JPS59151492A - Method an ddevice for soldering electronic part - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for connecting electronic components by soldering and a soldering device used in the method.

With the recent development of microelectronics, demands for ultra-miniaturization, high density, and high reliability of electronic component mounting technology are increasing. Along with this, various improvements have been made to methods and devices for soldering electronic components. In addition to conventional methods using electricity (1) heaters, attempts have been made to use lasers, microwaves, etc. to heat and melt solder; I am doing soldering. However, when moving electronic components with melted solder, as solder connections become finer and more dense,
The probability of a short circuit occurring at the connection increases due to positional displacement due to vibration during movement.

Further, after heating the solder joints, a slow cooling method or a natural cooling method has been used. This is because residual stress in the connection due to the difference in thermal expansion coefficient between the electronic component and the wiring board has been considered a problem, and in order to reduce this residual stress, it has been considered desirable to cool the component as slowly as possible. However, as seen in Josephson circuit mounting, which is one of the leading candidates for next-generation computers, from the perspective of matching thermal expansion coefficients, if St substrates are used for both the connecting dizzo and the wiring board, The problem with cooling rate is solved. ′ □ The present inventors have developed the Josephson chip flip/Q
) By researching the bonding process and rapidly cooling the solder joints, the elongation of the solder was improved six times compared to natural cooling, and the stress of the connections was alleviated. We found that the reliability of the system was significantly improved. The present invention has been made based on this knowledge, and it is possible to connect shim parts by melting the solder at the connection part and then rapidly solidifying it at that position when connecting electronic parts using solder. The purpose is to achieve high-density, fine solder connections with high reliability, and to significantly improve the strength of the solder connections. Incidentally, the present invention is also applicable to the case of connecting ceramic substrates such as chip carriers.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which 1 is a soldering stand;
2 is a cooling pipe, 2' is a heating pipe, 3 is a solenoid valve, 4 is a constant temperature bath for a heating medium, 5 is a constant temperature bath for a cooling medium, and 6 is an electronic component and a wiring board to be soldered. In this embodiment, the soldering table 1 is made of a copper block with high thermal conductivity, and has a hollow structure, in which the heating and cooling medium is supplied to the pipes 2 and 2.
It has a structure where water flows in and out. Distilled water is used as the heating and cooling medium, and the constant temperature bath 4 for the heating medium is kept at 70°C.
The constant temperature bath 5 for cooling medium was kept at 10°C, and the sample was low melting point solder (In-Bi-Sns melting point 60°C).
(The shape of the solder connection part is 50 μmφ, 30 μmh, 4 tta
A 4 m chip with 120 connections spaced at 100 Am intervals on four sides was used.

For soldering, place the sample 6 on table 1, and connect the pipe 2.
For soldering, a heating medium is passed through the stand 1, and the temperature of the sample 6 is controlled to 70° C.±1° C. to melt the solder. Next, the heating medium is stopped, the solenoid valve 3 is switched on, and the cooling medium is flowed through the pipe 2 into the soldering table 1, and the sample 6
The solder is rapidly cooled (cooling rate: about 20°C/5ee) to solidify the solder. Table 1 shows the case where this sample was connected to a conventional electric furnace (cooling rate of about 0.1°C/5ee).
This is a comparison of the connection characteristics when using the device of this embodiment.

Table 1 According to Table 1, no conduction failure occurred at the connection portion in either device, but two short circuits occurred in the conventional device. In conventional equipment, the Frizzo tip moves the soldering sample while the solder is melted, which is thought to be the cause of the short circuit.

In addition, a tensile test was conducted on the connected portion, and while the conventional device could only achieve an elongation of 25 inches, the device of this example achieved an elongation of 100 inches. This is because the metal structure of the solder becomes finer by rapidly solidifying the solder using the apparatus of this embodiment. If the elongation of the solder at the connection part is increased in this way, the limit at which breakage occurs when an external force is applied to the connection part is increased, and the reliability of the connection (5) is improved.

Next, another embodiment of the present invention will be described. FIG. 2 shows another embodiment of the present invention, in which 1 is a stand for soldering, 2 is a stand for soldering;
5 is a cooling pipe, 5 is a constant temperature bath for cooling medium, 6 is a soldering sample, 7 is a quartz furnace tube, 8 is a heater, 9 is a thermocouple for controlling the heater, 1° is a power supply and control circuit for the heater It is. In this embodiment, silicone oil maintained at 10°C in a constant temperature bath 5 is used as the cooling medium, and after the solder is melted in an electric furnace, the heater 8 is turned off, and the cooling medium is placed in the cooling pipe 2 (stainless steel). The solder is rapidly cooled by flowing silicone oil (cooling rate of about 10° C./see) to solidify the solder.

Using the device of this embodiment, solder Pb-8n (40:60
wt%) was used to connect the chip carrier sample.

The chip carrier sample has 82 terminals and the terminal shape is 0.51w.
+ Table 2 compares the connection characteristics when this sample was connected multiple times to a conventional device (electric furnace) and when it was connected to the device of Example (6).

Table 2 According to Table 2, no continuity failures or short circuits occurred in the connections in either device, but the elongation rate of the solder in the connections in the tensile test was 20 inches in the conventional device. In the case of the apparatus of this embodiment, the distance is improved to 60 inches.

As explained above, according to the present invention, the connected parts are not moved during solder melting, and the solder is rapidly solidified, so external forces such as vibrations are not applied to the parts during solder melting, and the connection is reliable. This has advantages such as improved properties and improved mechanical properties of the welded parts due to rapid cooling of the solder.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of another embodiment of the invention. 1... Soldering stand, 2... Cooling piping, 2'...
・Heating piping, 3... Solenoid valve, 4... Constant temperature bath for heating medium, 5... Constant temperature bath for cooling medium, 6... Electronic parts and wiring board for soldering, 7... Quartz Furnace core tube, 8... Heater for heating, 9... Thermocouple for heater control, 10...
Heater power supply and control circuit meter

Claims (1)

[Claims] 1. A method for soldering electronic components using solder, which is characterized in that the solder at the connection part is melted and then rapidly solidified at that position to connect the electronic components. □・ 2. An apparatus for soldering electronic components, characterized by being equipped with a cooling device for rapidly solidifying molten solder at a connection part.