JP2001308513A - Method for restoring electronic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for restoring electronic circuit board by which the defective continuity between a substrate and electronic parts caused by the insufficient printed amounts of solder bumps can be reduced. SOLUTION: In the solder paste printing step of this method for restoring electronic circuit board, a screen mask 10 is removed from a CSP 4 after the solder melting treatment by means of hot air 8 and solder hardening treatment by means of blown air 15 are performed on the solder paste filling up the holes 10a of the screen mask 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit board for performing a step of removing a mounted electronic component from a board and a step of mounting the removed electronic component or another electronic component in a component removal area of the board. It relates to the repair method.

[0002]

2. Description of the Related Art Conventionally, this type of electronic circuit board repairing method (hereinafter referred to as "repair") for removing and remounting electronic components has been performed by a quality test on a mother board such as a PWB (Printed Wiring Board). There is a method for exchanging an electronic component for which a determination has been made with another one. BGA
(Ball Grid Array), LGA (Land Grid Array), CSP
For semiconductor devices, such as (Chip Size Package), in which it is difficult to temporarily connect the so-called pin bonding electrode to the quality test device, the quality test is performed after mounting on the motherboard in this way. Is often performed to replace the semiconductor device.

There is also a repair in which an electronic component once removed from a mother board is mounted again on the mother board. For example, when a defect is suspected in the quality test on the mother board, but there is actually no abnormality in the electronic component itself, such an electronic component is repaired.

In recent years, semiconductor devices, such as LGA, BGA, and CSP, have more bonding electrodes than those having lead terminals protruding in a gull-wing shape from the package side surface, such as QFP (Quad Flat Pack). Devices having microelectrodes arranged in an array on the lower surface of the package are becoming mainstream. In the latter semiconductor device, since the bonding electrode is provided on the lower surface of the package, it is not necessary to adopt a complicated three-dimensional structure such as a gull wing structure, so that the bonding electrode can be a minute electrode. As a result, the number of I / Os can be increased without increasing the size of the package.

[0005] In the process of mounting a semiconductor device having such minute electrodes on a mother substrate, a solder paste printing method may be used. For example, in an LGA having flat electrodes as microelectrodes, solder projections are printed on each of the microelectrodes by a solder paste printing method, or a plurality of solder projections are printed on a pad as an electrode pattern on a motherboard. Then, after mounting the LGA on the motherboard so that the solder projections and the pads are overlapped, the solder particles in the solder projections are melted by a reflow furnace method, hot air irradiation, laser irradiation, or the like. Further, the flattened electrode and the pad of the motherboard are connected by soldering by curing the melted solder. Further, for example, each bonding electrode is a protruding electrode (bump electrode) protruding from the lower surface of the package, and even in a BGA or CSP in which this protruding electrode is formed of a solder ball, the positional deviation on the mother board after mounting is reduced. In some cases, solder protrusions corresponding to the respective protruding electrodes are printed on the pads of the mother board for the purpose of reducing the amount of light or exhibiting a more reliable solder connection.

[0006]

However, in the conventional solder paste printing method, for example, after filling each hole of a stencil mask closely adhered to a mother substrate with a solder paste, the stencil mask is peeled off from the mother substrate. Since a part of the solder paste in the hole is dragged by the inner wall of the hole, untransferred solder paste remains in each hole. As a result, the printed amount of the solder protrusion is insufficient, and as a result, there is a problem that the solder bonding between the pad of the mother board and the bonding electrode of the electronic component becomes insufficient, resulting in poor conduction. In particular, in repair, a so-called printing device cannot be used because electronic components mounted around the component removal area on the motherboard are in the way, and solder paste printing is performed manually. Often. For this reason, it is not possible to delicately adjust the printing pressure, the plate separation speed when the stencil mask is peeled off from the mother substrate, and the like, and the printing amount shortage described above tends to occur.

Although this is a problem when a stencil mask is used in the solder paste printing method, a similar problem may occur even when an intaglio mask is used.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce poor conduction between a substrate and an electronic component caused by a shortage of a printed amount of a solder projection. An electronic circuit board repair method is provided.

[0009]

In order to achieve the above object, the invention according to claim 1 includes a step of removing a mounted electronic component from a substrate, and a step of forming a solder bump on an electrode pattern in a component removal region of the substrate. And a mounting step of mounting the electronic component or another electronic component on the substrate such that the bonding electrode and the solder projection overlap, and melting the solder in the solder projection by heating. In a method for repairing an electronic circuit board, a melting step of causing the molten solder to be hardened by cooling and a hardening step of solder-connecting the electrode pattern and the bonding electrode is performed. After subjecting the solder paste to a solder melting process by heating and a solder hardening process by cooling, the stencil or intaglio that had been in close contact with the substrate was peeled off from the substrate to remove the solder bumps. It is characterized in that print.

[0010] In the present electronic circuit board repairing method, the “solder paste in a stencil or intaglio” refers to a solder paste in a hole of a stencil or a solder paste in a recess of an intaglio.

In this method of repairing an electronic circuit board, in a printing step of printing solder projections, prior to peeling off a stencil or intaglio filled with solder paste into each hole or recess from the board, solder particles in the solder paste are removed. Is melted and hardened.
The melting and hardening causes the solvent in the solder paste to evaporate in each of the holes or the concave portions, to cause fusion of the solder particles, and the like, and to change the solder paste from the paste into a solder solid. The solder solids that are modified in this way are integrated with the individual solder particles by fusion, and are also solidified with the electrode pattern of the substrate. In addition, it shrinks due to volatilization of the solvent and the like, and deforms into a rounded shape due to surface tension and the like generated when the solder particles fuse. Then, such contraction and deformation significantly reduce the contact area with the inner wall of the hole or the inner wall of the recess. Furthermore, the solidified solid after modification loses almost all its viscosity due to solidification. As a result of the fusion / integration, the reduction of the contact area, and the disappearance of the viscosity as described above, the frictional force between the inner wall of the hole or the inner wall of the concave portion generated when the stencil or the intaglio is separated from the substrate is significantly reduced, It smoothly escapes from the hole or recess and is transferred and printed on the substrate to become a solder projection. In such a configuration, the removability of the solder solid from the hole or the concave portion is improved, and the shortage of the printed amount of the solder protrusion on the substrate (electrode pattern) is reduced. The solder projections made of the solder solid are melted and hardened again in the melting step and the hardening step.

According to a second aspect of the present invention, there is provided the electronic circuit board repair method according to the first aspect, wherein the soldering particles of the solder paste in the stencil or the intaglio are melted in the printing step. Instead, the solder paste is heated at a temperature lower than the melting point of the solder particles to volatilize the solvent in the solder paste.

In this method for repairing an electronic circuit board, in the printing step, instead of melting the solder particles in the solder paste, the solder paste is heated at a temperature lower than the melting point of the solder particles and contained therein. The solvent used is volatilized. Then, by this volatilization, at least the outer portion of the solder paste is solidified. The present inventors have earnestly studied and found that, when the solder paste is solidified in this way, it is possible to improve the removability of the solder paste from the holes or recesses and reduce the shortage of the printed amount of the solder protrusion on the substrate. Was.
Also, unlike the solder solid after modification in the method for repairing an electronic circuit board according to claim 1, the solidified solder paste does not fuse individual solder particles,
No change in shape due to surface tension at the time of solder particle fusion. For this reason, the roundness of the tip of the solder protrusion after printing is smaller than that of the solder protrusion of the first aspect, and the contact area of the electronic component with the joining electrode is increased. Such solder projections are more reliably brought into contact with the electronic component (joining electrode), and the solder particles are melted and hardened. The reason for improving the solder paste removability in the present electronic circuit board repair method is to reduce the adhesiveness between the outer portion and the inner wall of the hole or the inner wall of the recess by solidifying at least the outer portion of the solder paste. Is considered to be involved.

According to a third aspect of the present invention, there is provided a method for removing a mounted electronic component from a substrate by a solder paste printing method using a stencil or an intaglio, and solder bumps are formed on the bonding electrodes of the electronic component or another electronic component. A printing process to print the
A mounting step of mounting the electronic component that has undergone the printing step on a component removal area of the substrate such that the solder protrusion and the electrode pattern of the substrate overlap, and a melting step of melting the solder in the solder protrusion by heating And a curing step of curing the melted solder by cooling to solder-connect the electrode pattern and the bonding electrode, wherein the solder paste in the stencil or intaglio is used in the printing step. After performing a solder melting process by heating and a solder hardening process by cooling, the stencil or intaglio that had been in close contact with the electronic component was peeled off from the electronic component to print the solder protrusions. Is what you do.

In this method of repairing an electronic circuit board, the same effect as in the method of repairing an electronic circuit board according to the first aspect is used to improve the removability of the solder paste from the holes or recesses, and to the electronic component (joining electrode). Insufficient printing amount of the solder protrusion is reduced.

According to a fourth aspect of the present invention, in the method for repairing an electronic circuit board according to the third aspect, in the printing step, the solder paste of the solder paste in the stencil or the intaglio is not melted, It is characterized by heating at a temperature lower than the melting point to volatilize the solvent in the solder paste.

In this method of repairing an electronic circuit board, the same effect as that of the method for repairing an electronic circuit board according to the second aspect is used to improve the removability of the solder paste from the holes or recesses, and to reduce the possibility of solder projections on the electronic component. Reduce print volume shortage.
Further, the solder particles are melted and hardened while the solder projections are brought into contact with the board more reliably than in the electronic circuit board repair method of the third aspect.

According to a fifth aspect of the present invention, there is provided an electronic circuit board for performing a removing step of removing a mounted electronic component from a board and a mounting step of mounting the electronic component or another electronic component in a component removing area of the board. In the repair method, an electronic component having a plurality of projecting electrodes projecting from the lower surface of the main body as bonding electrodes is mounted on the substrate, and, in the mounting step, each of the holes of the stencil is formed on the electrode pattern on the substrate. A contacting step of bringing the stencil into close contact with the substrate so as to match the corresponding position, a filling step of filling each hole of the stencil with the solder paste, and placing each of the protruding electrodes by placing the electronic component in the component removal area A mounting step of inserting the tips of the holes into the corresponding holes of the stencil, a melting step of heating the solder paste in each hole to melt the solder particles in the solder paste, The solder was allowed to cure by cooling and is characterized in that for implementing a curing step of soldering connection between the electrode pattern and the protrusion electrodes.

In this electronic circuit board repairing method, a stencil similar to the stencil in the solder paste printing method is used in a mounting step of mounting an electronic component on a board. However, after each hole of the stencil is filled with solder paste by squeezing or the like, the stencil and the substrate are not separated as in the conventional solder paste printing method, and the stencil is left as it is on the substrate. Next, the electronic component is placed on the stencil such that the tips of the protruding electrodes projecting from the lower surface of the main body of the electronic component are respectively inserted into the corresponding holes of the stencil. Then, the solder particles of the solder paste in each hole are melted and hardened, and each protruding electrode previously inserted into each hole is electrically and mechanically soldered to the electrode pattern of the substrate. In such a configuration, without separating the stencil from the substrate, the entire amount of the solder in the solder paste filled in each hole of the stencil contributes to the solder connection between the electrode pattern of the substrate and the protruding electrode of the electronic component. Therefore, it is possible to eliminate poor conduction between the substrate and the electronic component caused by the insufficient printed amount of the solder protrusion.
However, in the electronic circuit board repair method, it is not possible to use, as an electronic component to be mounted in the mounting process, a bonding electrode having a flat electrode that cannot be inserted into a hole of a stencil, such as an LGA. .

According to a sixth aspect of the present invention, in the electronic circuit board repair method of the fifth aspect, an electronic component having a plurality of flat electrodes provided on the lower surface of the main body instead of the protruding electrodes as the bonding electrodes is mounted. In addition, prior to the placing step, a printing step of printing solder projections on each flat electrode by a solder paste printing method using a stencil or an intaglio is performed.

In this method of repairing an electronic circuit board, an electronic component having a plurality of flat electrodes disposed on the lower surface of the main body is used as an electronic component to be mounted in the mounting step. And
A plurality of solder protrusions are printed on each flat electrode by a solder paste printing method using a stencil or an intaglio, and then the above-described placement step is performed. In such a configuration, for example, even in the case of an electronic component such as an LGA, it is possible to insert the solder projections formed on the flat electrodes into the respective holes of the stencil on the substrate. Therefore, it is possible to mount electronic components by soldering each flat electrode and the electrode pattern of the substrate. However,
In the method for repairing an electronic circuit board according to the fifth aspect, it is possible to eliminate the conduction failure between the board and the electronic component caused by the insufficient printed amount of the solder protrusion. As a result of the insufficient printed amount of the solder projection on the flat electrode, a new problem of causing the conduction failure may occur.

According to a seventh aspect of the present invention, in the method of repairing an electronic circuit board according to the sixth aspect, in the printing step, the solder paste in the stencil or intaglio adhered to the electronic component is subjected to a solder melting process by heating. After performing a solder hardening treatment by cooling, or after heating the solder paste at a temperature lower than the melting point of the solder particles to volatilize the solvent in the solder paste, the stencil or intaglio is removed from the electronic component. And printing the solder protrusions.

In this method of repairing an electronic circuit board, the shortage of printed solder bumps on the electronic component is reduced by the same operation as the above-mentioned method of repairing an electronic circuit board.
Therefore, it is possible to reduce new conduction defects caused by the shortage of the print amount.

In some cases, it is necessary to change the electrode pattern of the substrate when repairing an electronic component. For example, there is a case where a design change of the electrode pattern occurs after mounting, or a case where a defect of the electrode pattern is found.
However, in general, many electrode patterns are formed on a surface mounting substrate in a region where the substrate is brought into close contact with an electronic component.
If a new wiring or the like is added in this region, there is a possibility that mounting of the electronic component becomes difficult because, for example, a plurality of bonding electrodes (protruding electrodes or flat electrodes) are short-circuited.

Therefore, the invention of claim 8 is based on claims 5 and 6
Or the electronic circuit board repair method according to 7, wherein the stencil used in the close contacting step has holes shaped so as to face two or more independent electrodes of the electrode pattern,
The solder particles in the solder paste filled in the holes are melted and hardened so as to short-circuit these electrodes in the hardening step.

In this method of repairing an electronic circuit board, a stencil having a hole capable of facing two or more independent electrodes included in the electrode pattern of the board is used. Then, the solder particles in the solder paste filled in the holes are melted and hardened in the melting step and the hardening step, and these electrodes are electrically short-circuited. In such a configuration, any electrode in the electrode pattern can be short-circuited to change the electrode pattern while avoiding undesired short-circuiting of the bonding electrode of the electronic component. In addition, a relatively large solder projection that short-circuits two or more electrodes generally tends to cause so-called sagging on the substrate when the solder particles are melted and hardened.
As a result, a short circuit failure or an undesired short circuit may occur. However, in the electronic circuit board repairing method, the above-mentioned sagging can be avoided by melting and hardening the solder particles in the solder paste in the holes of the stencil, and these short-circuit defects and unintended short-circuits can be prevented.

The ninth aspect of the present invention is the first aspect of the present invention.
4. The method of repairing an electronic circuit board according to 4, 5, 6, 7 or 8, wherein a stencil or an intaglio used in the printing step is made of a resin material in which holes or recesses are ablated in a resin material. It is.

In this method of repairing an electronic circuit board, a resin stencil or intaglio having a hole or a recess formed by ablation, such as a so-called plastic mask, is used in the printing step. In such a stencil or intaglio, for example, such as a metal mask, having a hole or recess processed by a photolithography method or an etching method,
The smoothness of the inner wall of the hole and the inner wall of the concave portion is far superior. Therefore, the frictional force between the solder solid or the solidified solder paste and the inner wall of the hole or the inner wall of the recess is smaller than that of a metal mask or the like. Thus, the removability of the solder solids and the like from the inside of the hole or the concave portion is improved, and the shortage of the printed amount of the solder protrusion is reduced. However, resin stencils and intaglios are more liable to be deformed by heating than metal stencils, and this deformation may cause a new problem of causing defective printing positions of solder projections.

Therefore, a tenth aspect of the present invention is the electronic circuit board repair method according to the ninth aspect, wherein a polyimide resin is used as the resin material.

In this method of repairing an electronic circuit board, a stencil or intaglio made of polyimide resin having heat resistance is used.
The stencils and intaglios having such a configuration have less deformation due to heating than those made of other resins. In particular, the melting point of solder particles, 2
Heating at about 00 ° C. causes almost no deformation. For this reason, it is possible to reduce the defective printing position of the solder projection due to the deformation of the stencil or the intaglio caused by the heating.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an embodiment to which the present invention is applied, an electronic circuit board repairing method (hereinafter, referred to as "repair") for removing and mounting a CSP will be described.

First, the repair of the first embodiment will be described. FIG. 1 is a perspective view showing a mother substrate to be repaired according to the first embodiment. In the figure, a mother board 1 made of PWB or the like has a bare chip 2, a QFP 3,
Electronic components such as CSP4 are mounted. The mother board 1 is repaired because the operation failure of the CSP 4 is confirmed by a known quality test method.

In this repair, the work is carried out in the order of the removal process of the mounted CSP 4, the solder paste printing process, the mounting process as the mounting process, the reflow process as the melting process, and the curing process. The order of the removing step and the solder paste printing step may be reversed.

FIGS. 2A to 2C are explanatory diagrams showing the work flow of the above-mentioned removing step. In the cross section of FIG. 2A, the mother substrate 1 has a plurality of substrate electrodes 1a as an electrode pattern, and is fixed on a metal stage 6 by fixing means (not shown). The CSP 4 mounted on the mother substrate 1 has I / O pads 4b arranged in an array on the lower surface of the package 4a. The mother substrate 1 and the CSP 4
a and each pad 4b are electrically and mechanically connected by soldering individually via the solder 5. The CSP 4 thus connected is connected to the mother board 1
In order to remove the solder connection, first, the solder 5 interposed between each substrate electrode 1a and each pad 4b must be melted to release the solder connection. Therefore, as shown in FIG. 2B, hot air 8 is blown from the hot air nozzle 7 toward the upper surface of the CSP 4 and the stage 6 is heated by a heating means such as a heater (not shown), so that the CSP side and the substrate side are heated. Are heated and melted from both. Then, the CSP 4 is sucked from above with vacuum tweezers 8 as shown in FIG. After the removal, the solder 5 remaining on the board is melted by a soldering iron and sucked by a solder wick, for example, to be completely removed from the mother board 1.

The substrate electrode 1a and the pad 4b
As a method for melting the solder 5 connecting the substrate and the substrate 5, a method of putting the mother substrate 1 into a reflow furnace, a method of irradiating a laser, or the like may be used. In addition, CSP after solder melting
For example, a clamper or the like may be used as a means for removing the cover 4.

FIGS. 3 (a) to 3 (c) and FIG. 4 (a)
(C) is an explanatory diagram showing a work flow of the solder paste printing step. In FIG. 3A, reference numeral 4 denotes a new CSP 4. The new CSP includes a bump electrode on which a solder ball 4c is welded on each pad 4a. In the solder paste printing step, such a new CSP 4 is first set on the positioning jig 9 such that the lower surface thereof faces upward. Then, as shown in FIG. 3B, a screen mask 10 as a stencil is brought into close contact with the CSP 4, and then from above the screen mask 10 using a squeegee 11 as shown in FIG. The solder paste 12 is filled in each of the holes 10a. The solder paste 12 contains a myriad of solder particles and a flux that removes an oxide film of the solder particles when the solder is melted. Further, the flux contains a resin component and a solvent. I have.

In the solder paste printing step, it is desirable to apply a flux to the solder balls 4c of the CSP 4 before the screen mask 10 is brought into close contact with the CSP 4. According to the experiments of the present inventors, by applying the flux in this manner, the peripheral portion of each hole 10a of the screen mask 10 and the solder ball 4
The adhesiveness with the solder paste 12 was improved, and the bleeding of the solder paste 12 from each hole 10a in the subsequent filling of the solder paste 12 could be suppressed. As a result, a short circuit between the electrodes caused by the bleeding of the solder paste 12 was significantly reduced.

When the operation of FIG. 3C is completed, next, FIG.
As shown in FIG. 1A, a hot air nozzle 7 is provided above a screen mask 10, and hot air 8 is blown from the hot air nozzle 7 toward the screen mask 10 to remove solder fine particles in the solder paste 12 filled in each hole 10a. Let melt. And
As shown in FIG. 4B, after removing the hot air nozzle 7,
Blow 15 is applied to screen mask 10 by blowing means (not shown) to cool and harden the molten solder. That is, in the operations shown in FIGS. 4A and 4B, a solder melting process by heating and a solder hardening process by cooling are performed to form each hole 1.
The solder paste 12a is changed to the solder 5. After the solder 5 is thus obtained, the screen mask 10 is peeled off from the CSP 4 as shown in FIG.
A solder projection made of solder 5 is printed on the solder ball 4c of SP4. As for the cooling of the molten solder, natural cooling may be performed without using the above-mentioned blowing means.

FIGS. 5A to 5C show CSPs after the holes 10a of the screen mask 10 are filled, respectively.
FIG. 9 is a cross-sectional view showing the behavior of the solder paste 12 until it is printed on the solder ball 4c of No. 4; The solder paste 12 filled in the hole 10a by the squeegee 11 is shown in FIG.
As shown in (a), the hole 10a is filled. In this state, when the solder fine particles inside are melted by the solder melting process, the individual solder fine particles are integrated by fusion and also integrated with the solder ball 4c. In addition, as shown in FIG. 5B, it is deformed so as to be round while contracting. The shrinkage is caused by volatilization of an internal solvent by heating, and the deformation is caused by surface tension generated when individual solder fine particles are melted and fused. As shown in FIG. 5B, the molten solder that has undergone such shrinkage and deformation significantly reduces the contact area with the inner wall of the hole. Then, when the solder is hardened and solidified by a solder hardening process by cooling, the solder 5
And almost loses its viscosity. As described above, the integration of the solder fine particles and the solder balls 4c, the reduction of the contact area,
Due to the synergistic action with the disappearance of the viscosity, the solder 5 in the hole 10a greatly reduces the frictional force with the inner wall of the hole as compared with the state of the solder paste 12, and as shown in FIG.
And is transferred and printed onto the solder ball 4c. Therefore, in this repair, unlike the case of using the conventional solder paste printing method in which the solder paste 12 in the hole 10a is transferred and printed as it is, the removability of the solder from the hole 10a is improved to improve the solder ball 4c. Insufficient printing amount of solder protrusions on the surface can be reduced.

For reference, the behavior of the solder paste 12 in the conventional solder paste printing method is shown in FIGS. 6 (a) and 6 (b).
Shown in As shown in FIG. 6 (a), in the conventional solder paste printing method, the screen mask 10 in which the holes 10a are filled with the viscous solder paste 12
By peeling from the SP4, the solder paste 12 was dragged on the inner wall of the hole, leaving a large amount of the solder paste 12 in the hole 10a. In FIG. 6A, it seems that there is a sufficient amount of solder protrusions made of the solder paste 12 printed on the solder balls 4c, but this does not cause the solder paste 12 of the solder protrusions to shrink due to heating. When this solder paste is subjected to a solder melting process and a solder hardening process, a state shown in FIG. 6B is obtained. Compared to FIG. 5 (c), it can be seen that the amount of the solder protrusion is clearly reduced.

In this repair, when the solder projection is printed on the solder ball 4c as shown in FIG.
It is desirable to use a solder paste 12 containing solder fine particles having a lower melting point than the solder balls 4c. By using such a solder paste 12, in the solder paste printing step, as shown in FIG.
This is because only the second solder fine particles can be melted, and sag due to melting of the solder balls 4c can be avoided.

By the way, the inventor of the present invention has conducted intensive research and has shown in FIG. 5B that a solid component of the solder flux of the solder paste 12 is interposed between the solder 5 and the inner wall of the hole 10a. It has been found that, in some cases, adhesion between the solder 5 and the inner wall is promoted. Even if the solid component of the solder flux is interposed in this way, it does not pose a serious problem when a relatively thin one such as the screen mask 10 of the present embodiment is used. However, when the screen mask 10 having a relatively large thickness is used, the adhesive force between the solder 5 and the inner wall due to the solid component increases due to the increase in the contact area between the solder 5 and the inner wall. There is a possibility that the amount of solder printed may be insufficient due to exceeding the fixing force with the solder 4c. Therefore, in the repair of the present embodiment, the screen mask 10 is
Before peeling off from each other, it is desirable to fill the inside of each hole 10a with an organic solvent such as isopropyl alcohol (IPA) that can melt the solid component. By filling each hole 10a with such an organic solvent, the inner wall of the hole 10a and the solder 5
Melt the solid component fixed in this organic solvent,
This is because the adhesion between the inner wall and the solder 5 due to the solid component can be released.

FIGS. 7A to 7C and FIG. 8 are explanatory diagrams showing the work flow of the mounting step. In this mounting step, first, as shown in FIG. 7A, another positioning jig 16 is placed on the positioning jig 9.
Then, the jigs are turned upside down, with the openings facing downward. Then, as shown in FIG. 7B, the CSP 4 is set on this other positioning jig 16 with the lower surface (solder ball surface) facing downward. After the CSP 4 is set on another positioning jig 16 in this way, as shown in FIG.
7 is brought up against the upper surface of the CSP 4. And
Thus, the CSP is set on the suction nozzle 17. Next, as shown in FIG. 8, on the X table 20 which slides in the left and right direction in the figure, and on the Y table 21 which slides in the depth direction in the figure, the mother substrate 1 which has been subjected to the above-mentioned removal step is completed. Is fixed. Then, an optical monitoring device 18 is interposed between the CSP 4 set on the component suction nozzle 17 and the mother board 1, and the optical monitoring device 1
8 while watching the image projected on the monitor 19 of the X.
By sliding the table 20 and the Y table 21,
Each board electrode 1a of the mother board 1 is positioned just below each solder ball 4c of the CSP 4 so as to be positioned. The optical monitoring device 18 combines the two-dimensional image of the CSP 4 on the upper side and the two-dimensional image of the mother board 1 directly below the CSP 4 so that their planar relative positions are the same as the real ones. The image is displayed on the monitor 19. After the positioning is performed while viewing the image projected in this manner, the optical monitoring device 18 is removed, the component suction nozzle 17 is slowly lowered vertically, and the CSP 4 is soft-touched to the mother substrate 1. When the vacuum function is stopped, the component suction nozzle 1 is stopped.
The CSP 4 is separated from 7 and mounted on the motherboard 1.

In this mounting step, it is desirable to apply a flux to at least one of the solder protrusion and the substrate electrode 1a by a brush, a nozzle, or the like prior to mounting (variations to be described later and the second embodiment). The same). By applying the flux in this way, the frictional force between the solder projection and the substrate electrode 1a can be increased, and the positional deviation between the two after mounting can be reduced. In addition, it is better to avoid applying the solder paste 12 instead of the flux because an undesired short circuit may occur.

After the new CSP 4 is mounted in the component removal area on the mother board 1 in this manner, a reflow process is performed to connect the board electrode 1a of the mother board 1 to the CS.
The solder ball 4c and the solder 5 interposed between the pad 4b of P4 and the solder 5 are melted and fused. Next, the molten solder is cured by performing a curing step, and the board electrode 1a of the mother board 1 and the pad 4b of the CSP 4 are connected by soldering. By this solder connection, a new CSP 4 is mounted on the component removal area of the mother board 1. The work in the reflow step is the same as the work shown in FIG. 2B, and the work in the curing step is the same as the work shown in FIG.

In the solder paste printing step of the present repair, it is desirable to use a so-called plastic mask in which the holes 10a are formed by ablation using an excimer laser or the like. In such a plastic mask, the smoothness of the inner wall of the hole is far superior to that of a metal mask having the hole 10a processed by the photolithography method or the etching method, and the removability of the solder 5 from the inside of the hole 10a is further improved. This is because it can be done.

It is desirable to use a polyimide resin as a resin material used for the plastic mask. This is because a plastic mask made of a heat-resistant polyimide resin has less deformation due to heating than a resin mask made of another resin, and can reduce defective printing positions of solder protrusions due to deformation due to heating.

Next, each modified example of the repair of the first embodiment will be described. [Modification 1] FIGS. 9A and 9B are cross-sectional views each showing a part of a work flow in the repair of Modification 1. In this repair, in the printing step, instead of melting the solder fine particles in the solder paste 12, the solder paste 12 is heated at a temperature lower than the melting point of the solder fine particles to volatilize the solvent therein. Then, due to the volatilization, at least the outer portion (hole 10a) of solder paste 12 is formed.
(A part exposed from the opening and a part in contact with the inner wall of the hole) are solidified. When the solvent is thus volatilized, the solder paste 12 slightly shrinks as shown in FIG. The screen mask 10 is contracted in this manner.
9B, the solder paste 12 can be smoothly separated from the holes 10a and transferred and printed on the solder balls 4c, as shown in FIG. 9B. Therefore, even in this repair, unlike the conventional solder paste printing method of transferring and printing the solder paste 12 in the hole 10a as it is, the removability of the solder paste 12 from the hole 10a is improved to improve the solderability. Ball 4c
Insufficient printing amount of solder protrusions on the surface can be reduced. The cause that can improve the removability of the solder paste 12 as described above is considered as follows. That is, it is considered that the solidification of at least the outer portion of the solder paste 12 reduces the adhesiveness between the outer portion and the inner wall of the hole.

Unlike the molten solder shown in FIG. 5B, the solder paste 12 in which the outer portion is solidified in the hole 10a does not fuse individual solder fine particles, and has a surface tension at the time of fusion. Does not cause a shape change. For this reason, as shown in FIG. 9B, the roundness of the tip of the solder projection after the transfer and printing is reduced as compared with that of FIG. 5B. For this reason, the contact area of the mother substrate 1 with the substrate electrode 1a increases in the subsequent mounting step. In addition, since the whole is not solidified and does not change into a complete solder, it can exhibit good elasticity.
As a result, in the reflow step and the curing step, the substrate electrode 1a is more reliably melted and cured while being in contact with the substrate electrode 1a, so that poor solder connection (defective conduction) between the substrate electrode 1a and the pad 4b can be favorably suppressed. .

FIG. 10A shows a solder ball 4c of the CSP 4.
FIG. 3 is a cross-sectional view showing a contact state between a solder protrusion made of a solder paste 12 transferred and printed on the board and a board electrode 1a of a mother board 1; As shown in the figure, the solder projections are in good contact with the substrate electrode 1a in the mounting step. On the other hand, as shown in FIG. 10B, the solder protrusion made of the solder 5 transferred and printed on the solder ball 4c in the first embodiment has a small contact area with the substrate electrode 1a due to the roundness of the tip. Become.

[Modification 2] FIGS. 11A to 11C are cross-sectional views each showing a part of a work flow in the repair of Modification 2. In this repair, the solder protrusion is CSP4
Not on the solder ball 4c, but on the electrode pattern (board electrode 1a) in the component removal area of the mother board 1. Specifically, as shown in FIG. 11A, after the screen mask 10 is brought into close contact with the component removal area of the mother board 1, the screen mask 1 is
The solder paste 12 is filled in each of the holes 10a. 4A and 4B, the solder paste 12 in each hole 10a is subjected to a solder melting process and a solder hardening process, and then the screen mask 10 is peeled from the mother substrate 1. Then, solder protrusions made of the solder 5 as shown in FIG. 11B are printed. Even in such printing, not the solder paste 12 but the solidified and modified solder 5
Is transferred and printed, it is possible to reduce the shortage of the printing amount of the solder protrusion on the substrate electrode 1a.

After printing the solder projections, FIG.
As shown in (5), after mounting the CSP 4 on the mother substrate 1, the reflow step and the curing step may be performed.

According to the experiments of the present inventors, even in the repair of the second modification, before the screen mask 10 is brought into close contact with the mother substrate 1 in the printing step, the substrate mask 1a By applying a flux beforehand, the short circuit between the electrodes caused by the oozing of the solder paste 12 could be greatly reduced. Therefore, it is desirable that the screen mask 10 be brought into close contact with the mother substrate 1 after applying a flux on the substrate electrode 1a of the mother substrate 1 in advance.

Next, a repair according to a second embodiment of the present invention will be described. Since the basic work flow in this repair is the same as the work flow in the repair of the first embodiment, only the characteristic work flow will be described here.

FIGS. 12A to 12C are cross-sectional views each showing a part of a work flow in the repair of the second embodiment. In this repair, the screen mask 10 is brought into close contact with the component removal area of the mother board 1 that has already been removed, as in the repair of the second modification.
However, the screen mask 10 does not have a frame at the end as shown in FIG. 11A, but uses a sheet-like mask without such a frame. And
Each hole 10a of the screen mask 10 is filled with a solder paste 12 using a squeegee or the like (filling step). Next, as shown in FIG. 12B, the CSP 4 is mounted on the screen mask 10 so that the tip of each ball electrode 4c of the CSP 4 is inserted into the corresponding hole 10a (mounting step). Then, by performing the melting step and the curing step, each ball electrode 4c and each substrate electrode 1a are connected by soldering, and as shown in FIG. 12C, the screen mask 10 is brought into a so-called killing state.

In such a repair, the screen mask 10 and the mother substrate 1 are not separated from each other, and the entire amount of the solder fine particles in the solder paste 12 filled in each hole 10a of the screen mask 10 is removed from the substrate electrode of the mother substrate 1. 1a and CS
P4 contributes to the solder connection with the solder ball 4c.
For this reason, it is possible to eliminate a poor solder connection between the board electrode 1a and the pad 4b caused by the insufficient printed amount of the solder protrusion. It should be noted that the CSP 4 does not have a protruding electrode composed of the pad 4b and the solder ball 4c, as in the CSP 4.
To repair an LGA having only
The solder protrusion may be printed on the pad 4b in advance by the solder paste printing process described in the embodiment.

FIGS. 13A and 13B respectively show the second
It is a sectional view showing a part of work flow in repair of a modification of an embodiment. In this repair, as shown in FIG. 13A, by using a screen mask 10 provided with a horizontally long hole facing a plurality of substrate electrodes 1a, as shown in FIG. A plurality of substrate electrodes 1a can be short-circuited. Then, the electrode pattern of the mother substrate 1 can be changed by the short circuit. In this repair, if a metal lead member as shown in each drawing of FIG. 12 is put into the hole 10a prior to the filling step, the plurality of substrate electrodes 1a can be more reliably short-circuited. Can be.

In the repair of this modified example, a screen mask 10 having a size larger than the component removal area of the mother substrate 1 is used, and the substrate electrode 1a around the CSP 4 is short-circuited, not the substrate electrode 1a immediately below the CSP 4. For this purpose, the screen mask 10 may be provided with a dedicated hole 10a.

Also in the repair of this modification, it is desirable to apply a flux on the substrate electrode 1a of the mother substrate 1 before the screen mask 10 is brought into close contact with the mother substrate 1 in the printing step. .

As described above, in each of the embodiments and modified examples, C
The repair to replace SP4 was explained, but BGA,
Needless to say, the present invention can be applied to repair for removing / mounting other electronic components such as LGA, QFP, LSI, and bare chip.

Although the repair using a screen mask in the printing process has been described, the present invention can be applied to a repair in which a printing process in which an intaglio in which each recess is filled with a solder paste is closely attached to a mother board or an electronic component is performed. It is.

[0062]

According to the first, second, third or fourth aspect of the present invention, the shortage of the printed amount of the solder projection on the substrate or the electronic component is reduced. There is an excellent effect that it is possible to reduce poor conduction with the substrate.

In particular, according to the second or fourth aspect of the present invention, the solder particles are melted and hardened while the solder projections are brought into contact with the substrate or the electronic component more reliably than the first or third aspect of the present invention. There is an excellent effect that conduction failure with an electronic component can be more reliably reduced.

According to the fifth aspect of the present invention, there is an excellent effect that a poor conduction between the substrate and the electronic component caused by a shortage of the printed amount of the solder protrusion can be eliminated.

According to the sixth aspect of the present invention, even in the case of an electronic component having a flat electrode instead of a protruding electrode, the flat electrode and the electrode pattern of the substrate are soldered to mount the electronic component on the substrate. There is an excellent effect that can be.

According to the seventh aspect of the invention, there is an excellent effect that a new conduction defect caused by the sixth aspect of the invention can be reduced.

According to the eighth aspect of the present invention, it is possible to change the electrode pattern by short-circuiting any electrodes in the substrate electrode pattern while avoiding undesired short-circuiting of the bonding electrode of the electronic component. Has an excellent effect.

According to the ninth aspect of the present invention, the shortage of the printing amount of the solder projection is reduced as compared with the case where the stencil or the intaglio processed by the photolithography method or the etching method is used. There is an excellent effect that conduction failure between the substrate and the electronic component can be more reliably reduced.

According to the tenth aspect of the present invention, there is an excellent effect that the printing position defect of the solder projection caused by the deformation of the stencil or the intaglio caused by the heating can be reduced.

[Brief description of the drawings]

FIG. 1 is an exemplary perspective view showing a mother board to be repaired according to a first embodiment;

FIGS. 2 (a) to 2 (c) are explanatory diagrams showing work flows of a step of removing the repair.

FIGS. 3A to 3C are explanatory diagrams showing work flows of a solder paste printing step of the same repair, respectively.

FIGS. 4A to 4C are explanatory diagrams each showing a continuation of the same work flow.

5 (a) to 5 (c) are cross-sectional views showing the behavior of the solder paste from the time of filling the holes of the screen mask to the time of printing on the solder balls of the CSP in the same repair.

FIGS. 6A and 6B are cross-sectional views showing the behavior of a solder paste in a conventional solder paste printing method.

FIGS. 7A to 7C are explanatory diagrams each showing a work flow of a mounting step of the repair.

FIG. 8 is an explanatory diagram showing a continuation of the work flow.

FIGS. 9A and 9B are cross-sectional views each showing a part of a work flow in a repair of Modification Example 1. FIGS.

FIG. 10A is a sectional view showing a contact state between a solder projection and a substrate electrode in the repair. FIG. 3B is a cross-sectional view illustrating a contact state between the solder protrusion and the substrate electrode in the repair according to the first embodiment.

FIGS. 11A to 11C are cross-sectional views each showing a part of a work flow in a repair of Modification Example 2. FIGS.

FIGS. 12A to 12C are cross-sectional views each showing a part of a work flow in a repair of the second embodiment.

FIGS. 13A and 13B are cross-sectional views each showing a part of a work flow in a repair according to a modification of the second embodiment.

[Explanation of symbols]

 Reference Signs List 1 mother board 1a substrate electrode 2 bare chip 3 QFP 4 CSP 4a package 4b pad 4c solder ball 5 solder 6 stage 7 hot air nozzle 8 hot air 9 positioning jig 10 screen mask 11 squeegee 12 solder paste 12a solder paste (solidified) 15 blowing air 16 positioning Jig 17 Component suction nozzle 18 Optical monitoring device 19 Monitor 20 X table 21 Y table

Claims (10)

[Claims] A removing step of removing a mounted electronic component from a board, a printing step of printing solder projections on an electrode pattern in a component removing area of the board, and connecting the electronic component or another electronic component to a bonding electrode thereof. And a mounting step of mounting on the substrate such that the solder projections overlap with each other, a melting step of melting the solder in the solder projections by heating, and curing the melted solder by cooling to form the electrode pattern. In the method for repairing an electronic circuit board, a curing step of performing solder connection with the bonding electrode is performed, in the printing step, a solder melting process by heating and a solder curing process by cooling the solder paste in the stencil or intaglio. A method of repairing an electronic circuit board, comprising: removing the stencil or intaglio that has been brought into close contact with the substrate, and printing the solder protrusions. 2. The method for repairing an electronic circuit board according to claim 1, wherein in the printing step, the solder particles of the solder paste in the stencil or intaglio are not melted, and the solder paste is heated to a temperature lower than the melting point of the solder particles. And evaporating the solvent in the solder paste by heating in step (b). 3. A removing step of removing a mounted electronic component from a substrate, and a printing step of printing solder projections on a bonding electrode of the electronic component or another electronic component by a solder paste printing method using a stencil or an intaglio. And a mounting step of mounting the electronic component after the printing step in a component removal area of the board so that the solder protrusion and the electrode pattern of the board overlap,
In a method of repairing an electronic circuit board, a melting step of melting the solder in the solder protrusions by heating, and a curing step of hardening the melted solder by cooling and solder-connecting the electrode pattern and the joining electrode are performed. In the printing step, the solder paste in the stencil or intaglio is subjected to a solder melting process by heating and a solder hardening process by cooling, and then the stencil or intaglio that has been brought into close contact with the electronic component is replaced by the electronic component. A method for repairing an electronic circuit board, wherein the method is performed by printing the solder projections by peeling off the solder projections. 4. The method for repairing an electronic circuit board according to claim 3, wherein in the printing step, the solder particles of the solder paste in the stencil or intaglio are not melted, and the solder paste is heated to a temperature lower than the melting point of the solder particles. And evaporating the solvent in the solder paste by heating in step (b). 5. A method for repairing an electronic circuit board, comprising the steps of: removing a mounted electronic component from a substrate; and mounting the electronic component or another electronic component in a component removal area of the substrate. An electronic component having a plurality of projecting electrodes projecting from the lower surface as bonding electrodes is mounted on the substrate, and in the mounting step, each of the holes of the stencil is aligned with a corresponding position on the electrode pattern of the substrate. A sealing step of bringing the stencil into close contact with the substrate, a filling step of filling each hole of the stencil with the solder paste, and placing an electronic component on the component removal area and tipping each protruding electrode. A mounting step of inserting the solder paste in the corresponding holes of the stencil; a melting step of heating the solder paste in each hole to melt the solder particles in the solder paste; and cooling the melted solder. Electronic circuit board repair method which is characterized in that cured implementing a curing step of soldering connection between the electrode pattern and the protrusion electrodes me. 6. The method for repairing an electronic circuit board according to claim 5, wherein an electronic component having a plurality of flat electrodes provided on the lower surface of the main body instead of the projecting electrodes as the bonding electrodes is mounted, and A method of printing solder projections on each flat electrode by a solder paste printing method using a stencil or an intaglio, prior to the electronic circuit board repairing method. 7. The method for repairing an electronic circuit board according to claim 6, wherein, in the printing step, a solder melting process by heating and a solder hardening process by cooling are performed on the solder paste in the stencil or intaglio that is in close contact with the electronic component. After giving or
Heating the solder paste at a temperature lower than the melting point of the solder particles to volatilize the solvent in the solder paste, and peeling off the stencil or intaglio from the electronic component to print the solder protrusions. To repair electronic circuit boards. 8. The method for repairing an electronic circuit board according to claim 5, 6 or 7, wherein said stencil used in said contacting step faces two or more independent electrodes of said electrode pattern. Wherein the solder particles in the solder paste filled in the holes are cured so as to short-circuit the electrodes in the curing step. 9. The method of claim 1, 2, 3, 4, 5, 6, 7 or 8.
The method for repairing an electronic circuit board according to the above, wherein a stencil or an intaglio used in the printing step is made of resin in which holes or recesses are ablated in a resin material. 10. The method of repairing an electronic circuit board according to claim 9, wherein a polyimide resin is used as said resin material.