JPH05190553A - Mounting structure of semiconductor component and manufacture of its solder bump - Google Patents

Abstract

PURPOSE:To provide the mounting structure for a PGA type semiconductor component and a method of manufacturing solder bumps which are used at mounting, where an aligning operation is easily carried out in the mounting structure concerned and the solder bumps of composite structure are composed of high melting point solder bumps and low melting point, solder bumps. CONSTITUTION:In a semiconductor device where a PGA type semiconductor element 5 is surface-mounted on a circuit board by reflow soldering, high melting point solder bumps 20 are formed on general pads 2-2 arranged on a circuit board 1 corresponding to the general pins 6-2 of the PGA type semiconductor element 5 and also on selected pads 2-1 arranged corresponding to selected pins 6-1 arranged on the periphery of the PGA type semiconductor element 5 and low melting point solder bumps 21 are formed on the tops of the high melting point solder bumps 20 arranged on the periphery of the PGA type semiconductor element 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a mounting structure of an A (Pin Grid Array Package) type semiconductor component and a method of manufacturing solder bumps used at the time of mounting.

With the increase in the number of pins of semiconductor parts, in recent years, a large number (about 500 pins) of pins (close to a pin pitch of about 0.9 mm) are planted in a matrix on the bottom surface of the package.
A type semiconductor components are provided.

In such a PGA type semiconductor component, it is general that each pin is reflow-soldered to be connected to a corresponding pad and surface-mounted on a circuit board. On this occasion,
Since it is inefficient to check the displacement of all the pins and pads, it is necessary to select a certain number of pins from the power supply pin, the ground pin, or the signal pin, and use optical means or electrical characteristics. The measuring means inspects the displacement between the pin and the pad.

[0004]

2. Description of the Related Art FIGS. 4A and 4B are views of a conventional example, in which FIG. 4A is a sectional view after surface mounting, and FIG.

In FIG. 4, reference numeral 5 denotes a PGA type semiconductor component in which electrodes 7 are provided in a zigzag lattice pattern on the lower surface of the package, and pins 6 are silver-brazed to the respective electrodes 7 so as to stand upright.

The PGA type semiconductor component 5 as described above is surface-mounted on the circuit board 1 by reflow soldering (solder 8) the respective pins 6 to the corresponding pads 2.
By the way, providing a solder layer for reflow by a screen printing method or the like on the pads 2 arranged at a fine pitch such as a pitch of 0.9 mm is because the size of the cream-like solder applied and formed on the pad 2 varies and Insulation failure may occur between adjacent pads due to the outflow from the above pads.

Therefore, conventionally, as shown in FIG. 4B, a solder bump 10 is provided on each pad 2,
The PGA type semiconductor component 5 is mounted on the circuit board 1 by heating the solder bumps 10 and performing reflow soldering.

[0008]

By the way, the PGA type semiconductor component surface-mounted on the circuit board by reflow soldering is subjected to the positional deviation inspection between the pin and the pad as described above. At this time, if misalignment is detected, hot air is blown into the lower part of the package from the periphery of the PGA type semiconductor component to heat the solder connecting the pads and the pins to a reflow state, and the position of the PGA type semiconductor component is changed. After adjustment, the pins and pads are aligned again, and then the molten solder is cured to remount the PGA type semiconductor component.

However, since it is difficult to blow hot air into the narrow gap between the package of the PGA type semiconductor component and the circuit board, the solder for soldering the pins arranged in the center of the package is difficult to melt. For this reason, it is difficult to shift the position of the PGA type semiconductor component in the correct direction,
There is a problem in that it is not possible to carry out a satisfactory alignment.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a mounting structure of a semiconductor component which can be easily aligned. Another object is to provide a method for manufacturing a solder bump having a composite structure including a high melting point solder bump and a low melting point solder bump.

[0011]

In order to achieve the above-mentioned object, the present invention, as illustrated in FIG. 1, is an apparatus for surface-mounting a PGA type semiconductor component on a circuit board by reflow soldering. The high-melting-point solder bumps 20 are formed on the general pads 2-2 for soldering the general pins 6-2 of the PGA-type semiconductor components 5 arranged on the circuit board 1 and arranged on the circuit board 1. Perimeter selected pin 6-1
A high-melting-point solder bump 20 is formed on the selected pad 2-1 to be soldered, and a low-melting-point solder bump 21 is further formed on the high-melting-point solder bump 20.

Further, as shown in FIG. 3, the manufacturing method is a first heat resistant resin having a window on the surface of the circuit board 1 above the selected pad 2-1 and general pad 2-2. After providing the resist film 31 of, the high melting point cream solder 25 is applied to the surfaces of the selected pad 2-1 and general pad 2-2, and the high melting point cream solder 25 is heated to a predetermined temperature, respectively. Solder is deposited on the selected pad 2-1 and general pad 2-2, respectively, to provide the high melting point solder bump 20.

Next, a second resist film 32 made of a heat-resistant resin having a window above the high melting point solder bumps 20 of the selected pad 2-1 is provided on the circuit board 1 and the selected pad 2-
The low melting point cream solder 26 is applied to the surface of the high melting point solder bump 20 of 1 and the low melting point cream solder 26 is heated to a predetermined temperature, and the high melting point solder bump 20 of each selected pad 2-1 is applied. Solder is deposited on top of this to form low-melting-point solder bumps 21 in an overlapping manner.

After that, the second resist film 32 and the first resist film 31 are etched and removed.

[0015]

In the present invention, as shown in FIG. 2A, the low melting point solder bumps 21 are heated to the melting temperature to reflow only the low melting point solder bumps 21 and the selected pins 6-1 and Only the selected pad 2-1 is reflow-soldered with the low melting point solder 21A to temporarily mount the PGA type semiconductor component 5 on the circuit board 1. And this selected pin 6-1 and selected pad 2-1
Check the positional deviation between and.

At this time, if a misalignment is detected,
The low melting point solder 21A is melted by hot air, but the selected pins 6-1 are arranged on the outer peripheral portion of the PGA type semiconductor component 5, so that the reflow state can be easily achieved.

When the positional deviation adjustment is completed, the high melting point solder bumps 20 are heated to the melting temperature to reflow the high melting point solder bumps 20 and, as shown in FIG. Solder the selected pad 2-1 and the selected pin 6-1 and the other general pad 2-2 and the general pin 6-2 with high melting point solder 20
Reflow soldering shall be done at A. By doing so, the alignment work is easily performed.

Further, according to the above-described solder bump manufacturing method, the low melting point solder bump can be superimposed on the high melting point solder bump of the selected pad, and only the high melting point solder bump can be used for the other general pads. Can be formed.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to FIGS. The same reference numerals denote the same objects throughout the drawings.

FIG. 1 is a diagram of an embodiment of the present invention. (A) is a sectional view of a main part, (B) is a plan view of a circuit board, and (A) and (B) of FIG. 2 show the operation of the present invention. 3A and 3B are cross-sectional views showing the manufacturing process of the present invention.

As shown in FIG. 1A, in the PGA type semiconductor component 5, electrodes 7 are provided in a zigzag lattice on the lower surface of the package, and pins are silver-soldered on each electrode 7 to be planted. It is arranged.

Among the arranged pins, a pin 6-1 selected by selecting a specific number of pins from the power supply pin, the ground pin, and the signal pin arranged on the outer peripheral portion is used as an optical means or an electrical characteristic measuring means. By this selected pin
Perform a misalignment check between 6-1 and the corresponding pad and if these selected pins 6-1 are not misaligned,
It is determined that the other general pins 6-2 are also aligned.

On the other hand, among the pads arranged in a zigzag grid pattern on the surface of the circuit board 1, the pads for reflow soldering the selected pins 6-1 are selected by hatching in FIG. 1 (B). Pad 2-1.

Then, as shown in FIG. 1A, a high melting point solder bump (melting point 270 ° C. to 280 ° C.) 20 is formed on the selected pad 2-1 and other general pad 2-2. ing.
In addition, only the selected pad 2-1 has a low melting point solder bump (melting point 230 ° C to 240 ° C) above the high melting point solder bump 20.
21) is formed.

In order to mount the PGA type semiconductor component 5 on the circuit board 1 provided with the solder bumps as described above, first the respective pins are aligned with the corresponding pads, and the PGA is arranged.
Type semiconductor component 5 is placed on the circuit board 1, and low melting point solder bumps
The circuit board 1 is heated to a melting temperature of 21.

As a result, the low melting point solder bump 21 of the selected pad 2-1 is reflowed, and the selected pin 6-1 and the selected pad 2-1 are separated as shown in FIG. 2 (A). ,
Solder with low melting point solder 21A.

Then, the inspection of the positional deviation between the selected pin 6-1 and the selected pad 2-1 is carried out. If misalignment is detected at this time, the low melting point solder 21A
The selected pin 6-1 will melt the PGA.
Since they are arranged on the outer peripheral portion of the mold semiconductor component 5, they are easily heated and brought into a reflow state. Therefore, the displacement can be adjusted.

Next, when the positional deviation adjustment is completed, the circuit board 1 is heated to the melting temperature of the high melting point solder bump 20. This causes the high melting point solder bumps 20 to reflow, as shown in FIG.
The selected pin 6-1, the other general pad 2-2 and the general pin 6-2 are soldered with the high melting point solder 20A.

A method of manufacturing the solder bump having the double structure will be described below. As shown in FIG. 3A, a heat-resistant resin such as polyimide resin is applied to the surface of the circuit board 1 and cured, and then the selected pad 2-1 and general pad 2-by photolithography means. A first resist film 31 having a window on the upper side of 2 is deposited on the surface of the circuit board 1.

Next, as shown in FIG. 3B, a high melting point for precipitation is formed on the entire surface of the first resist film 31 including the upper surfaces of the selected pad 2-1 and general pad 2-2. Apply creamy solder 25.

Then, the high melting point creamy solder 25 is heated to a predetermined temperature (melting temperature of the high melting point solder + 30 ° C.) to advance the solder deposition reaction. Then, the circuit board 1 is washed to remove the unreacted high melting point cream-like solder 25, and then, as shown in FIG.
As shown in FIG. 2, the high melting point solder bump 20 having a substantially rectangular cross section is provided on the surfaces of the selected pad 2-1 and the other general pad 2-2.

Next, after a heat resistant resin such as a polyimide resin is applied and cured on the high melting point solder bumps 20 and the first resist film 31, by photolithography means.
As shown in FIG. 3D, the second resist film 32 having a window above the selected pad 2-1, that is, the upper surface of the high melting point solder bump 20 of the selected pad 2-1 is opened. Are formed.

Then, as shown in FIG. 3E, the surface of the second resist film 32 including the upper surface of the high-melting-point solder bump 20 on the selected pad 2-1 is entirely deposited on the surface of the second resist film 32. Apply the low melting point cream solder 26 and apply the low melting point cream solder 26.
Is heated to a predetermined temperature (melting temperature of low melting point solder + 30 ° C.) to promote a solder deposition reaction, and the cross section is almost rectangular at the upper part of the high melting point solder bump 20 provided on the selected pad 2-1. Low-melting-point solder bumps 21 having a shape are provided so as to overlap each other.

Then, as shown in FIG. 3F, the circuit board 1 is washed to remove the unreacted low melting point cream solder 26, and then etched to etch the second resist film 32 and the first resist film 32. The resist film 31 is removed.

By doing the above, the general pad 2-2
High-melting point solder bumps 20 are provided on the top, and the selected pads 2-
A high melting point cream-like solder 25 may be provided on the top of the 1, and a low melting point solder bump 21 may be provided on the high melting point solder bump 20 in an overlapping manner.

[0036]

As described above, according to the present invention, only the high melting point solder bumps are provided on the general pads of the circuit board on which the general pins of the PGA type semiconductor component are reflow soldered.
A semiconductor component mounting structure in which a composite bump in which a low melting point solder bump is superimposed on a high melting point solder bump is provided on a selected pad of a circuit board for reflow soldering a selected pin on the outer periphery of an A-type semiconductor component. Therefore, after the reflow soldering of the pin of the PGA type semiconductor component and the pad of the circuit board, the adjustment work of the alignment is easy and the alignment accuracy is high, which is an excellent effect in practical use.

Further, according to the method of manufacturing a composite bump of the present invention, only the high melting point solder bumps formed on the necessary selected pads do not cover the entire surface of the high melting point solder bumps, but the tower shape is formed on the upper surface thereof. The low-melting-point solder bump can be provided so as to overlap with.

That is, since the composite bumps are stacked in a tower shape, it is easy to make the plan shape of the obtained bump smaller than the plan shape of the pad. Therefore, even if the solder bumps are reflow-soldered, there is no fear of flowing out from the pads, and the reliability of insulation between the adjacent pads is high.

[Brief description of drawings]

FIG. 1 is a diagram of an embodiment of the present invention, in which (A) is a cross-sectional view of a main part and (B) is a plan view of a circuit board.

2 (A) and (B) are views for explaining the operation of the present invention.

3 (A), (B), (C), (D), (E), and (F) are sectional views showing the manufacturing process of the present invention.

FIG. 4 is a view of a conventional example, (A) is a cross-sectional view after surface mounting, and (B) is a cross-sectional view of a main part before mounting.

[Explanation of symbols]

1 circuit board 2 pad 2-1 selected pad 2-2 general pad 5 PGA type semiconductor component 6 pin 6-1 selected pin 6-2 general pin 10 solder bump 20 high melting point solder bump 20A high melting point solder 21 low melting point solder Bump 21A Low melting point solder 25 High melting point creamy solder 26 Low melting point creamy solder 31 First resist film 32 Second resist film

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location 8617-4M Q

Claims (2)

[Claims] 1. A device for surface-mounting a PGA type semiconductor component on a circuit board by reflow soldering, wherein the PGA type semiconductor component (5) arranged on the circuit board (1).
The high-melting point solder bumps (20) are formed on the general pads (2-2) corresponding to the general pins (6-2) of the PGA type semiconductor components (5) arranged on the circuit board (1).
A high-melting point solder bump (20) is formed on the selected pad (2-1) corresponding to the selected pin (6-1) on the outer periphery of the high-melting point solder bump (20). Melting point solder bump (2
1) A mounting structure of a conductor component, which is formed by overlapping. 2. Selected pads on the surface of the circuit board (1)
(2-1) and the general pad (2-29) having a window above the first resist film (31) made of a heat-resistant resin, the selected pad (2-1) and the general pad (2-1) The high melting point creamy solder (25) is applied to the surface of the pad (2-2), and the high melting point creamy solder (25) is heated to a predetermined temperature, and each of the selected pads (2-1) Then, solder is deposited on each of the general pads (2-2) to provide high melting point solder bumps (20), and then the high melting point solder bumps (20) of the selected pad (2-1) are provided.
A second resist film (32) made of a heat resistant resin having a window on the upper side of the circuit board (1) is provided on the circuit board (1), and then the high melting point solder bump (2) of the selected pad (2-1) is formed.
The low melting point creamy solder (26) is applied to the surface of (0) and the low melting point creamy solder (26) is heated to a predetermined temperature, and the high melting point of each selected pad (2-1) is melted. Solder bump (20)
A low melting point solder bump 21 is superposedly formed by depositing solder on the second resist film (32) and the first resist film (3).
A method of manufacturing a solder bump, which comprises removing 1).