JPS6049862A - Production of laminated cooling body formed of aluminum - Google Patents

Abstract

PURPOSE:To obtain inexpensively a cooling body which is light in weight and is highly resistant to corrosion by combining suitably Al post parts subjected to specific plating and cooling fins coated with copper in the parts that contact the post parts as well as annular solder and joining the assembly by heating. CONSTITUTION:A bar material 1 consisting of Al or the alloy thereof is cut to a prescribed length and copper coating and electric copper plating are formed successively over the entire surface then silver is locally plated only on the required part thereby forming a post part 3. An Al plate material 4 is pressed to a prescribed shape and after the hole part to be joined to the post part 3 is burred, a copper 7 is coated in the hole part, thereby forming a cooling fin 6. Wire-shaped copper flux-contg. solder is further formed into an annular shape of which the inside circumference is the outside circumference of the post. The fins 6 and the solder 8 are successively laminated by a required number on the post part 3 and the assembly is put into a heating furnace to solder the same by heating and thereafter the assembly is taken out of the furnace and is cooled. The flux is washed away.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides aluminum or an alloy thereof (hereinafter referred to as Al,
The present invention relates to a method for manufacturing semiconductors and cooling bodies manufactured by Miniram.

Conventionally, many laminated cooling bodies were made of copper, including a part of the boss 1 and the cooling fan.However, since it was heavy and expensive, the boss part was made of aluminum.
7 58774”ff, No. 58-81416.

However, this has the disadvantage that it is still quite heavy and expensive, and there is a difference in the expansion coefficient between the boss I section and the cooling fins, and thermal fatigue tends to occur near the joints. Therefore, in the 5th year of Utility Industry, the boss part and cooling fins were made of aluminum.
There is No. 1-92169.

However, in this case, the entire surface of the cooling fin + Ni is also coated with copper, but there is a drawback that the cost of coating is high. In addition, there is a drawback that the solder joints of the copper components are subject to discoloration unless done in a reducing or inert atmosphere. or,
Another laminated cooling body is one in which aluminum brazing fins are coated with copper, but the masking process for partial coating is complicated, and even if the entire surface is plated, the plating cost is high.

The present invention has been made in view of the above-mentioned drawbacks, and its gist is that after processing an aluminum bar material into a predetermined shape, the entire surface is coated with copper, and further electrolytic copper plating is applied. There is a post forming process in which local silver plating is applied only to the contact surface with the element, and after the aluminum plate is press-formed into a predetermined shape, a small copper coating is applied to the part in contact with the post. [obtained cooling]; a ring-shaped solder forming process in which linear copper-containing solder is formed into a ring shape; and a necessary number of cooling fins and ring-shaped solder are sequentially laminated on the post s, and then heated and cooled. and washing.

Next, each step of the present invention will be explained in order.

1. Bost part forming process: Cut an aluminum bar into a predetermined length required for the boss part. Furthermore, after cutting to a predetermined thickness, the entire surface is coated with copper.

Copper coating in this case is performed, for example, by the method disclosed in Japanese Patent No. 527777 or Japanese Patent No. 1085694. As a result, a strong copper wave Oi layer is formed on the surface of the aluminum. Electrolytic copper wood is further applied to the second part of the copper coating layer. This increases the thickness of the copper layer, increases the anticorrosion effect, and improves the strength of solder joints with cooling fins in the subsequent process. In addition, ordinary silver plating is applied only to a local portion of the cut plane portion of the boss portion that contacts the contact surface of one of the semiconductors. This is it.

This improves compatibility with the semiconductor element to be bonded, and reduces thermal and wax resistance. Furthermore, almost no change occurs over time. Since the boss portion is simply plated with copper and silver on the surface of the aluminum base material, it is possible to obtain a lightweight, highly corrosion resistant boss portion suitable for use as a heat sink cooling body.

2 Cooling fin forming process An aluminum plate is press-formed into a predetermined shape.

In this case, a hole is made in the center for joining with the boss part, or a notch is formed in the center of one side. A burring portion is formed in the hole or notch for joining with the boss portion. The joint portion of this burring portion with the boss portion is coated with copper in the same manner as described above. In this case, masking for partial coverage is performed. For this masking, use a thin plate with cutouts for the areas that need to be covered.

The application of such a copper coating is necessary in order to easily and reliably make solder joints, and to ensure durability. Since the copper coating is applied locally, it is inexpensive, and because the copper coating is applied locally, there is less solder leakage and the finish is beautiful. Furthermore, no discoloration of the cooling fins occurs. If necessary, the cooling fins may be press-molded with wavy or local protrusions at the same time to improve the cooling effect.

3. Annular solder forming step A linear copper-containing resin-containing solder is formed into an annular shape with the outer periphery of the pot as the inner periphery. In this case, the solder is a linear solder having a volume necessary for joining the boss portion and the cooling fin, and preferably contains copper.

This is because with solder that does not contain copper, the coated copper will diffuse into the solder, making the copper piece thinner and reducing the bonding strength. Also, the workability is better with resin. By pre-forming the annular T, it is possible to improve the workability without any unevenness or waste for later soldering. After sequentially laminating the necessary number of annular solders, the bot part is put into a heating furnace to perform solder joints, and then taken out and cooled, and the flux is washed away.

Both the boss part and the cooling fan are made of aluminum, so they are lightweight. Moreover, since the expansion rate is the same,
Soldering generates less stress in the parts. When soldering the cooling fins, only the parts are coated with copper, so the cooling fins will not discolor even if soldered in the atmosphere. Because it is partially plated, the solder does not flow to unnecessary areas, so the amount of solder can be small.

Next, one embodiment of the present invention will be described based on the drawings.

1 Bost part forming process JIS (JIS) I 4000-AIloo aluminum bar 1i length 45 mm, and further φ84-
It was cut into pieces, immersed in a liquid bath of reaction reagent for copper coating, taken out, and heated in a furnace at an ambient temperature of 400 to 450'C for 20 minutes.
After heating for ~40 minutes, remove and cool in water. Furthermore, copper electroplating is applied to a thickness of 20 μm.

Thereafter, silver plating is further applied to the entire plane part -Z which is in contact with the semiconductor element. The boss portion 3 is thereby formed.

2. Cooling fin molding 1 culm plate thickness 1.2 mm, width 195 m 1) JIS, H4000-
Pressed from AIloo's aluminum plate material 4, length 160mm, height 2.71-11mm with φ84 ridge in the center.
Perform the burring.

A reaction reagent for copper coating is applied to the inner surface of the purling portion 5 of the cooling fin material 6 after being pressed using a masking jig. Next, take out the beading jig. Next, the cooling fin material after coating is heated to an ambient temperature of 400 to 450.
Place in furnace C, take out after 15 to 30 minutes, and cool with water. As a result, cooling fins 6 coated with copper 7 are formed on the purling portion 5 .

8 Annular half U] Molding process resin half 1J312aIIφ solder wire to inner diameter φ8
4mm 0) Form an annular solder 8.

4. Laminated cooling body forming/post-processing process Set the boss 1 part 3 upright, first put the annular solder 8 in it, then fit the first cooling fin 6 to the boss part, and half 11.
and the cooling fins are brought into contact with each other. Next, the second annular solder, the cooling pipe, etc., and the boss part were heated to an ambient temperature of 300°C.
It was placed in a furnace C, and after 15 to 20 minutes, it was taken out, cooled with forced air, and the furanokunu was removed by washing with hot water. Because it was covered with aluminum + tin, it was possible to prevent the silver plating from discoloring for 1 hour.

The obtained laminated cooling body was lightweight, suffered little thermal fatigue, had no discoloration or solder flow, was cleanly and firmly bonded, and had excellent corrosion resistance.

[Brief explanation of the drawing]

One drawing shows one embodiment of the present invention, FIG. 1 is an explanatory view showing one manufactured culm, and FIG. 2 is an explanatory cross-sectional view before joining. 1 Ni-Al Reminium Bar Material 2: Contact Surface 3: Bost Part 4 Ni-Aluminum Plate Material 5: Purling Part 6: Cooling Fin 7: Copper Coating 8; Annular Half 8] Patent Applicant

Claims (1)

[Claims] After cutting a bar of aluminum or its alloy (hereinafter simply referred to as aluminum) to a predetermined length, the entire surface is coated with copper, and further electrolytic copper plating is applied to the surface in contact with the semiconductor element. The cooling fin forming process involves press-forming an aluminum plate into a predetermined shape and then applying copper coating to at least the portion in contact with the boss. ε An annular solder forming step in which the copper-containing solder l is formed into an annular shape with the outer periphery as the inner periphery, and a necessary number of cooling fans and annular solder are sequentially laminated on the bottom part, and then heated, cooled, and washed. A method for producing an aluminum laminated cooling body, comprising the steps of: