JPH01181454A - Pin junctioning method to ceramic package for integrated circuit - Google Patents

Abstract

PURPOSE:To increase production efficiency and reliability in quality, by standing a pin inverted on a package, in the manner in which soldering material grain body of a pin-tip part is brought into contact with the metallized surface of a ceramic package, and the pin is soldered with the package by heating at a melting temperature of the soldering material in a non- oxidizing atmosphere under the above state. CONSTITUTION:Soldering material powder is subjected to kneading together with organic binder, and glanulated to obtain grains 16, which are mounted on the tip parts of ins 14, and pressed and bonded to pin-tips 12. By processing at a low temperature of 150-380 deg.C, the greater part of organic component is gasificated and evaporated. While the grain shape of the soldering material is kept by using tar-pitch type material produced in the above process, said material is fixed on the pin-tip parts 12. When the soldering material is bonded to the pin-tip, the soldering material is not melted different from the conventional method. Therefore when the soldering material is bonded to the pin-tip parts 12, the soldering material is not bonded in the state where a part of the material suspends on the tip side surface of the pin 14, so that the whole surface of the pin 14 is perfectly plated when the pins 14 are plated in the later process. The process in which the soldering material is heated at a high temperature and melted is finished by a single process, so that the production efficiency and the reliability of quality are increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of joining a signal extraction pin to a ceramic package for an integrated circuit, particularly a method of joining by brazing.

(Conventional technology) a! The ceramic package for the planter circuit has pins connected to take out the signal to the outside, but VLS, which has a high degree of integration,
Since a package for an I (very large scale integrated circuit) has a significantly large number of pins (generally 80 to 300), a pin grid array system is used in which the pins are arranged in a grid on the surface of the package.

FIG. 5 shows an example of a method for joining (brazing) pins in such a pin grid array package.
To explain each step of this method based on the drawings, 100 is a pin (generally 42 mm diameter) consisting of a shaft portion 102 with a diameter of 0.45 mm and a length of about 4.5 mm, and a head 104 with a slightly larger diameter. %Ni
As shown in Figure (C), the hole 1 of the holding mold 106 is made of graphite or the like using a parts feeder.
Set to 08. On the other hand, as shown in Figure (B), a thin wire of brazing material (generally 28% Cu sheet wax) 110 is cut into a predetermined size to form a chip 112, which is placed on the head 104 of the pin 100 set in the hole 108. In this state, the holding mold 106 is heated in a furnace with a non-oxidizing atmosphere such as a hydrogen atmosphere to melt the brazing filler metal chip 112, and the pin head 1 is heated.
Weld it to 04. At this time, the molten brazing filler metal takes on an inverted dish-like shape due to surface tension, as shown in Figure (D), and solidifies as it is.

After welding the brazing material to the pin head 104, the pin lOO is removed from the holding mold 106 and placed in a brazing mold 116 prepared separately using a parts feeder or the like, as shown in Figure (E).
(The pitch P between each perforation fiB 118 is equal to the arrangement pitch of the pins in the ceramic package 120). Each pin 10 is pressed into contact with the metallized surface 122 formed on the
0 is held by the soldering die 116, and the package 1 is
20 and heated to the melting temperature of the brazing material in a furnace with a non-oxidizing atmosphere such as a hydrogen atmosphere, and the pin 100 is brazed to the package 120. Then cool down and pin 1
00 is removed from the mold 116.

(Problem to be Solved by the Invention) By the way, in this method, the pin 100 is
or to make it easier to take out the set pin 100 from the holding mold 10B after welding the brazing material.

As shown in FIG. 6, it is common to provide a predetermined amount of clearance CI, C2 between the pin lOO and the inner surface of the perforation 108. However, in this way, clearance CItC2
When the brazing filler metal chip 112 placed on the head 104 of the pin 100 is melted, a portion of the brazing filler metal chip 112 is placed on the head 104 of the pin 100.
4 and the inner surface of the perforated portion 108 and adheres to the side surface of the pin head 104. If the brazing material adheres to the side surface of the pin head 104 in this way, the pin Even after the pin 100 is brazed to the ceramic package 120, the brazing material remains on the side surface of the pin 100, and when plating the surface of the pin 100 later, the plating will not adhere well to the rounded portion.

That is, in the above-mentioned grid array package, the purpose is to improve the electrical conductivity of the pins to the socket, or to improve the solderability to the printed circuit board.

In addition, in order to provide rust resistance, pin 1 was removed in the final process.
00 is subjected to gold plating, solder plating, etc., but the optimum plating conditions at that time vary depending on the material of the base material, so if the optimum plating conditions are set for the pin 100, the adhesion of plating at the part where the brazing material is attached becomes poor, This is the only area where the plating will not adhere completely.

Another problem with this method is that the production efficiency is low.

In the water splash process, the chip-shaped brazing material placed on the pin head 104 is heated and welded to the pin head 104, and the brazing material welded to the pin head is melted again to form the metallized surface of the ceramic package 120. The two brazing processes of welding to 122 are repeated, and VL
In the case of SI packages, 28% Cu silver solder, which has a high melting point, is generally used as the brazing material, so the brazing temperature is as high as 800°C. The brazing process requires high-level control of conditions, such as brazing in an oxidizing atmosphere. Because such high-temperature treatment is repeated twice, production efficiency is reduced.

(Means for solving i[?i) The present invention was made to solve such problems, and its gist is to add an organic binder to brazing filler metal powder that has been pulverized to a certain amount or less in advance. is added and kneaded, and the granules granulated from the kneaded product are pressed and adhered to the head of the pin, and then held at a temperature of 150 to 380 ° C. for 5 minutes or more in a non-oxidizing atmosphere, The pin is placed upside down on the package so that the brazing filler metal granules on the pin head are in contact with the metallized surface of the ceramic package, and in that state, the pin is heated to the melting temperature of the brazing filler metal in a non-oxidizing atmosphere. to the package.

(Function) As described above, in this method, the brazing filler metal powder is kneaded with an organic binder and granulated into granules, which is placed on the head of the pin, and is pressed to adhere to the head of the pin. Then, by treating this at a low temperature of 150°C to 380°C, most of the organic components are gasified and volatilized, and the tar and pitch-like substances generated at that time change the granular shape of the brazing material. While holding it, secure it to the pin head. In other words, unlike conventional methods, the solder metal is not melted when it is joined to the pin head, and therefore, when the solder metal is joined to the pin head, a portion of the solder metal hangs down on the side of the pin head. Therefore, when plating the pin later, the plating adheres well to the entire surface of the pin.

Further, according to the present invention, the process of heating the brazing material to a high temperature and melting it only needs to be done once, thereby improving the production efficiency and further increasing the reliability of quality.

It should be noted that at the stage of heating and melting one grain of brazing material, the tar and pitch-like substances remaining within the grain are decomposed and volatilized, but since the amount thereof is small, the volatilization is carried out gently. Therefore, at that time, a large number of pores are not generated in the brazing material portion.

In the present invention, as a desirable means for adhering the brazing filler metal granules to the pin head, the binder itself has adhesive properties, and when the brazing filler metal granules are pressed against the pin head, the adhesive force causes the particles to stick to the pin head. One method is to glue it to the pin head.

Another method is to apply an organic adhesive to the brazing filler metal granules and/or the pin head in advance, and when the brazing filler metal granules are pressed, the adhesive acts to adhere them to the pin head. can be mentioned.

In either case, most of these binders and adhesives are gasified by the subsequent low-temperature heat treatment, and some remain as tar and pitch-like substances, which continue to function as a binder.

(Example) Next, embodiments of the present invention will be described in detail based on the drawings.

As shown in FIGS. 1(A) and 1(B), the shaft portion 10, the head portion 1
A pin 14 consisting of two pieces and a spherical brazing filler metal granule 16 are prepared.

The brazing filler metal granules 16 are generally made by adding a certain amount of an organic binder to a brazing filler metal that has been powdered by gas spraying in an oxidation-preventing atmosphere, kneading the mixture, and granulating the kneaded product using a granulator. It is obtained by

The binder is mainly composed of a high molecular weight polymer, to which a tackifying component is added, and the amount added to the brazing filler metal powder is 3 to 15% by volume. However, the addition of this tackifying component is not essential, and is not necessary when the brazing material granules 16 are bonded to the pin head 12 by applying an adhesive as described later.

Next, as shown in Figure (C), the pin lO is set in the perforation 20 of the holding mold 18, and then the brazing filler metal particles 16 are placed on the center of the upper surface of the pin head 12 and pressed by the pressing mold 22. The particles 16 are made into a flat shape (see figure (D)), and at this time, the particles 16 are adhered to the pin head 12 by the adhesive force of the binder. Incidentally, if the side of the press die 22 is treated with Teflon coating or the like, it is possible to prevent the brazing filler metal particles 16 from sticking to the side of the press die 22.

After the granules 16 are attached to the pin head 12, the pin 14 is taken out from the holding mold 18, heated to a temperature of 150 to 380°C in a non-oxidizing atmosphere such as argon gas, and held for 5 minutes or more. Then cool.

Through this heating process, most of the binder contained in the granules 16 is gasified and volatilized, and some of the decomposition/polycondensates are turned into tar,
It remains as a pitch-like substance and binds the brazing filler metal powders together, as well as bonding the brazing filler metal particles 16 and the pin head 12.

After this heat treatment is completed, as shown in Figure (E), pin 1
4 to the perforated part 26 of the brazing mold 24 using a parts feeder.
the solder metal granules 16 on the pin head 12.
While pressing the pin 14 into contact with the metallized surface 30 of the ceramic package 28, the pin 14 is pressed together with the mold 24 into the package 2.
8 and placed in a furnace in a non-oxidizing atmosphere such as a hydrogen atmosphere and heated to the melting temperature of the brazing filler metal.

Pin 14 is brazed to package 28.

The bonding force due to the tar and pitch-like substances can sufficiently withstand vibrations during setting by the parts feeder, and also has a temperature of 500 to 600, at which the powder of the brazing filler metal starts solid-phase sintering when the brazing filler metal is heated and melted. Can withstand temperatures up to ℃.

[Experiment example] A 42% Ni steel wire rod with a diameter of 0.45 mmφ was cut to a specified length using a header machine, and the head was swaged. As shown in Fig. 2, the length was 4.6 mm, and the shaft was lO. And the diameter of the head 12 is h d l = 0.45 mmφ, d2 = 0.7
Pin 1 with thickness t of head 12 = 0.2 layer size with φ
4 was manufactured. On the other hand, 28% Cu silver solder (JIS BAg8) was used as the brazing material, which was made into powder by gas spraying and had a particle size of #150 under, to which 10% by volume of acrylic resin binder was added, and a mixer After kneading for 30 minutes, the mixture was granulated into approximately spherical particles with a diameter of approximately (+, 62 sv).The weight of the granules was approximately 0.93 mg.

Next, after washing and drying the pin 14, the hole i9 [1
20 and place the brazing filler metal granules 16 on top of 1112, and as shown in FIG.
．． The 35-layer intestine was compressed and flattened, and at the same time, it was adhered to the pin head 12 using the binder in the granules 16.

Subsequently, this brazing material adhesive pin 14 was taken out from the holding mold 18, and the temperature was raised to 250°C at a heating rate of 15°C/min in a mixed gas atmosphere furnace of argon gas and 3% hydrogen gas, and kept at that temperature for 30 minutes. After being held, it was cooled.

Next, as shown in Fig. 4, the ceramic package 2
The pins 10 are set in the perforations 26 of the soldering mold 24, which are formed at the same pitch interval P = 2.54 mm at the pin soldering position of No. The temperature was raised to 900°C at a heating rate of 20°C/min in a gas atmosphere furnace, and then cooled.

The ceramic package 28 was made of alumina, and the bottom surface thereof was metalized with W (tungsten) at the positions shown in FIG. 4.

Furthermore, the brazing Y1124 was made of graphite.

In this way, the ceramic package 28. Pin 14.
As a result of high temperature treatment of the set type such as the brazing die 24, the brazing material melted, and the pin 14 and the ceramic package 28 were brazed together at the metallized surface 30. No brazing material was attached to the side surface of the pin head 12, and therefore the subsequent plating performance was also good.

Although the thirteenth embodiment has been described in detail above, the present invention can also be implemented in other embodiments.

For example, in clay figurines, a binder that is adhesive itself is used to bind the brazing material powder, but adhesives such as epoxy resin are used on both the brazing material particles and the pin head, or on either one of them. may be applied in advance, and the two may be firmly adhered at room temperature or during the low-temperature heat treatment.

In addition, various types of binders can be used as the binder, and the shape of the brazing filler metal particles does not necessarily have to be spherical, and there is no particular problem even if the shape is a flat disk.
The present invention can be implemented in various modified forms without departing from the spirit thereof.

(Effects of the Invention) As detailed above, according to the present invention, the brazing metal does not adhere to the side surface of the pin head, and when the pin is subsequently plated, the plating performance is improved and production efficiency is improved. Moreover, excellent effects such as improved quality reliability are produced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for explaining the steps of a brazing method that is an embodiment of the present invention, FIG. 2 is a front view showing each radical method of the pin manufactured in the experimental example, and FIG. FIG. 2 is an enlarged cross-sectional view of a main part showing the compression process of the brazing filler metal granules in the same experimental example. Fig. 4 is a diagram showing the arrangement pattern and positional dimensions of pins in a ceramic package, Fig. 5 is an explanatory diagram showing the steps of the conventional brazing method, and Figs. 6 and 7 are diagrams showing the defects of the same method. It is an explanatory diagram for explanation. 12: Head 14: Pin 16: Brazing material granules 18: Holding mold 24: Brazing mold 28: Ceramic package 30: Metallized surface

Claims (3)

[Claims] (1) A method in which a large number of pins for external signal extraction are brazed upside down on the surface of a ceramic package for integrated circuits, and an organic binder is added to brazing filler metal powder that has been pulverized to a certain size or less in advance. The granules granulated from the kneaded product are pressed and adhered to the head of the pin, and then held at a temperature of 150 to 380°C for 5 minutes or more in a non-oxidizing atmosphere. The pin is placed upside down on the package so that the filler metal granules in the area are in contact with the metallized surface of the ceramic package, and in that state, the pin is heated to the melting temperature of the filler metal in a non-oxidizing atmosphere to attach the pin to the package. A method of pin joining to ceramic packages for integrated circuits, characterized by brazing. (2) A patent characterized in that the organic binder is adhesive, and based on the adhesive property, the brazing filler metal particles are adhered to the pin head when the particles are pressed against the pin head. A pin joining method according to claim 1. (3) At least one of the brazing filler metal granules and the pin head is coated with an organic adhesive in advance, and when the brazing filler metal granules are pressed against the pin head, the adhesive acts on the particles. Claim 1 or 2, characterized in that the body is bonded.
Pin joining method described in section.