JPS63193534A - Semiconductor stack apparatus - Google Patents

Abstract

PURPOSE:To prevent deterioration of the characteristics of a semiconductor element, by providing covers between cooling fins and the semiconductor element, forming the covers each in a cap shape so as to cover the end parts of the cooling fins on the sides of the element, and blocking the intrusion of moisture to the contact surfaces of the cooling fins on the sides of the element. CONSTITUTION:Fin protecting covers 21 and 22 are provided between cooling fins 7 and 8 and electrodes 1a and 1b of a semiconductor element 1. The covers 21 and 22 are formed respectively in a cap shape so as to cover the end parts of the fins 7 and 8 on the sides of the element. The covers 21 and 22 are formed with thin plates comprising the same material as those of the electrodes 1a and 1b. Intrusion of moisture to contact surfaces 7a and 8a of the fins 7 and 8 on the sides of the element is blocked with the covers 21 and 22. Thus the deterioration of the characteristics of the semiconductor element 1 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor stack device equipped with cooling fins made of aluminum.

[Conventional technology]

In general, semiconductor stack devices are known that are equipped with cooling fins that effectively dissipate heat in order to stabilize the operation of semiconductor elements.

Conventionally, this type of semiconductor stack device has been constructed as shown in FIG. To explain this based on the same figure,
In the figure, reference numeral 1 denotes a semiconductor element which is held under pressure between two holding plates 3 and 4 through which four tightening bolts 2 are inserted, and has copper electrodes 1a and 1b on its upper and lower surfaces, and 5 and 6 refer to this semiconductor element. Output terminals 7 and 8 provided between the semiconductor element 1 and the holding plate 3.4 are aluminum cooling fins provided between these output terminals 5, 6 and the semiconductor element 1. These cooling fins 7.8 and the output terminals 5, 6 are positioned on the semiconductor element side and the holding plate side, respectively. Further, 9 and 10 are the holding plates 3.
4 and the output terminal 5°6;
Reference numeral 1 designates a nut into which the tightening bolt 2 is screwed. In addition,
The pressing plate 3.4 is formed of an elastic metal body.

[Problem that the invention seeks to solve]

By the way, in this type of semiconductor stack device, 2
When a current flows between the two output terminals 5.6 via the semiconductor element 1 and the cooling fins 7.8, a potential difference is generated at the contact surface A between the semiconductor element 1 and the cooling fins 7.8 due to the contact resistance. When a semiconductor stack device is cooled by forced air, moisture contained in the cooling air infiltrates between the two members, forming a local battery on the contact surface A, and the cooling fins 7.8 become metal ionized. Therefore, electrolytic corrosion phenomenon may occur in these parts. For this reason, the contact resistance between the semiconductor element 1 and the cooling fins 7.8 increases, and the cooling performance of the cooling fins 7.8 deteriorates.As a result, the characteristics of the semiconductor element 1 deteriorate and the operational reliability of the device decreases. There was a problem with the decline.

Therefore, in the conventional semiconductor stack device, cooling fins 7
．． A special surface treatment called so-called copperizing has been applied to the surface of No. 8 on the semiconductor element side, but this method has the disadvantage of increasing manufacturing costs.

The present invention has been devised in view of these circumstances, and it is an object of the present invention to provide a semiconductor stack device that not only can improve the operational reliability of the device but also can be manufactured at low cost.

[Means for solving problems]

In the semiconductor stack device according to the present invention, a cover made of the same material as the electrode of the semiconductor element is interposed between the cooling fin and the semiconductor element, and this cover is formed in a cap shape to cover the element side end of the cooling fin. This is what is being done.

[For production]

In the present invention, the cover can prevent moisture from entering the element-side contact surface of the cooling fin.

〔Example〕

FIG. 1 is a front view showing a semiconductor stacking device according to the present invention, and FIGS. 2(a) and 2(b) are a plan view and a sectional view showing a cover of the semiconductor stacking device, which are the same as FIG. 3. The same reference numerals are given to the members, and detailed description thereof will be omitted. In the same figure, numerals 21 and 22 indicate covers for protecting the cooling fins 7.8.
The cooling fin 7.8 is interposed between the electrodes 1a and 1b of the semiconductor element 1, and the entire cooling fin 7.8 is formed into a cap shape that covers the element-side end of the cooling fin 7.8. Further, these covers 21 and 22 are formed of thin plates made of the same material as the electrodes 1a and lb.

In the semiconductor stack device configured in this way,
The cover 21.22 can prevent moisture from entering the element side contact surfaces 7a, 8a of the recooling fins 7.8.

Therefore, when a semiconductor stack device is cooled by forced air, the contact surface of the cooling fins 7.8 on the element side? It is extremely unlikely that a battery will be formed in a and 8a.

Incidentally, the heat generated by energizing the semiconductor element 1 is absorbed by the cover 2.
1.22 from the cooling fins 7.8. In this case, the electrodes la, lb and the cover 21.22 are made of copper material, and the cover 21.22
Since the cooling fins 7 and 7 are thin plates, the thermal conductivity between the semiconductor element 1 and the cooling fins 7 and 8 is extremely good.
．． The cooling performance of No. 8 does not deteriorate.

Here, even if a potential difference occurs due to contact resistance between the electrodes 1a, 'lb and the cover 21, 22, a battery will not be formed on the contact surface, so that electrolytic corrosion phenomenon will occur in both members. There is no.

In this embodiment, even if electrolytic corrosion occurs due to the battery formed between the cover 21.22 and the cooling fins 7.8, this effect will not affect the semiconductor element 1.
There is no need to replace the semiconductor element 1 over a long period of time,
Maintenance costs can be reduced accordingly.

〔Effect of the invention〕

As explained above, according to the present invention, a cover made of the same material as the electrodes of the semiconductor element is interposed between the cooling fin and the semiconductor element, and this cover has a cap shape that covers the element side end of the cooling fin. Therefore, the cover can prevent moisture from entering the element-side contact surface of the cooling fin.

Therefore, unlike in the conventional case, the cooling fins do not undergo electrolytic corrosion, so deterioration of the characteristics of the semiconductor element can be prevented, and the operational reliability of the device can be improved.

Further, since there is no need to perform special surface treatment on the cooling fins as in the conventional case, the cooling fins can be manufactured at extremely low cost.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a semiconductor stack device according to the present invention, FIGS. It is a front view showing.■...Semiconductor element, la, lb...electrode, 2.
... Tightening bolt, 3, 4... Holding plate, 5, 6...
...Output terminal, 7,8...Cooling fin, 21.2
2...Cover. Agent Masuo Oiwa 1 Figure 2 (a) (b)

Claims (1)

[Claims] A semiconductor element which is held under pressure between two holding plates through which a tightening bolt is inserted and has electrodes on both sides thereof, an output terminal provided between the semiconductor element and the holding plate, and this output terminal and the semiconductor element. A cover made of the same material as the electrode is interposed between the cooling fin and the semiconductor element, and the cover is arranged between the cooling fin and the semiconductor element. A semiconductor stack device characterized in that it is formed in a cap shape that covers a side end portion.