JPH0362990A - Soldering of semiconductor chip carrier - Google Patents

Abstract

PURPOSE:To obtain good continuity and junction strength by a method wherein, when a terminal pin is dipped in a solder bath to be attached to a printed wiring board and when a solder film is formed on an exposed part of the terminal pin, solder bath temperatures are respectively specified. CONSTITUTION:When a terminal pin 7 inserted in a throughhole 6 of a printed wiring board 3 is dipped in a solder bath for forming this terminal pin 7 on the printed wiring board 3, the solder bath temperature shall not be less than a melting temperature of working solder plus 30 deg.C. The reason why is that, in case the solder bath is not performed not less than the melting temperature plus 30 deg.C of the working solder, surface tension of a solder liquid is small so that the solder liquid does not rise ut to the top surface of the buried part 8 of the terminal pin 7 accordingly lacking continuity and junction strength. Next, when a solder film is to be formed on the exposed part 9 of the terminal pin 7, a solder bath temperature shall not exceed the melting temperature plus 30 deg.C of the working solder. That is because, when the solder bath temperature exceeds the melting temperature plus 30 deg.C of the working solder, a solder quantity to be stuck can not be increased thus being unable to improve continuity and junction strength in the mounting for soldering with a mother board.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for soldering a semiconductor chip carrier for mounting a semiconductor element.

(Prior art) In recent years, as semiconductor chips have become more sophisticated and highly integrated, I1
A pin grid array (hereinafter referred to as PGA), in which terminal pins are inserted into through holes of a printed wiring board, has been developed and used as a semiconductor chip carrier to cope with the increase in the number of zeros. From the structure and usage of this PGA, (1) good conductivity and bonding strength between the through-hole plating formed in the through-hole of the printed wiring board, which is the main material, and the terminal pin inserted into the through-hole and soldered; 2) In mounting the PGA terminal pins by inserting them into through-holes on the motherboard and soldering them, it is essential that the conductivity and bonding strength between them be good.

Therefore, in order to improve the conductivity and bonding strength in (1), it is necessary to fill the through holes of the printed wiring board of the semiconductor chip carrier with sufficient solder, and in order to improve the conductivity and bonding strength in (2), It is necessary to apply sufficient solder to the terminal pins.

Conventionally, the exposed part of a terminal pin with an embedded part inserted into a through-hole of a printed wiring board is immersed in a solder bath, and the surface tension of the solder liquid is used to apply solder liquid into the gap between the through-hole and the embedded part. A common method was to raise the In this case, the surface tension is in a positive proportion to the solder bath temperature, so in order to sufficiently fill the through-hole with solder, it has been done by immersing it in a solder solution kept at a high temperature. There was a small amount of solder attached to the exposed parts of the terminal pins, and there were problems with conductivity and bonding strength when mounting them by inserting them into through-holes on the motherboard and soldering them.

[Problem to be solved by the invention]

It is an object of the present invention to provide a method for soldering a semiconductor chip carrier in which the amount of solder attached to the exposed portions of terminal pins soldered with a sufficient amount of solder in the through-holes of a printed wiring board serving as the semiconductor chip carrier is increased.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a method for attaching embedded portions of terminal pins to a printed wiring board by soldering, and forming a solder film on the exposed portions of the terminal pins by inserting the terminals into through-holes of the printed wiring board. When attaching the terminal pin to a printed wiring board by dipping the pin in a solder bath, the temperature of the solder bath should be at least 30°C above the melting temperature of the solder used, and then when forming a solder film on the exposed part of the terminal pin, the solder bath should be The present invention provides a method for soldering semiconductor chip carriers, characterized in that the soldering is carried out at a temperature below the melting temperature of the solder used +30"C.

This invention will be explained in detail below.

First, a printed wiring board according to the present invention will be described with reference to the drawings. The semiconductor chip carrier 2 on which the semiconductor chip l is mounted is, for example, a glass cloth base epoxy resin copper clad laminate, a glass cloth base polyimide resin copper clad laminate, a glass cloth base fluororesin copper clad laminate, a glass cloth base material An electrical circuit 4 is provided on a printed wiring board 3 such as a PP○ resin copper-clad laminate, a modified resin copper-clad laminate thereof, or a copper-clad laminate with a fiber cloth base material having excellent heat resistance. The electric circuit 4 and the semiconductor chip 1 are connected via a metal wire 5, and the semiconductor chip 1 is further sealed with a cap 12 made of hardened resin such as epoxy resin, imide resin, or silicone resin.

The printed wiring vi3 used in this way includes:
It has a through hole 6 formed on the inner surface with a plating that is electrically connected to the electric circuit 4, and the embedded part 8 of the terminal pin 7 is connected to this through hole 6 via solder. It is used by connecting through solder.

When attaching the terminal pins 7, for which conductivity and bonding strength are issues, to the printed wiring board 3 of the semiconductor chip carrier 2 by soldering, the terminal pins 7 inserted into the through holes 6 of the printed wiring board 3 are immersed in a solder bath. When attaching the terminal pin 7 of the lever to the printed wiring F1.3, the solder bath temperature must be at least 30'C above the melting temperature of the solder used.This is because the solder bath temperature must be at least 30'C above the melting temperature of the solder used. This is because the solder liquid does not rise to the top surface of the embedded portion 8 of the terminal pin 7 because the surface tension of the liquid is low, and therefore conductivity and bonding strength are lacking. To give one specific example, is it solder liquid? ! 240-270℃, immersion time 2-5 seconds,
When carried out at a pulling rate of 30-7 Q m/sac, the soldering in this case achieves its initial purpose.

Next, when forming a solder film on the exposed portion 9 of the terminal pin 7, the solder bath temperature is set to be lower than the melting temperature of the solder used by +30°C. This is because if the solder bath temperature exceeds the melting temperature of the solder used +30''C, the amount of solder attached cannot be increased, and there is no improvement in conductivity and bonding strength when soldering to the motherboard. In this case, if the time of immersion in the solder bath is limited to 1 second or less, the solder solidified in the first soldering described above will not re-melt and cause poor continuity and a decrease in joint strength. When pulling up the semiconductor chip carrier to which the terminal pins 7 are attached from the solder bath to be attached, it is effective to do so at a speed of 10 m/Sec or more in that the adhered solder film becomes more uniform.Exposing the terminal pins. A thicker solder film improves solder wettability, which is also effective in improving conductivity and bonding strength in mounting where terminal pins are inserted into through-holes on the motherboard and soldered.

In addition, the solder used has S n / P b of 63/37.
Ordinary solder such as 90/10 ratio solder can be used.

(Example) Example 1 A plated through hole with a diameter of 0.5 mm and a length of 5 .5 aos
Insert the terminal pin of the phosphor bronze base material into the 120-pin PG
The zero-order soldering that made the initial assembly of A had a melting temperature of 1.
Solder with S n /P b of 63/37 at 83° C. was used. The first soldering was carried out at a soldering bath temperature of 250°C, a dipping time of 2 seconds, and a pulling speed of 60 mtm/see.
For the second soldering, the solder bath temperature is 20o'c, and the immersion time is 0.5
A 120-pin PGA was fabricated at a pulling speed of Looms/sec. The thickness of the solder attached to the terminal pins of this 120-pin PGA was measured using fluorescent X-rays, and the average values are shown in Table 1. In addition, the filling rate of solder in the through-hole is
If the through-hole part from which the terminal pin does not protrude is filled with solder, it is considered that the through-hole is filled with solder. 120 through-hole parts from which the terminal pin does not protrude are examined with a microscope, and the solder The number of solder fillers out of 120 that have good filling is the solder filling rate.
The results are shown in Table 1.

Example 2 Using the same materials as in Example 1, the first soldering was performed under the same conditions, and the second soldering was performed at a solder bath temperature of 190'C.
1 immersion time is 1 second, pulling speed is 100 m/see,
Evaluations were made in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 Using the same materials as in Example 1, after the first soldering was performed under the same conditions, the second soldering was performed at a solder liquid temperature of 240°C, a dipping time of 1 second, and a pulling rate of 100 u/see. Evaluations were made in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 2 Using the same materials as in Example 1, the first soldering was performed under the same conditions, and then the second soldering was performed at a solder solution temperature of 240°C, 1 immersion time of 1.5 seconds, and a pulling speed of 100 mm/sec. The evaluation was carried out in the same manner as in Example 1, and the results are shown in Table 1.

Table 1 Example 3 Soldering in Example 1 was carried out under different conditions, including the pulling speed as shown in Table 2. The thickness of the solder attached to the terminal pins was measured using fluorescent X-rays, and the average value was calculated. It is shown in Table 2.

Example 4 The second soldering in Example 1 was performed under different conditions, such as the pulling speed as shown in Table 2. The thickness of the solder attached to the terminal pin was measured using fluorescent X-rays, and the average value was calculated. It is shown in Table 2.

Comparative Examples 3 to 5 The second soldering in Example 1 was performed under different pulling speeds as shown in Table 2, and the thickness of the solder adhering to the terminal pins was measured using fluorescent X-rays, and the average The values are shown in Table 2.

Table 2 From Table 1, use the solder bath temperature in (a) Solder melting temperature +
If the second soldering is carried out at 30°C or less and the immersion time in (b) is 1 second or less, the thickness of the solder adhering to the terminal pin will be 3μ or more, and the degree of solder filling in the through hole will be 9.
It was confirmed that the reduction could be made to 0% or higher. Also, from Table 2,
It was confirmed that when the second soldering was performed at a pulling speed of 70 a/sec or more in (c), the thickness of the solder adhering to the terminal pins could be increased to 3 μm or more.

(Effects of the Invention) According to the present invention, it is possible to sufficiently fill the through holes of the printed wiring L% +ffl with solder, and also to sufficiently adhere the solder to the exposed portions of the terminal pins, and as a result, the semiconductor having such terminal pins can be This has the effect of providing good conductivity and bonding strength when the chip carrier is inserted into the through-hole of the motherboard and soldered.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one example of the usage state of the semiconductor chip carrier according to the present invention. 1... Semiconductor chip 2... Semiconductor chip carrier 3... Printed wiring board 4... Electric circuit... Metal wire... Through hole... Terminal pin... Embedded part... Exposed Part... Motherboard... Sulfo -J... Capped

Claims (1)

[Claims] (1) Attach the embedded part of the terminal pin to the printed wiring board by soldering and form a solder film on the exposed part of the terminal pin by immersing the terminal pin inserted into the through hole in the printed wiring board in a solder bath. When attaching terminal pins to a printed wiring board, use the solder bath temperature.Solder melting temperature +
A method for soldering a semiconductor chip carrier, characterized in that soldering is carried out at a temperature of 30° C. or above, and then, when a solder film is formed on the exposed portion of a terminal pin, the soldering bath temperature is carried out at a melting temperature of the used solder plus 30° C. or below.