-hole mask at a temperature lower than the boiling point of the solvent of the paste and then cooling before placing a weight on the electronic component. is there.

According to the electronic component according to the above means, by flattening the portion of the bump on the circuit board side, it is possible to make contact when mounting the electronic component on the circuit board and increase the contact area. it can. Furthermore, the contact area can be further increased by controlling the position of the flat part so that the flat surface of this bump is in the same plane, which can prevent the positional deviation after mounting and improve the connection reliability and The yield can be improved.

Even if the electronic component is warped, the bump apex position when the bump having the flat portion is formed into a heating sphere is set to be the same as or higher than the flat portion position of the bump protruding most from the electronic component. Since all bumps come into contact with the connection electrodes of the circuit board when the bumps are heated and melted,
The bumps can be prevented from being unconnected, and the connection reliability and product yield can be improved. Furthermore, the bump apex position when a bump with a flat surface is made into a heating sphere is higher than the flat part position of the bump, and the difference is greater than the maximum warp size of the electronic component mounting area of the circuit board on which the electronic component is mounted. By increasing the size, even if the circuit board is warped, all the bumps come into contact with the circuit board during heating and melting of the bumps, so that it is possible to prevent unconnection of the bumps and further improve the connection reliability and the product yield. it can. In addition, since the warp of the electronic component and the warp of the circuit board can be ignored when designing the electronic component, the terminal electrode diameter and the bump size of the electronic component can be freely designed according to specifications such as electrical performance improvement. Since high functionality can be realized and the design margin is large, it is possible to use a common member with other electronic components, and as a result, a high-performance and inexpensive electronic component can be obtained.

Further, by making all the bumps have the same volume, for example, the solder supply amount for forming the solder bumps becomes the same for all the bumps, and the solder balls having the same diameter and the paste printing mask having the same hole diameter are used. Therefore, the device and the jig can be simplified and the manufacturing cost can be reduced.

Further, according to the electronic circuit bump forming method of the above means, for example, in the case of solder bumps, one or more through-hole masks having through-holes at positions corresponding to the terminal electrodes on the surface of the electronic component are overlaid on the flat plate surface. Fix, fill the through hole with solder paste, position so that the terminal electrode and the through hole face each other, heat and melt the solder paste to transfer to the terminal electrode, and form the bump by removing the through hole mask and flat plate Therefore, since the solder paste, which is cheaper than the solder ball, is used, the electronic component can be provided at a low price. Also, in order to put the mask on the flat plate instead of on the electronic circuit to fill the paste, for example, to perform paste printing,
It is possible to perform highly accurate solder printing in which the amount of the filling paste is uniform without being affected by unevenness or warpage on the electronic circuit. Further, if the size of the mask is set to a size corresponding to a plurality of electronic circuits, bumps can be simultaneously formed on a plurality of electronic circuits, and the number of manufacturing steps can be reduced. Further, by forming the paste filling portion with the through hole mask and the flat plate, the accuracy of the paste filling portion can be controlled by the mask thickness and the through hole diameter. Generally, the thickness and hole diameter can be maintained with high accuracy by an inexpensive method, so filling paste with high accuracy at low cost compared to the case of forming a recess in a base material whose accuracy is difficult to maintain. You can make a part to do.

When removing the through-hole mask and the flat plate from the electronic component, at least one of the electronic component, the through-hole mask, and the flat plate is placed at a temperature lower than the melting point of the solder and higher than the curing temperature of the paste residue such as flux. By heating, the bumps are not fixed due to the hardening of the flux residue, and the solder bumps can be easily separated without damaging them.

Further, a gap is provided between the electronic component and the through-hole mask, or after a plurality of through-hole masks are stacked, for example, paste printing is performed to fill the paste, and then the through-hole mask on the surface is peeled to remove the electrons. It is possible to prevent the parts other than the terminal electrode part of the component and the through-hole mask from coming into close contact with each other by a paste solvent such as flux. In addition, by forming the through-hole mask and the flat plate with a flexible material, it becomes possible to easily and gradually peel the electronic component from the edge. Further, by making the shape of the through hole square, rectangular or polygonal, the contact area between the bump and the through hole mask can be reduced and the adhesion can be reduced. Further, the thickness of the through-hole mask is smaller than the height from the flat plate when the paste is heated and melted into a sphere, and is larger than the height from the electronic component when the paste is heated and melt-transferred to the terminal electrodes of the electronic component and spheroidized. By doing so, the contact between the bump and the flat plate is eliminated, and the adhesion can be reduced. Due to the above effects, the electronic component, the through-hole mask, and the flat plate can be easily separated, the number of bump formation steps can be reduced, and as a result, the electronic circuit can be supplied at a low cost.

Further, by placing a weight on the electronic component before the paste is heated and melted and transferred to the terminal electrode, the displacement of the electronic component due to the foaming phenomenon generated by the evaporation of the solvent during the heating and melting of the paste is prevented. be able to. Also,
Before placing a weight on the electronic component, the electronic component and the circuit board can be heated at a temperature below the boiling point of the paste solvent and then cooled to temporarily fix the electronic component and the through-hole mask. It is possible to prevent the deviation of the electronic parts, and to improve the connection reliability and the yield.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a side view of an electronic component according to a first embodiment of the present invention. FIG. 5 is a side view for explaining the relationship between the flat portion position and the bump apex position when the electronic component of FIG. 1 is made into a heating sphere. FIG. 4 is a side view of the electronic component according to the second embodiment of the present invention. FIG. 6 is a side view for explaining the relationship between the flat portion position and the bump apex position when the electronic component of FIG. 4 is made into a heating sphere. FIG. 7 shows a process diagram for mounting and connecting the electronic component of the present invention on a circuit board having no warp. FIG. 8 shows a process diagram for mounting and connecting the electronic component of the present invention on a warped circuit board.

In FIG. 1, which is the first embodiment, bump flat portions 4 are provided on the terminal electrodes 2 of the electronic component 1 at the portions of the bumps 3 on the circuit board connection side, and the flat portions are in the same plane. It was done like this. The electronic component 1 is composed of, for example, an LSI, a printed board, a ceramics board, or the like. The terminal electrode 2 is made of, for example, a conductive metal such as Au, Al, Cu, W, and C.
It is formed by vapor deposition of r, Ni, Au and the like. Bump 3
Is, for example, Pb-Sn, Sn-Ag, Bi-Pb, Sn
It is composed of two or more kinds of metal alloys such as -Zn or a simple metal, and in some cases, a plurality of additives. As shown in FIG. 5, the bump flat portion position is controlled such that the bump flat portion position 22 is higher than the bump apex position 21 of the spheroidized bump 20 that is heated into a spherical shape. As a method of forming the bump flat portion 4, a softening temperature of the bump composition, for example, 183 in the case of eutectic solder having a bump composition of Sn63% Pb37%
It can be formed by pressing the bump vertices simultaneously on a plate heated to a temperature higher than 100 degrees. The pressing plate may be made of any material, such as ceramics, glass, or Teflon, which does not get wet with solder and can withstand the heating temperature. The bump flat portion 4 can also be formed by the bump forming method of the present invention.

As a second embodiment, FIG. 4 shows a bump flat portion 4 provided on the terminal electrode 2 of the electronic component 1 at a portion of the bump 3 on the circuit board connection side. Flat bumps 4
There are various positions. As a method of forming the bump flat portion 4, it is possible to form a flat portion by pressing a trowel that is not wet with the heated solder onto each apex of each bump. The bump flat portion position is controlled so that the bump flat portion position 22 most protruding from the electronic component is higher than the bump apex position 21 of the other spheroidized bump 20 that is heated into a spherical shape, as shown in FIG. .

Since the bumps 3 shown in FIGS. 1 and 4 are formed by the current solder bump formation or screen mask printing with the same mask hole diameters, the bumps 3 have substantially the same volume. For example, when a solder ball is used, the diameter variation of the solder ball having a diameter of 0.76 mm is about + -20 μm, and the volume variation is small.

A process of mounting and connecting the electronic component of the present invention on a circuit board having no warp will be described with reference to FIG. Here, the circuit board is a board such as a glass epoxy printed board, a flexible printed board, a glass board, or a ceramic board.

In FIG. 7A, the flux 7 is applied to the bump flat portion 4 of the bump 3 on the terminal electrode 2 of the electronic component 1.
As a method of applying the flux 7, there are a method of contacting and transferring the bump flat portion 4 to the flux pool, a method of applying with a brush, a method of applying with a dispenser, and the like. Figure 7
In (b), the bumps 3 of the electronic component 1 and the connection electrodes 6 of the circuit board 5 are positioned and mounted so as to face each other. Positioning mounting is possible with a commercially available flip chip bonder. The flux applied to the bump flat portion 4 in FIG. 7A may be applied to the connection electrode 6 of the circuit board 5 in FIG. 7B instead of the bump flat portion 4. As a flux applying method at this time, mask printing is a simple method. Also, solder paste or a reducing liquid may be used instead of the flux.

As can be seen from FIG. 7B, in the case of the electronic component of the first embodiment, since the bump flat portion 3 is in the same plane, the bump flat portion 3 is all in contact with the connection electrode 6. Further, since the contact is a surface contact, it is unlikely that the positional deviation occurs during transportation. Figure 7
By heating the entire electronic component 1 and the circuit board 5 in the reflow furnace 106 in (c), the connection bumps 9 that connect all the terminal electrodes 2 and the connection electrodes 6 are formed, so that the reliability and the yield are high. Connection is possible. Even when the electronic component of the second embodiment is used, as shown in FIG. 6, the bump flat portion position 22 that is most protruded from the electronic component is 22.
However, since it is controlled to be higher than the bump apex position 21 of the other spheroidized bump 20 that has been heated into a sphere, the bump flat portion that is not in contact comes into contact with the connection electrode when the spheroidized bump is melted into a sphere. A connection bump for connecting the terminal electrode and the connection electrode of is formed.

A process of mounting and connecting electronic parts on a warped circuit board will be described with reference to FIG. The electronic component 1 in which the flux 7 is applied to the same bump flat portion 4 as in FIG. 7A is positioned and mounted on the connection electrode of the warped circuit board 5 in FIG. 8A. At this time, due to the warp of the circuit board 5, a portion where the bump flat portion 4 and the connection electrode 6 are not in contact with each other occurs. However, as shown in FIG. 5, the electronic component of the present invention is controlled so as to be higher than the bump apex position 21 of the spheroidized bump 20 that has been spheroidized by heating. Therefore, in FIG. When the substrate 5 is heated in the reflow furnace 106, the bump flat portions that are not in contact with each other contact the connecting electrodes 6 when the bumps are melted into spheres, so that the connecting bumps 9 that connect all the terminal electrodes 2 and the connecting electrodes 6 are formed. To be done. Circuit board 5
If the warp is large, the position difference 23 between the bump apex position 21 and the bump flat portion position 22 of the sphered bump 20 that has been made into a heated sphere in FIG. 5, and the most protruding bump flat portion position 22 and the heating sphere in FIG. By controlling the flat portion position so that the positional difference 23 between the bumped sphered bump 20 and the bump apex position 21 is larger than the warp 31 of the connection electrode area, even if there is a warp, it is possible to ensure that the bump is heated and melted into a sphere. The contact bumps are formed by contacting the connection electrodes, and product reliability and yield can be improved. When forming the bump flat portion, it goes without saying that the bump flat portion position needs to be determined within a range in which adjacent bumps do not contact each other because the bump on which the flat portion is formed expands laterally. .

Next, as a third embodiment of the present invention, FIG.
A method of forming a eutectic solder bump on an electronic component will be described in detail with reference to.

FIG. 9 is a process drawing for forming bumps on the electronic component of the present invention.

In FIG. 9A, the through hole mask 101
A film made of a semi-transparent polyimide material is used as the material of, and has a heat resistance of about 400 degrees. The flat plate 100 is made of a glass material. Through hole 10
2 is a hole processed by an excimer laser. The shape of the through hole 102 is a circular through hole 300 as shown in FIG. First, the through-hole mask 101 is applied to the flat plate 10
Fix to 0 with heat resistant tape.

Next, referring to FIG. 9B, the through-hole mask 1
The through hole 102 of No. 01 is printed and filled with the eutectic solder paste 104 using a squeegee 103. If necessary, the filling state is observed from the surface of the flat plate 100 opposite to the fixing surface of the through-hole mask 101, and if there is an unfilled portion, the squeegee 10 is again used.
Print at 3.

Next, in FIG. 9C, the electronic component 1 made of a ceramic substrate is positioned so that the Au-plated terminal electrode 2 and the through hole 102 face each other, and the electronic component 1 is mounted on the through hole mask 101. . This positioning and mounting can be performed manually or automatically with a commercially available flip chip bonder. At the time of mounting, pressure is applied to the electronic component 1 to the extent that the electronic component 1, the through-hole mask 101, and the flat plate 100 are not damaged. If necessary, the positioning state is observed from the surface of the flat plate 100 opposite to the fixing surface of the through hole mask 101, and if the position of the through hole 102 and the position of the terminal electrode 2 are deviated, the positioning mounting is performed again.

Next, in FIG. 9D, the filling paste 105 is melted by being heated to about 200 degrees together with the flat plate 100 on which the electronic component is mounted in the reflow furnace, and transferred to the terminal electrode 2. Here, since the through-hole mask 101 and the flat plate 100 are both materials that do not get wet with solder, they are not transferred to a portion other than the terminal electrode 2.

Next, in FIG. 9E, the through hole mask 101 and the flat plate 100 are separated from the electronic component 1. The separation is performed by immersing the electronic component 1, the through-hole mask 101, and the flat plate 100 in the flux residue cleaning liquid.

Finally, if necessary, the flux residue or the like is again washed off the electronic component 1 to complete the bump formation of the electronic component. Further, since the bump has the bump flat portion 4 as shown in FIG. 1 depending on the thickness of the through hole mask, the reflow of the electronic component may be performed as needed.

In the above embodiment, the example of the eutectic solder paste is shown as the paste, but the paste is not limited to this, and for example, Pb-Sn, Sn-A.
g, Bi-Pb, Sn-Zn, etc., two or more kinds of metal alloys or simple metals, and in some cases, any paste as long as it is composed of a plurality of additives and is transferred to the electrode by heating and melting. Good. Also, as the electronic component, the electronic component 1 made of a ceramic substrate is shown as an example, but the electronic component made of, for example, a glass epoxy printed circuit board, a flexible printed circuit board, a glass substrate, etc., or another circuit board such as an unpackaged LSI Any electronic component that needs bumps for connection may be used.

Also, an example was shown in which a polyimide film was used as the through-hole mask 101 to make holes with a laser.
Through holes may be formed by a method such as alkali etching,
Further, the material of the through hole mask itself may be any material as long as it does not wet the solder, and for example, a through hole may be formed in a stainless plate or a glass plate by machining or etching. However, the conditions for material selection are that it withstands the heating temperature when solder is heated and melted, and that warpage is unlikely to occur. Moreover, there is no problem even if a plurality of through-hole masks are used by stacking them.

Although the circular through hole 300 is shown as an example of the shape of the through hole 102, the square through hole 301 as shown in FIG. 14 or the rectangular through hole 3 as shown in FIG.
It may be 02 or a polygonal shape. When the through hole mask 101 and the electronic component are slightly displaced, the heated and melted bumps come into contact with the wall surface of the through hole 102. In the case of the circular through hole 300, the bump 3 is formed on the wall surface of the circular through hole 300.
It becomes difficult to separate the electronic component and the through-hole mask from each other because of the line contact. In such a case, by using the square through hole 301 or the rectangular through hole 302, the contact between the bump 3 and the wall surface of the through hole is made a point contact, so that the separation can be facilitated.

Although an example using a glass plate as the flat plate 100 has been shown, any material can be used as long as it is a material that does not wet the solder and can form a flat surface, such as a ceramic plate or a stainless plate. I don't care. Further, by forming the flat plate 100 with a flexible material such as silicone rubber, when the flat plate 100 is separated from the through-hole mask 101, the flat plate is bent from the end as shown in FIG. Since the electronic component 1 and the through-hole mask 101 can be peeled off from the end as a result, the electronic component 1 and the through-hole mask 101 can be peeled off from the end.
The flat plate 100 can be easily separated.

Further, as an example of fixing the through-hole mask 101 and the flat plate 100 with a heat-resistant tape, a heat-peelable sheet having an adhesive surface between the through-hole mask 101 and the flat plate 100 or a heat-peelable sheet is used. Fixing with an adhesive, applying a solvent such as flux between the through-hole mask and the flat plate 100, and fixing using the adhesive force and surface tension of the through hole, or making a hole in the flat plate 100 or perforating the flat plate 100. Any method may be used as long as the through-hole mask 101 and the flat plate 100 can be fixed, such as a method of fixing the through-hole mask 101 by vacuum suction using a quality material. Flat plate 100
When a porous material is used, the atmosphere in contact with the paste at the time of heating and melting can be circulated, so that reduction of flux residue and reduction of voids in bumps can be expected.

Further, as the heating method for heating and melting the solder, an example of whole heating by the reflow furnace 106 is shown, but the whole using a hot plate, hot air, infrared rays, laser, or electronic component 1, through hole mask Local heating of 101, the flat plate 100, and the bumps 3 may be used. The heating atmosphere is an atmosphere or a heating atmosphere such as N2 or H2 that matches the characteristics of the paste used.

Further, in the present embodiment, the example in which the bump forming surface of the electronic component 1 faces downward is shown, but the bump forming surface of the electronic component 1 may face upward depending on the process. In this case, the effect that the voids in the bumps 3 are likely to come off the bumps 3 can be expected.

Furthermore, when the paste is heated and melted, a weight 303 may be placed on the electronic component 1 as shown in FIG. In this case, it is effective to prevent the shift of the electronic component 1 which may occur due to foaming caused by vaporization of the solvent when the paste is heated and melted. Before placing the weight 303 on the electronic component 1, the hot plate 20
Since the electronic component 1 and the through-hole mask 101 can be temporarily fixed by heating at a temperature of about 120 ° C. for 2 minutes and cooling to room temperature, the electronic component 1 is displaced when the weight 303 is placed. Can be prevented.

Next, as a fourth embodiment of the present invention, FIG.
A method for forming solder bumps on electronic components will be described using 0.

FIG. 10 is a process chart for forming bumps on the electronic component of the present invention. The spacer 1 shown in FIG.
Reference numeral 50 is for providing a gap between the through hole mask 101 and the electronic component 1 so that the through hole mask 101 and the electronic component 1 do not come into contact with each other. The thickness of the spacer 150 is the same as that of the flat plate 100 when the filling paste 105 is heated and melted into spheres.
It is necessary to make the height smaller than the value obtained by subtracting the thickness of the through hole mask 101 from the height.

In FIG. 10A, the through hole mask 10
After solder printing on the through hole 102 of No. 1, through hole mask 1
The spacer 150 is placed on 01. Where spacer 1
The position of 50 is adjusted so that it does not come over the through hole 102. Next, the electronic component 1 is positioned so that the terminal electrode 2 and the through hole 102 face each other, and the electronic component 1 is mounted on the spacer 150. At this time, the electronic component 1, the spacer 150, and the through-hole mask 101 must be sufficiently adhered so that the gap between the electronic component 1 and the through-hole mask 101 becomes the thickness of the spacer.

In FIG. 10B, the reflow furnace 106
To heat and melt the filling paste 105 and transfer it to the terminal electrode 2.

In FIG. 10C, the electronic component 1, the through hole mask 101, the spacer 150 and the flat plate 100 are separated. Here, since there is a gap between the through hole mask 101 and the electronic component 1 due to the spacer 150, the surface of the through hole mask 101 and the electronic component 1 will not be adhered by flux residue, etc. It can be done easily and does not damage the bumps 3. Also, if the electronic component 1 can be separated from the through-hole mask 101, the through-hole mask 101 made of a flexible polyimide material can be pulled up from the flat plate 100 from the end and peeled off, and the separation is easy.

Here, further, the thickness of the spacer 150 is set to the flat plate 10 when the filling paste 105 is heated and melted into spheres.
It is smaller than the value obtained by subtracting the thickness of the through-hole mask 101 from the height from 0, and is larger than the height from the electronic component 1 to the apex of the bump 3 when the bump 3 is formed in a spherical shape on the terminal electrode 2. By doing so, in FIG. 10B, the apex of the bump 3 and the flat plate 100 are no longer in contact with each other,
In FIG. 10C, the electronic component 1 can be separated more easily.

Although the spacer 150 is used to form a gap between the electronic component 1 and the through-hole mask 101 in the above embodiment, any method may be used to form this gap. Alternatively, for example, the gap between the electronic component 1 and the through-hole mask 101 may be provided by suspending the electronic component from above and controlling the suspension height.

Next, as a fifth embodiment of the present invention, FIG.
A method of forming solder bumps on an electronic component will be described with reference to FIG.

FIG. 11 is a process drawing of filling a through hole mask with solder paste. In FIG. 11A, the through-hole mask 101A and the through-hole mask 101B are superposed and fixed on the flat plate 100. Next, in FIG. 11B, the through holes 102A, 1A
02B is filled with the solder paste 104 by paste printing. Here, on the surface of the through-hole mask 101B, paste solvent such as flux and solder particle residue due to printing unevenness exist. Next, the through-hole mask B is removed in FIG. Next, as shown in FIG. 11D, the electronic component 1 is positioned and mounted on the through-hole mask 101A, and thereafter, bumps are formed in the same manner as the process shown in the third embodiment.

By removing the through-hole mask 101B, the solder solvent such as flux adhered to the surface of the through-hole mask during paste printing and the solder particle residue due to printing unevenness can be removed together with the through-hole mask 101B. Even if the surface and the surface of the through-hole mask 101A come into contact with each other, the adhesive force does not work, and the electronic component after heating and melting and the through-hole mask are easily separated.

In the above embodiment, the through-hole mask has been described as the two through-hole masks 101A and 101B.
Further, a plurality of through-hole masks may be stacked, and one or more through-hole masks to be removed may be removed from the surface.

Next, as a sixth embodiment of the present invention, FIG.
A method of forming solder bumps on an electronic component will be described with reference to 2.

FIG. 12 is a process diagram for separating the electronic component having the bumps transferred to the terminal electrodes from the through-hole mask. FIG.
2 (a), the flat plate 1 is formed by the hot plate 202.
The whole is heated to about 120 degrees via. This heating softens the flux residue. In FIG. 12B, the suction jig 201 is brought into contact with the electronic component 1 and the vacuum suction 201
Thus, the electronic component 1 is adsorbed to the adsorption jig 201. FIG.
The electronic component 1 and the through-hole mask 101 are separated by pulling up the electronic component 1 above the through-hole mask while adsorbing the electronic component 1 to the suction jig 201 in 2 (c). Since the flux residue is softened, it can be easily separated.

In the above embodiment, the flux residue was softened by the hot plate 202.
By heating the pulse heater 203 attached to 0, heating via electronic components may be performed. Further, other laser, hot air, infrared ray, or other heating method may be used.

Further, the structure of the above embodiment can be used as it is even in the step of heating and melting the paste to form the bumps 3 on the terminal electrodes 2. In that case, the hot plate 2 is used.
02 or the heating temperature of the pulse heater 203 is set to 183 ° C. or higher, which is the melting point of the bump 3.

Needless to say, the heating temperature varies depending on the solder composition used and the type of flux.

[0075]

As described above, according to the present invention, by providing a flat portion on a bump in an electronic component in which a bump is formed on a terminal electrode on the surface of the electronic component, it is possible to prevent unconnection at the time of connection with a circuit board. Since the connection reliability and the product yield can be improved and the degree of freedom in designing the electronic component can be increased, it is possible to provide a more inexpensive and highly functional electronic component.

Further, according to the present invention, one or more through-hole masks having through-holes at positions corresponding to the terminal electrodes on the surface of the electronic component are stacked and fixed on the flat plate surface, and the through-holes are filled with paste. The electronic component is positioned and mounted on the through-hole mask so that the terminal electrode and the through-hole face each other, the paste is heated and melted and transferred to the terminal electrode, and the bump is formed by removing the through-hole mask and the flat plate from the electronic component. For this reason, the bump size accuracy is far better than the bump forming methods known up to now, and electronic components with high electrical connection reliability without scratches or dropping of the bumps can be manufactured with a simpler manufacturing process at a lower price. It can be manufactured in large quantities and with high yield. Therefore, the present invention is extremely advantageous for manufacturing electronic components in which the size and pitch of bumps are miniaturized.

[Brief description of drawings]

FIG. 1 is a side view of an electronic component according to a first embodiment of the present invention.

FIG. 2 is a side view of a conventional electronic component.

FIG. 3 is a side view of a process of mounting and connecting a conventional electronic component on a circuit board.

FIG. 4 is a side view of an electronic component according to a second embodiment of the present invention.

FIG. 5 is a side view showing the relationship between the bump apex position and the flat portion position of the electronic component of the first embodiment.

FIG. 6 is a side view showing a relationship between a bump apex position and a flat portion position of the electronic component of the second embodiment.

FIG. 7 is a process side view of mounting and connecting the electronic component according to the present invention on a circuit board without warpage.

FIG. 8 is a process side view of mounting and connecting the electronic component according to the present invention on a warped circuit board.

FIG. 9 is a process side view showing a bump forming method for an electronic component according to a third embodiment of the present invention.

FIG. 10 is a process side view showing a bump forming method of an electronic component according to a fourth embodiment of the present invention.

FIG. 11 is a side view of the step of filling the through-hole mask with solder paste in the bump forming method for electronic components according to the fifth embodiment of the present invention.

FIG. 12 is a process side view for separating an electronic component from a through hole mask in a bump forming method for an electronic component according to a sixth embodiment of the present invention.

FIG. 13 is a plan view of a through hole mask having circular through holes.

FIG. 14 is a plan view of a through hole mask having square through holes.

FIG. 15 is a plan view of a through hole mask having a rectangular through hole.

FIG. 16 is a side view in which a weight is placed on the electronic component.

FIG. 17 is a side view when the through-hole mask and the flat plate are peeled off.

[Explanation of symbols]

1 ... Electronic parts, 2 ... Terminal electrodes, 3 ... Bumps, 4 ...
… Bump flat area, 5 …… Circuit board, 6 …… Connecting electrode, 1
0 ... Bump spherical part, 20 ... Spherical bump, 21 ...
Bump apex position, 22 ... Bump flat position, 23 ...
Positional difference, 24 …… Position of most protruding bump flat part, 31 ……
Circuit board warp, 100 ... Flat plate, 101 ... Through hole mask, 102 ... Through hole, 103 ... Squeegee, 10
4 ... Solder paste, 105 ... Filling paste, 1
06: Reflow furnace

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Wai, No. 1 Horiyamashita, Hadano-shi, Kanagawa Hitachi, Ltd. General-purpose computer division (72) Inventor Kaoru Katayama No. 1, Horiyamashita, Hadano-shi, Kanagawa Hitachi, Ltd. General-purpose computer division (72) Inventor Isamu Takaoka No. 1 Horiyamashita, Hadano-shi, Kanagawa Hitachi Ltd. General-purpose computer division (72) Inventor Kosuke Inoue 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. In-house (72) Inventor Hitoshi Odajima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock Company Hitachi, Ltd.

Claims (19)

[Claims] 1. An electronic component having a bump formed on a terminal electrode on the surface of the electronic component, wherein the portion of the bump on the side of a circuit board on which the electronic component is mounted is flat and the bump is formed into a heating sphere. An electronic component, wherein a bump apex position when the bump forming surface is directed upward is the same as or higher than a flat portion position of the bump most protruding from the electronic component. 2. The electronic component according to claim 1, wherein a difference between a bump apex position when the bump is heated into a sphere and a highest flat portion position of the bump is an electronic component of a circuit board on which the electronic component is mounted. An electronic component characterized by being larger than the maximum warp size of the mounting area. 3. An electronic component having a bump formed on a terminal electrode on the surface of the electronic component, wherein a portion of the bump on the circuit board side on which the electronic component is mounted is flat and the flat portion is in the same plane. The electronic part is characterized in that the position of the flat part is controlled in such a way that the lowest bump apex position when the bump forming surface of the electronic part when the bump is heated into a sphere is upward is higher than the position of the flat part of the bump. . 4. The electronic component mounting area of a circuit board on which the electronic component is mounted, wherein the difference between the bump apex position and the flat portion position of the bump when the bump is heated into a spherical shape. An electronic component characterized by being larger than the maximum sled size of. 5. The electronic component according to claim 1, wherein the bumps have substantially the same volume. 6. One or more through-hole masks having through-holes at positions corresponding to the terminal electrodes on the surface of the electronic component are stacked and fixed on the flat plate surface, and the through-holes are filled with a metal paste or a conductive paste. The electronic component is positioned and mounted on the through-hole mask so that the terminal electrode and the through-hole filled with the metal paste or the conductive paste face each other, and the metal paste or the conductive paste is heated and melted to form the terminal electrode. A bump forming method for an electronic component, which comprises: forming a bump by removing the through hole mask and the flat plate from the electronic component. 7. The bump forming method according to claim 6,
At least the melting point of the metal in the metal paste or the conductive material in the conductive paste and the temperature higher than the curing temperature of the residue of the metal paste or the conductive paste after heating and melting of the metal paste, the flat plate, and the through-hole mask. A method for forming bumps for an electronic component, comprising heating one or more and removing a through-hole mask and a flat plate from the electronic component in that state. 8. The bump forming method according to claim 6,
A bump forming method for an electronic component, wherein a gap is provided between the through-hole mask and the electronic component when the metal paste or the conductive paste is heated and melted and transferred to the terminal electrode. 9. The bump forming method according to claim 8,
The bump of the electronic component, wherein the thickness of the through-hole mask and the total value of the gap between the through-hole mask and the electronic component are smaller than the height from the flat plate when the metal paste or the conductive paste is heated and melted into a sphere. Forming method. 10. The bump forming method according to claim 9, wherein the thickness of the through-hole mask and the total value of the gap between the through-hole mask and the electronic component are such that the metal paste or the conductive paste is heated and melted on the terminal electrode of the electronic component. A bump forming method for an electronic component, wherein the height is greater than the height from the electronic component when transferred and made into a sphere. 11. The bump forming method according to claim 6, wherein before the electronic component is positioned and mounted on the through-hole mask such that the terminal electrode and the through-hole face each other, the surface of the plurality of through-hole masks is penetrated. A method of forming a bump for an electronic component, which comprises removing a hole mask. 12. A bump forming method for an electronic component, wherein the flat plate according to claim 6 is made of a flexible material. 13. A bump forming method for an electronic component, wherein the through-hole mask according to claim 6 has flexibility. 14. A bump forming method for an electronic component, wherein the through-hole mask according to claim 13 is made of a polyimide material. 15. A bump forming method for an electronic component, wherein the through-hole shape of the through-hole mask according to claim 6 is a square, a rectangle or a polygon. 16. The through-hole mask according to claim 6, wherein
A bump forming method for an electronic component, characterized in that the height of the metal paste or the conductive paste from the flat plate when heated and melted into spheres is smaller. 17. The thickness of the through-hole mask according to claim 6,
An electron characterized in that the height of the metal paste or the conductive paste is smaller than the height from the flat plate when it is spheroidized by heating, and is larger than the height from the electronic component when it is spheroidized by being heat-melted and transferred to the terminal electrode of the electronic component. Bump forming method for components. 18. The bump forming method according to claim 6, wherein a weight is placed on the electronic component before the metal paste or the conductive paste is heated and melted and transferred to the terminal electrode. Bump forming method. 19. The bump forming method according to claim 18, wherein the electronic component and the through-hole mask are heated and cooled at a temperature lower than the boiling point of the solvent of the metal paste or the conductive paste before the weight is placed on the electronic component. A method of forming a bump for an electronic component, comprising: