JP2001156441A - Method for repairing csp/bga - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which no unsoldered part is produced during remounting CSP/BGA. SOLUTION: This method includes a step (d) for supplying a highly active flux 5 to the inside of a dam block 4 and heating it with a heater 6 provided under a wiring board 1; a step (e) for removing the dam block 4, cleaning and removing the remaining flux 5, applying a low active flux to the area of the wiring board 1 where a BGA (or CSP) is remounted, and remounting a non- defective BGA (or CSP) 2b; and a step (f) for bonding the wiring board 1 and non-defective BGA (or CSP) 2b by reflow.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of repairing a CSP / BGA, and more particularly, to a method of manufacturing an electronic circuit device, the method of mounting a defective semiconductor device when the semiconductor device once mounted is defective. CSP that removes from the substrate and mounts a new semiconductor device on the semiconductor device mounting substrate again
・ Related to BGA repair method.

[0002]

2. Description of the Related Art In this type of repair method, when a defective semiconductor device (electronic component) is removed from a wiring board (substrate for mounting a semiconductor device), a connection portion on the wiring board, that is, a land, is, for example, a metal brazing. Solder residue remains.
Since the height of the solder residue is not uniform, if a new semiconductor device is mounted again in this state, a connection failure is caused, which causes disconnection and the like. Therefore, the following steps (1) and (2) have been performed to prevent poor connection.

(1) First, a metal plate that is wetted by solder is pressed against the solder residue, the metal plate is heated in this state, and the solder residue is collected on the metal plate side, thereby completely removing the solder residue on the wiring board. Remove.

(2) In remounting, the solder bump electrode itself of a new semiconductor device is melted by heating and can be connected to a wiring board, so that flux is applied to the land to prevent oxidation. Then, the solder bump electrodes are heated and melted to connect them. In addition, heating and
For melting, an atmosphere furnace was used, or heated air was applied to the solder bump electrodes.

By the way, when an electronic component is flip-chip mounted on a circuit board using a solder bump electrode, if there is a difference in the coefficient of thermal expansion between the semiconductor device and the wiring board, the temperature at which the solder bump electrode is heated and melted is reduced. Due to a difference in expansion and contraction between the semiconductor device and the wiring board caused by a temperature difference from room temperature or a temperature difference between an operating state of the semiconductor device and a temperature in a stopped (preserved) state, that is, a thermal projection stress, There is a possibility that distortion is generated in the portion and a connection failure is induced. Therefore, the distortion resulting from the difference in the coefficient of thermal expansion has reduced the reliability of the product.

However, in the above-mentioned conventional repair method, since the solder residue is completely removed and the connection is made only by the solder amount of the solder electrode itself, the solder amount is small. For this reason, the height Hj of the connection cannot be increased, and it has been difficult to improve the reliability of the product.

A conventional CSP / BGA repair method will be described in detail with reference to the drawings.

FIG. 2 is a flowchart showing a first conventional example.
(See, for example, JP-A-10-163624)
First, in step S101, when it is confirmed that the semiconductor device on the wiring board is defective, in step S102, the defective semiconductor device is heated with a lamp to melt the solder bump electrodes, thereby removing the semiconductor from the wiring board. Remove the device.

Next, in step S103, after removing the defective semiconductor device, a uniform amount of solder residue remaining on the wiring board is left, and excess solder is removed.

Next, in step S104, a new semiconductor device is prepared, and a solder paste is supplied to the tip of the solder bump electrode of the new semiconductor device by a transfer method to prepare for remounting (step S105). .

Next, in step S106, a new semiconductor device to which the solder paste has been transferred is aligned with a wiring board on which a uniform amount of solder residue remains.

Next, in step S107, the remounted semiconductor device is heated by the light of a lamp to melt the solder bump electrode and the solder paste, and connect the two, thereby completing the repair process (step S108).

Here, a near-infrared lamp (IR lamp) is preferable as the lamp for the following reasons. That is, in a semiconductor device, Si is mainly used as a material of a circuit board, and Si is in a near infrared region (1 μm to 5 μm in wavelength).
μm) is well transmitted, and if light of that wavelength is used, the solder bump electrode and the solder paste can be efficiently heated directly through the Si.

According to this technique, a solder residue is left in a uniform amount corresponding to the surface tension of the solder, and a method of supplying a solder paste to a new semiconductor device is adopted. Also, a sufficient amount of solder can be secured. For this reason, as can be seen from the Coffin-Manson connection fatigue life equation, the height Hj of the connection portion can be increased and the maximum strain γmax at the connection portion can be reduced, so that poor connection, that is, disconnection does not occur. Therefore, the reliability of the semiconductor device can be improved.

Next, a technique for repairing a flip-chip type semiconductor device employing a gold bump which cannot be repaired because re-solder cannot be supplied and has been discarded will be described.
If the connection bump between the LSI chip and the wiring board is gold,
The repair method has not been established because it is difficult to supply the solder again to the substrate after removing the LSI chip. That is, after the removal of the LSI chip, the molten and wet state of the solder is different at each of the bump bonding portions. Therefore, when the solder is removed at the spots, the solder remains unevenly on the mounting pads of the wiring board, and the solder is re-used. Supply was difficult.

Here, in the initial mounting of an LSI chip in which gold is used for the connection bump, generally, solder is previously applied to the LSI mounting pad of the wiring board, and the solder is connected to the gold bump of the LSI chip. Do it. As a method of supplying the solder to the board side, there are a Super Jafit method of Showa Denko KK and a super solder method of Furukawa Denko KK. LS
It is not suitable for re-solder supply when replacing an I chip.

FIGS. 3A to 3F are side views showing a second conventional example in the order of steps. (For example, Japanese Patent Application Laid-Open No. 10-0
No. 22340).

After the LSI chip is mounted on the wiring board 205, it is completely adhered with a sealing resin 206 as shown in FIG. 3B. Before that, an electrical operation check is performed to determine whether the LSI is good or bad. Is usually determined. Now, it is assumed that as a result of this determination, the LSI chip 202 in FIG. 3A is defective.

First, a method of removing the defective LSI chip 202 will be described. As shown in FIG. 3A, after the LSI adsorption and heating means 201 is adsorbed on the defective LSI chip 202,
Heating the defective LSI chip 202 to melt the solder,
The defective LSI 202 is peeled off from the wiring substrate 205. L
The SI adsorption heating means 201 has a heating and pressurizing mechanism and an LSI chip suction mechanism. At this time, the bonding portion 2 between the defective LSI 202 and the wiring board 205
04 defective nitrogen chip 20 while blowing nitrogen gas
2 is peeled off from the wiring board. The defective LSI chip 202 is removed by sucking and holding the defective LSI chip 202.
This is performed by operating the SI adsorption heating means 201.

According to this, after the LSI chip 202 is removed, the variation of the solder remaining on the LSI mounting pad 211 is suppressed, and the step of smoothing the surface of the LSI mounting pad 211 for reattaching the chip is omitted. And the repair process can be simplified.

As the sealing resin 206, an epoxy sealing resin is used. Heating of the defective LSI chip 202 by the LSI adsorption and heating means 201 is 250 to 300 [° C.], and nitrogen gas is blown under the condition that the oxygen concentration is 500 ppm or less.

Next, a method of mounting the alternative LSI chip will be described. FIG. 3B shows a state after the defective LSI chip 202 is removed. On the wiring board 205, a set of LS
The pad 211 for I mounting is left. In this state, first, the flux 21 is applied to the LSI mounting pad 211.
3 is applied in layers. Subsequently, the layered solder film 208 spread on the surface of the die 207 is
With the punch 2
09 is used to punch out the solder film 208. As a result, the punched layered solder disk 210 is
The solder is supplied to the upper layer of the mounting pad 211 (hereinafter, this solder supply method is referred to as a micro press method). The solder disk 210 is bonded to the LSI mounting pad 211 by a flux 213 applied to the LSI mounting pad 211 in advance.
(FIG. 3D).

Subsequently, as shown in FIG.
The SI chip 212 is adsorbed by the LSI adsorption / heating means 201, and alignment is performed above the LSI mounting pad 211. Then, after heating the LSI adsorption and heating means 201 to a predetermined temperature to raise the temperature of the new LSI chip 212, the wiring board 205 is pressed to melt the solder disk 210. As a result, the new LSI chip 212 and LSI
The mounting pad 211 is bonded. Then, FIG.
As shown in FIG.

According to this, even when there are already mounted components around the chip re-attachment position, the solder disk 210 is placed at a desired position corresponding to the LSI mounting pad 211.
And repair work can be facilitated.

Since it is desirable that the flux 213 has relatively high tackiness, the Deltalux 5 made by Senju Metal Co., Ltd.
27-7, and 50 [μ]
m] using a thick tin-silver solder and punching it out to a diameter of 80
[Μm] tin-silver solder disk 210 is formed. LS
The heating of the I-adsorption pressurizing means 201 was performed at 250 to 300 ° C. The LSI chip 212 has a wiring board 205 of 0.5 k
Pressurize with g. At this time, nitrogen gas is blown into the gap between the LSI chip 212 and the wiring substrate 205 to reduce the oxygen concentration to 5%.
The content is set to 00 ppm or less.

FIGS. 4A to 4F are side sectional views showing a third conventional example in the order of steps. BGA (or CSP)
When repairing the wiring board 1 as shown in FIG.
In order to remove the oxide film 3 on the solder surface on the side, a highly active flux 4 is applied thinly, and the CSP / BGA 2 is mounted again. Then, as shown in FIG. Had gone.

However, when the number of repairs increases and the oxidation of the solder surface progresses, this method cannot sufficiently remove the oxidation of the solder surface, and as a result, the unsoldered portion 8 as shown in FIG. Problem had occurred. When the amount of the high-active flux 5 applied is increased as shown in FIG. 4 (e) in order to improve this problem, the oxide film is removed and the unsoldered portion 8 disappears.
As shown in (f), the washing after the reflow resulted in a high active flux residue 9, which was a problem in reliability. The high active flux residue 9 was remarkably generated due to the increase in the number of pins and the narrow pitch accompanying the high integration.

[0028]

SUMMARY OF THE INVENTION The above-mentioned conventional CSP
-The BGA repair method has the disadvantage that when the number of repairs increases and the oxidation of the solder surface progresses, the oxidation of the solder surface cannot be sufficiently removed, so that when the CSP / BGA is remounted, unsoldered portions are generated. there were.

[0029]

Means for Solving the Problems CSP · B of the first invention
The GA repair method includes a step of removing a defective BGA (or CSP) from a wiring board, and a step of removing the BGA (or CSP).
The step of forming a bank around the area of the wiring board for reloading, the step of supplying a highly active flux to the inside of the bank and heating it with a heater installed at the bottom of the wiring board, and the step of removing the bank , Cleaning residual high activity flux
Removing, applying a low-activity flux to the area of the wiring board on which the BGA (or CSP) is to be remounted, and reloading a good BGA (or CSP); and reflowing the wiring board and the good BGA (or CSP). ) Is joined.

In a CSP / BGA repair method according to a second aspect, in the first aspect, the shape of the bank is rectangular.

According to a third aspect of the invention, in the CSP / BGA repair method according to the first aspect, the bank has a polygonal shape.

In a CSP / BGA repair method according to a fourth aspect, in the first aspect, the shape of the bank is circular.

According to a CSP / BGA repair method of a fifth invention, in the first invention, the material of the bank is an epoxy resin.

According to a sixth aspect of the present invention, there is provided the CSP / BGA repair method according to the first aspect, wherein
Exceeds the height of the solder (bump) attached to the land.

The repair method for CSP / BGA of the seventh invention is the synthetic resin frame in which the main material of the bank is injection-molded in the first invention.

In a CSP / BGA repair method according to an eighth aspect, in the first aspect, the bank is formed by applying an epoxy resin to the wiring board with a brush or a syringe.

In a CSP / BGA repair method according to a ninth aspect, in the first aspect, the bank is removed, and an organic solvent such as methyl ethyl ketone is used to wash and remove the remaining high-activity flux.

[0038]

Next, the present invention will be described in detail with reference to the drawings.

1A to 1F are side sectional views showing an embodiment of the present invention in the order of steps. The CSP / BGA repair method shown in FIGS. 1A to 1F is a step of removing a defective BGA (or CSP) 2 a from the wiring board 1 (FIG. 1).
(B)) and a step of forming a bank 4 around the area of the wiring board 1 on which the BGA (or CSP) is to be remounted (FIG. 1)
(C)), a step of supplying the highly active flux 5 to the inside of the bank 4 and heating the flux by a heater 6 installed at the lower part of the wiring board 1 (FIG. 1D), and removing the bank 4 Then, the remaining high-activity flux 5 is washed and removed, and the low-activity flux 7 is applied to the region of the wiring board 1 on which the BGA (or CSP) is to be mounted again, and a good BGA (or CSP) 2b
(FIG. 1 (e)), and a step (FIG. 1 (f)) of reflowing and joining the wiring board 1 and a non-defective BGA (or CSP) 2b.

The shape of the bank 4 is rectangular, polygonal or circular, and its material is, for example, epoxy or the like, and its height exceeds the height of the solder (bump) attached to the land of the wiring board 1. Just do it.

To form the bank 4, a rectangular, polygonal or circular synthetic resin frame is adhered to the wiring board 1,
Alternatively, an epoxy resin may be applied to the wiring board 1 with a brush or a syringe.

The bank 4 is removed, and the remaining high-activity flux 5 is washed and removed by using an organic solvent such as methyl ethyl ketone.

Next, the operation will be described. First, as shown in FIG. 1B, the CSP / BGA 2 to be repaired is removed. Next, as shown in FIG. 1C, a bank 4 for preventing the high-active flux 5 from flowing out along the outer periphery of the solder bump area of the wiring board 1 is formed of epoxy or the like. Next, as shown in FIG. 1D, the bank 4 formed in (c) above is used.
Is supplied with a high active flux 5 in an amount sufficient to immerse the solder on the wiring board 1 side, and heated by a heater 6 to remove the oxide film 3 on the solder surface.

Next, as shown in FIG. 1 (e), the high-activity flux 5 and the bank 4 are washed and removed with an organic solvent such as methyl ethyl ketone, and the low-activity flux 7 is applied thinly, and then the CSP / BGA 2 is removed. Reload and finally Figure 1
As shown in (f), reflow is performed to complete the repair work. Since the low activity flux 7 used last has low activity, there is no problem in reliability even if it is not removed after reflow.

[0045]

According to the CSP / BGA repair method of the present invention, the removal of the oxide film from the solder surface on the wiring board side by the high-active flux and the high-active flux cleaning step are performed by the CSP / B.
By performing the process before mounting the GA, defects such as unsoldering and high active flux remaining can be prevented, and there is an effect that a highly reliable high-density mounting repair work can be performed.

[Brief description of the drawings]

FIGS. 1A to 1F are side sectional views showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a first conventional example.

FIGS. 3A to 3F are side views showing a second conventional example in the order of steps.

FIGS. 4A to 4F are side sectional views showing a third conventional example in the order of steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring board 2b BGA 3 Oxide film on solder surface 4 Embankment 5 High active flux 6 Heater 7 Low active flux 8 Non-solder part 9 High active flux remaining

Claims (9)

[Claims] 1. A step of removing a defective BGA (or CSP) from a wiring board; a step of forming a bank around a region of the wiring board on which the BGA (or CSP) is to be mounted; and a high active flux inside the bank. And heating it with a heater installed at the bottom of the wiring board, removing the bank, washing and removing the remaining high-activity flux, and re-mounting the BGA (or CSP) on the wiring board. A process of applying a low-activity flux to the substrate and re-mounting a good BGA (or CSP); and reflowing the wiring board and a good BGA (or CSP).
And a step of joining the CSP and the BG
A repair method. 2. The CSP / BGA repair method according to claim 1, wherein the shape of the bank is rectangular. 3. The bank according to claim 1, wherein said bank has a polygonal shape.
CSP / BGA repair method described. 4. The CSP / BGA repair method according to claim 1, wherein the shape of the bank is circular. 5. The CSP / BGA repair method according to claim 1, wherein the material of the bank is an epoxy resin. 6. The height of the bank exceeds a height of solder (bump) attached to a land of the wiring board 1.
CSP / BGA repair method described. 7. The CSP / BGA repair method according to claim 1, wherein the main material of the bank is an injection-molded synthetic resin frame. 8. The wiring board is formed by applying epoxy resin to the wiring board with a brush or a syringe.
CSP / BGA repair method described. 9. The CSP / BGA repair method according to claim 1, wherein the bank is removed and an organic solvent such as methyl ethyl ketone is used to wash and remove the remaining highly active flux.