JPH11150219A - Package for semiconductor integrated element, and mounting thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be able to maintain a high reliability even under harsh thermal cyclings. SOLUTION: A connecting substrate 11 is combinedly connected with a heat sink 21 by means of set screws 22, 22,.... Even when the heat sink 21 is tightened by means of the set screws 22, 22,..., the heat sink can accommodate a difference in thermal expansion coefficient between the heat sink 21 and substrate 11, whereby there is no possibility that an excessive stress occurs in the substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated device package capable of maintaining a high degree of reliability even under a severe heat cycle in which heating and cooling are repeated, and a method of mounting the same.

[0002]

2. Description of the Related Art When a semiconductor integrated device is mounted on a motherboard including a printed circuit board, a dedicated package is sometimes used.

[0003] The package is formed by integrating a heat sink made of metal having good heat conductivity and a connection board made of ceramics having good insulating properties by means such as brazing. An opening is formed in the center of the connection board. In order to solve this problem, a semiconductor integrated device is fixed to a heat sink through an opening, and each electrode of the semiconductor integrated device is drawn out to a connection electrode on a connection substrate.
A package can be formed, and each connection electrode can be mounted on the motherboard by soldering to a pattern electrode on the motherboard.

[0004]

According to the prior art, since the connection board is integrated with a radiator plate having a different coefficient of thermal expansion, if the connection board is subjected to a severe heat cycle of repeated heating and cooling, Excessive stress may be generated due to the difference in thermal expansion with the heat sink, which may cause warpage, cracks, or disconnection from the motherboard by soldering, which significantly reduces the operational reliability of the semiconductor integrated device. There was a problem that would.

In view of the above-mentioned problems of the prior art, an object of the present invention is to maintain a high degree of reliability even under a severe heat cycle by attaching a heat sink to a connection board via a set screw. It is an object of the present invention to provide a package for a semiconductor integrated device that can be used and a mounting method thereof.

[0006]

According to a first aspect of the present invention, an opening is formed at a central portion, a connecting substrate having a connecting electrode on a back surface, and a set screw are provided. The gist of the present invention is to fix a semiconductor integrated device to the heat sink through an opening through the heat sink.

The set screw can have a screw thread whose apex angle is asymmetric, and can be prevented from loosening via an adhesive.

In the connection substrate, a step is formed around the opening, and an auxiliary electrode connected to each connection electrode can be drawn out to the step.

Further, the connection board may seal the semiconductor integrated element on the heat sink through the opening, and an adhesive may be interposed between the heat sink and the connection board.

A second aspect of the invention has a gist that, when the package according to the first aspect is mounted on a motherboard, the head of a set screw is soldered to a fixed electrode of the motherboard.

[0011]

According to the first aspect of the present invention, the radiator plate is attached to the connection board via the set screw, but is not completely integrated with the connection board. In other words, the radiator plate can effectively absorb the difference in thermal expansion with the connection board even when the axial force due to the tightening torque of the set screw is operating, so that excessive stress is applied to the connection board. There is no risk of generating. However, the mounting hole of each set screw is formed to have a necessary and sufficient diameter so as to absorb a difference in thermal expansion between the heat sink and the connection board. In addition, an aluminum plate, a copper plate, or an alloy plate of these can be used as the heat radiating plate, and a glass epoxy resin, ceramics, or the like can be used as the connection substrate.

A set screw having a screw thread whose apex angle is asymmetric can prevent loosening by plastically deforming the screw thread of the screw hole when screwed into the screw hole of the heat sink, and is loosened carelessly by a heat cycle. There is no fear.

[0013] If the set screw is prevented from being loosened via the adhesive, the set screw can be more securely prevented from being loosened. Note that the set screw at this time may have a symmetrical or asymmetrical thread angle.

When the step is formed around the opening of the connection substrate, it can be adapted to a semiconductor integrated device having a higher integration degree. This is because an auxiliary electrode can be arranged at each step in the step. Each auxiliary electrode is
It is assumed that the electrodes are electrically connected to the electrodes of the semiconductor integrated element on the heat sink by wire bonding or the like and are drawn out to the corresponding connection electrodes.

When the semiconductor integrated device on the heat sink is sealed through the opening, the connection substrate can mechanically and effectively protect the semiconductor integrated device and connection wires drawn from the semiconductor integrated device. The sealing method at this time is as follows:
Either resin sealing in which an epoxy resin or the like is filled in the opening or can-type sealing in which a metal cap is attached to the opening may be used.

The heat sink can further increase the connection strength with the connection board by interposing an adhesive between the connection boards. However, the adhesive at this time preferably has an appropriate elasticity in order to absorb a difference in thermal expansion between the heat sink and the connection board.

According to the configuration of the second aspect, the set screw can form a predetermined gap between the connection board and the motherboard via the head thereof. Therefore, even when dissolving the solder balls and soldering the connection electrodes of the connection board and the pattern electrodes of the motherboard, there is no possibility that the solder balls will be crushed by the weight of the package, and the connection between the connection electrodes and the pattern electrodes will not occur. Since an appropriate distance can be secured, the stress due to the difference in thermal expansion between the package and the motherboard can be reduced, and the reliability of the solder joint between the two can be greatly improved. Note that heat generated on the package side can be released to the motherboard side via the set screw, which can contribute to preventing the set screw itself from being loosened.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

The package PA for a semiconductor integrated device comprises a connection board 11 and a heat sink 21 attached to the front side of the connection board 11 via set screws 22, 22.
(Fig. 2). However, in FIG. 1, the package PA is shown upside down.

The connection board 11 is made of a high-performance insulating material such as glass epoxy resin or ceramics and has a thickness of about 1 mm.
It is formed in a plate-like shape. A rectangular opening 11a is formed at the center of the connection board 11, and mounting holes 11b for the set screws 22 are formed at the four corners. The connection substrate 11 has stepped steps 11c, 11c formed on the back side around the opening 11a, and a number of connection electrodes 12, outside the openings 11a, the steps 11c, 11c. 12 are arranged in an orderly manner. .. Are arranged in each step 11c. Each of the auxiliary electrodes 13 is electrically connected to a specific connection electrode 12 via a connection pattern (not shown) embedded in the connection substrate 11. Connected. That is, auxiliary electrodes 13, 13... That are individually connected to the respective connection electrodes 12 are drawn out from each step portion 11c.

The heat radiating plate 21 is an aluminum plate or a copper plate of the same size as the connection substrate 11, and has four mounting holes 11 at the four corners.
Screw holes 21 for set screws 22 corresponding to b, 11b,.
are formed. Therefore, the heat sink 21
Are attached to the front surface side of the connection board 11 via set screws 22, 22. The heat sink 21 has an opening 1.
The semiconductor integrated device DV is fixed via 1a. In the semiconductor integrated device DV, a predetermined electrode can be connected to a predetermined auxiliary electrode 13 via a connection wire W such as a gold wire or an aluminum wire by wire bonding, and the predetermined electrode can be drawn out to a predetermined connection electrode 12. . The connection substrate 11 can seal the semiconductor integrated device DV through the opening 11a by filling the opening 11a with a filler A such as an epoxy resin.

Each set screw 22 has a head portion 22a and a screw portion 22b (FIG. 3). The diameter d1 of each mounting hole 11b on the connection board 11 side is
The clearance δ is set to have a sufficiently large clearance δ with respect to the maximum diameter of b. On the other hand, the screw portion 2 of the set screw 22
2b is formed with a thread in which the thread angles θ1 and θ2 are asymmetric (FIG. 4). Therefore, the set screw 22 has a peak angle θ1
When the screw portion 22b is screwed into the screw hole 21b on the side of the heat radiating plate 21 having a symmetrical angle θ1, the screw thread on the angle θ2 <θ1 causes a part of the female screw of the screw hole 21b to be plastically deformed, The thread closely contacts the thread of the internal thread,
It can be effectively locked. However, the screw portion 22
The maximum diameter of b is slightly larger than the effective diameter of the female screw in the screw hole 21b.

Package PA for such a semiconductor integrated device
Can be mounted on the motherboard PB together with the semiconductor integrated device DV (FIGS. 2 and 3).

That is, the connection board 11 connects each connection electrode 12 to the pattern electrode PB1 on the motherboard PB via the solder H, and the head 2 of each set screw 22
By connecting 2a to the fixed electrode PB2 on the motherboard PB, it can be mounted on the motherboard PB. At this time, the connection board 11 has a predetermined gap D between the connection board 11 and the motherboard PB via the head 22a of each set screw 22.
Is formed, and the quality of soldering between each connection electrode 12 and the pattern electrode PB1 by melting the solder ball H1 can be appropriately maintained. Solder ball H
This is because there is no possibility that the package 1 and the motherboard PB are crushed, and stress caused by a difference in thermal expansion between the package PA and the motherboard PB can be reduced.

The heat radiation plate 21 is fastened to the connection board 11 via set screws 22, 22..., But there is a clearance δ between the mounting hole 11b and the screw portion 22b of the set screw 22. Therefore, the screw 22 can be expanded and contracted in the radial direction within the range of the clearance δ.
Therefore, there is no possibility that the package PA will generate an excessive stress on the connection board 11 due to a difference in thermal expansion between the radiator plate 21 and the connection board 11 even under a heat cycle.

In the above description, each set screw 22
In order to solder the head 22a to the fixed electrode PB2 of the motherboard PB, it is preferable to perform a solder plating finish. However, the soldering of each set screw 22 to the head 22a and the fixed electrode PB2 can be omitted.

[0027]

[Other Embodiments] An adhesive S may be interposed between the heat sink 21 and the connection board 11 (FIG. 5). Adhesive S
Is preferably a resin-based adhesive having appropriate elasticity. The radiator plate 21 can expand and contract via the adhesive S without generating excessive stress on the connection substrate 11.

In the above description, each set screw 22
The screw hole 21b may be loosened with an adhesive (not shown). At this time, the set screw 22 may have an asymmetrical or symmetrical ridge angle θ1, θ2.

[0029]

As described above, according to the first aspect of the present invention, the connection board is provided with the heat sink on the front side of the connection board via the set screw, so that the expansion of the heat sink is improved. There is no danger of excessive stress due to shrinkage, so even under severe heat cycles,
There is an excellent effect that a high degree of reliability can be maintained.

According to the second invention, the head of the set screw for attaching the heat sink to the connection board is soldered to the fixed electrode of the motherboard, so that the solder between the connection electrode of the connection board and the pattern electrode of the motherboard is soldered. In addition to improving the reliability of bonding, there is an effect that the heat radiation effect of the package is enhanced and the set screw itself can be prevented from loosening.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of the entire configuration.

FIG. 2 is an enlarged sectional explanatory view of a main part of FIG. 1;

FIG. 3 is an enlarged view of a main part of FIG. 2;

FIG. 4 is an enlarged view of a main part of FIG. 3;

FIG. 5 is a diagram corresponding to FIG. 3, showing another embodiment.

[Explanation of symbols]

 PA: Package PB: Mother board PB2: Fixed electrode DV: Semiconductor integrated element S: Adhesive θ1, θ2: Crest angle 11: Connection board 11a: Opening 11c: Step 12: Connection electrode 13: Auxiliary electrode 21: Heat sink 22 … Set screw 22a… Head

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Aoki Federation 383 Aiki-cho, Matsuto-shi, Ishikawa Prefecture Nikko Corporation

Claims (7)

[Claims] 1. A connection board having an opening formed in a central portion and having a connection electrode on the back side, and a heat radiating plate attached to the front side of the connection board via a set screw, wherein the heat radiating plate includes A package for the semiconductor integrated device, wherein the semiconductor integrated device is fixed through the opening. 2. The package for a semiconductor integrated device according to claim 1, wherein said set screw has a screw thread whose apex angle is asymmetric. 3. The package for a semiconductor integrated device according to claim 1, wherein said set screw is provided with a locking agent via an adhesive. 4. The connection substrate according to claim 1, wherein the connection substrate has a step formed around the opening, and an auxiliary electrode connected to each of the connection electrodes is led out to the step. A package for a semiconductor integrated device according to any one of the above. 5. The semiconductor integrated device according to claim 1, wherein the connection substrate seals the semiconductor integrated device on the heat sink through the opening. package. 6. An apparatus according to claim 1, wherein an adhesive is interposed between said heat radiating plate and said connection board.
The package for a semiconductor integrated device according to any one of the above. 7. When mounting the package according to claim 1 on a motherboard, the head of the set screw is soldered to a fixed electrode of the motherboard. Package implementation method.