JPH0556679B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for manufacturing a laminated cooling fin used in a semiconductor device such as a thyristor.

[Background of the invention]

As the capacity of semiconductor devices such as thyristors increases, it has become an important issue to find an efficient cooling method.
A boiling cooling method is used, which performs cooling by repeatedly boiling and condensing a coolant with good evaporability, such as Freon. As shown in FIG. 5, the boiling cooling device generally consists of a cooling fin 1 for storing a cooling liquid, and a condenser 2 provided above the cooling fin 1.
A pipe 3 made of an insulating material is provided between the cooling fins and the condenser. By the way, in this boiling cooling device, the internal pressure changes from vacuum to 2 to 3 atmospheres depending on the magnitude of the heat load on the semiconductor element 4, so the container must be tightly airtight. Furthermore, the cooling fin is a part that cools the heat from the semiconductor element by boiling freon, and needs to have high cooling efficiency as well as airtightness as described above. For this reason, although research and development has been carried out on the structure of this type of cooling fin and how to manufacture it, the current state is that no technology has been developed that fully satisfies these requirements. It is. That is, conventionally, as shown in FIG. 6, as a method for manufacturing this type of cooling fin, fluid passages within the cooling fin are first formed by extrusion molding or cutting (steps A and B), and then the tubes 7 are formed. , 8 and the side plates (processing C, D), and then weld the bus bar 6 to produce the structural cooling fin shown in Fig. Not only are there many problems in ensuring the properties of the welding process, but also great care must be taken to prevent welding deformation, which is accompanied by technical difficulties. Furthermore, a major drawback of this method is that since the fluid passages are formed by extrusion or cutting, there is a limit to how small the thickness of the fluid passages can be. Reducing the thickness of the fluid passages and increasing their number is an important matter in increasing the heat transfer area and increasing the cooling efficiency.

In addition, a hollow cooling fin as shown in Figure 8 has been considered, but this structure cannot withstand the load of several tons required to secure the semiconductor device to the cooling fin. It has the disadvantage of being deformed. Furthermore, in recent years, there has been a trend toward larger capacities of semiconductor rectifiers, and the devices have also tended to become larger and larger. Since this increase in size causes the problem of an increase in device space, it is desired that the device be made smaller. As a prior art related to the miniaturization of this device, there is
The technique described in Japanese Patent No. 57-49787 is mentioned.
This technology connects semiconductor elements and
A highly thermally conductive insulating material is interposed between the cooling fins and a cooling body having a condenser. However, even with this technology, although miniaturization has progressed to some extent, it has not been possible to achieve fundamental miniaturization, and miniaturization of cooling fins remains the key to miniaturization of semiconductor rectifier devices.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing a laminated structure cooling fin for semiconductors, which allows the shape and dimensions of fluid passages to be arbitrarily set, has high cooling efficiency, ensures airtightness, and is compatible with miniaturization of devices. It is in.

[Summary of the invention]

In order to achieve the above-mentioned object, the conventional cooling fins in which fluid passages are formed by extrusion or cutting and assembled by welding have reached their limits. Based on the idea that we should develop a cooling fin, we conducted extensive research and developed the method for manufacturing cooling fins with a laminated structure described below.

The present invention is a method for manufacturing a laminated structure cooling fin for semiconductors, which is made of laminated metal thin plates with good thermal conductivity and has a fluid passage inside for cooling semiconductor elements mounted on a flat outer surface. First, as a thin plate, a plurality of thin slotted holes are formed in parallel in a first flat plate corresponding to one semiconductor element, and these thin slotted holes are formed in the vicinity of each of the starting and ending ends of the plurality of narrow slotted holes. a second lamella forming a wide slot orthogonal to the slot, and an enlarged slot extending from the wide slot formed in the second lamina to the wide slot including the end of each narrow slot; Three types were manufactured, with a third thin plate formed at the position corresponding to the end of the narrow slot hole, and the bonding surfaces of the three types of thin plates were cleaned in a non-oxidizing atmosphere to form a bonding alloy layer on the bonding surface. , then one first thin plate, one or more second thin plates, one or more third thin plates, one or more second thin plates and one first thin plate. Then, from one side of the bonded laminates in the longitudinal direction of the enlarged slots, the wide slots of the second thin plate and each of the narrow slots are directly opened. It is characterized in that an inlet hole and an outlet hole are formed in the groove, and each groove is used as a passage for fluid.

Specifically, first to third thin plates made of a material with good thermal conductivity, such as copper, aluminum, or an alloy thereof, are manufactured, and when the thin plates are laminated and bonded, in a non-oxidizing atmosphere, After cleaning the bonding surface with an Ar ion beam, etc., a bonding alloy layer is formed by vapor deposition or sputter deposition, and bonding is performed to obtain a laminated structure cooling fin for semiconductors with excellent airtightness. This is what I found. The effectiveness of the present invention will become clearer from the detailed explanation of the configuration described below.

In the present invention, since the fluid passages of the cooling fins 1 are formed by laminating and bonding pre-processed thin plates, unlike conventional extrusion or cutting processes, the fluid passages 5 of any shape and size can be formed. 1
1 can be formed by a relatively simple processing technique such as press punching. It goes without saying that if conventionally known microfabrication techniques such as photoetching and ion beam machining are used instead of press punching, even finer fluid passages can be formed and cooling efficiency can be increased. In addition, in the manufacturing method of the present invention, when laminating and bonding thin plates, after cleaning the bonding surface with an Ar ion beam or the like in a non-oxidizing atmosphere, a bonding alloy layer is further deposited on the bonding surface by vapor deposition or sputter deposition. The technical reason for forming and bonding is due to the following considerations. As mentioned above, cooling fins for semiconductors must be removed from the vacuum at the time of use.
Since a pressure change of about 3 atmospheres occurs, airtightness is an important issue, and it is necessary to strengthen the joint and to facilitate the establishment of precise fluid passages. That is, since the surface of the metal plate used as the raw material is usually covered with a contaminated film or an oxide film, extremely high temperatures and bonding pressures are required to diffusion bond the metal plate as it is, and deformation is therefore likely to occur.
In particular, thin plates made of aluminum or an alloy thereof have a dense and stable oxide film, so joining them is extremely difficult. As a result of various studies on this problem, the present inventors first removed and cleaned the contaminated film and oxide film on the surface of the bonding surface using an Ar ion beam in a non-oxidizing atmosphere, and then further cleaned the surface of the bonding surface. By forming and bonding a bonding alloy layer such as copper using vapor deposition or sputter vapor deposition, it is possible to achieve strong laminated bonding at relatively low temperatures and bonding pressures, without fear of deformation. This is what we found out.
Another method for laminated bonding is brazing, but when using this method, the amount of brazing filler metal must be carefully controlled as there is a risk that the filler metal may flow into the fluid passage and block it during bonding. be. Another method is to perform liquid phase diffusion bonding by inserting an insert into the joint surface, but even with this method, there is a risk that the passage may be filled by penetration of the insert, so careful attention must be paid to the thickness of the insert. There is.

In contrast, in the present invention, the bonding alloy layer is formed by vapor deposition or sputter vapor deposition, so the thickness of the alloy layer can be made extremely thin, and even if the bonding alloy melts during bonding, it will not flow into the passage. Laminated structure cooling fins with precise fluid passages can be easily manufactured without any problems.

Even in the case of a structure in which ceramic is interposed between metal, a thin metallized layer is formed on the ceramic bonding surface by vapor deposition or sputter deposition, and a bonding alloy layer is further formed. It is exactly the same as in the case of comrades.

In addition, in the method of manufacturing a laminated structure cooling fin, after cleaning the bonding surfaces of the thin plates in a non-oxidizing atmosphere and forming a bonding alloy layer on the bonding surfaces, grooves that will become fluid passages during bonding are processed. There is no problem with that.

[Embodiments of the invention]

Embodiments of the present invention are illustrated in FIGS. 1, 2, and 3.
This will be explained using figures.

Two aluminum thin plates 9 with a thickness of 2 mm shown in Fig. 1 are punched out using a press so as to form a fluid passage 5 as a narrow slot and a fluid passage 11 as a wide slot when stacked. Four thin plates 10 and two 4 mm-thick aluminum plates 6, which were similarly press-punched to form fluid passages 13 as enlarged slots, were prepared, and these were charged into a vacuum chamber. Ar on each joint surface
After cleaning by irradiating with an ion beam, copper was deposited to a thickness of 0.5 μm by sputter deposition in the same vacuum chamber. After the aluminum plates subjected to the above treatment were stacked as shown in Fig. 2, they were loaded into a vacuum furnace.
Bonding was performed at 450° C. for 1 hour under a pressure of 0.5 Kg/mm ² to integrate the respective plates and produce a cooling fin as shown by the solid line in FIG. In the cooling fin shown in FIG. 3, after each thin plate is joined as described above, holes are made for the inflow and outflow ports for the cooling medium and the fluid passages 5 and 11 are connected so that the cooling medium can flow into each fluid passage. In order to do this, holes are drilled from the side surface 12, and connection pipes 7 and 8 are provided at the medium inflow and outflow ports for circulating the cooling medium between the cooling fins and the condenser.
are integrated by welding. FIG. 4 shows a sectional view taken along the line AA shown in FIG. In this embodiment, the fluid passages 11 and 13 are provided in advance, but this is to facilitate the subsequent drilling process, and it is not necessarily necessary to provide the fluid passages 11 and 13 in advance. The fluid passages 11 and 13 may be formed so as to be connected to the fluid passage 5 during later drilling. Further, although two busbars are used, this is also to facilitate punching, and there is no essential problem even if only one busbar is used.

The cooling fin of this example has a rectangular fluid passage measuring 5 mm x 6 mm, and as a result of measuring its thermal resistance, it was found to be an extremely excellent cooling fin of 0.005°C/W. . It also has excellent airtightness, at less than 10 ^-9 Torr/sec, and is approximately 1/2 thinner than conventional cooling fins.

〔Effect of the invention〕

According to the present invention, a method for manufacturing a laminated structure cooling fin for a semiconductor is provided in which a plurality of narrow slot holes are formed in parallel corresponding to one semiconductor element, and wide slots are formed near the beginning and end of each of the narrow slot holes. The formed thin plate and another thin plate in which enlarged slots with a width extending from the wide slot of this thin plate to the end of the narrow slot are formed at positions corresponding to the ends of the wide slot and the narrow slot are made into two flat plates. By placing an appropriate number of sheets between them, stacking them and bonding them together, if necessary, the slotted holes can be made finer and fluid passages on the micron order of 100 μm or less can be freely formed, resulting in high cooling efficiency. It is possible to realize a semiconductor cooling fin that can accommodate the miniaturization of equipment, and since wide slots and enlarged slots are pre-formed in the thin plate, the inlet and outlet holes leading to the narrow slots can be easily made. It has the effect that it can be processed.

[Brief explanation of drawings]

Figure 1 is a diagram showing the shape of the laminate of the present invention, Figure 2 is a diagram showing the shape of the laminate of the present invention.
The figure is a schematic diagram of the lamination state of the present invention, Figure 3 is a completed diagram of the cooling fin according to the present invention, Figure 4 is a sectional view of the cooling fin of Figure 3, Figure 5 is a schematic diagram of the boiling cooling device, FIG. 6 is a diagram showing the manufacturing process of a conventional cooling fin, FIG. 7 is a diagram showing a completed conventional cooling fin, and FIG. 8 is a diagram showing a hollow cooling fin. DESCRIPTION OF SYMBOLS 1... Cooling fin, 2... Condenser, 3... Insulating material, 4... Semiconductor element, 5, 11, 13... Fluid passage, 6... Bus bar, 7, 8... Condenser and cooling fin Connection pipe, 9...Thin plate for installing semiconductor elements,
10... Thin plate for fluid passage formation, 12... Side surface.

Claims (1)

[Claims] 1. A method for producing a cooling fin with a laminated structure for a semiconductor, which is formed by laminating thin metal plates with good thermal conductivity and has a fluid passage inside for cooling a semiconductor element attached to an outer surface, wherein the thin plate is a flat plate. a first thin plate, a plurality of narrow slot holes are formed in parallel corresponding to one semiconductor element, and wide grooves are formed in the vicinity of each of the starting and ending ends of the plurality of narrow slot holes, orthogonal to the narrow slot holes. a second thin plate having a hole formed therein; and an enlarged slot having a width extending from the wide slot formed in the second thin plate to include the end of each narrow slot, corresponding to the wide slot and the end of the narrow slot. We manufactured three types with a third thin plate formed at the position where
The bonding surfaces of each of the thin plates are cleaned in a non-oxidizing atmosphere to form a bonding alloy layer on the bonding surfaces, and then one first thin plate, one or more second thin plates,
One or more third thin plates, one or more second thin plates, and one first thin plate are laminated and bonded in this order, and an enlarged longitudinal slot is formed from one side of the bonded laminated plates. A cooling fin with a laminated structure for semiconductors, characterized in that an inlet hole and an outlet hole are formed in the direction so that the wide slot of the second thin plate and each narrow slot are directly connected, and each groove is used as a passage for fluid. manufacturing method.