JP4678941B2 - Composite semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite semiconductor device that suppresses the amount of warping of a heat sink after basing and after a change with time.
[0002]
[Prior art]
A schematic structure of this type of composite semiconductor device is shown in FIG.
In the figure, reference numeral 1 denotes the entire composite semiconductor device, and this composite semiconductor device 1 has a heat sink 2 on its bottom surface. An insulating substrate 3 is soldered onto the heat radiating plate 2 with solder 9, and electronic components such as a semiconductor pellet 4 and an external lead-out terminal 5 are mounted and fixed on the insulating substrate 3. The other end of the external lead-out terminal 5 is drawn out through the through hole 7 of the lid body 6.
[0003]
By the way, as shown in FIG. 5, the semiconductor pellet 4 is soldered onto the conductive pattern 3a of the insulating substrate 3 on the upper surface of the heat radiating plate 2. However, the metallized layer (not shown) on the lower surface of the insulating substrate 3 The plate 2 is also soldered by the solder 9 as described above.
[0004]
In this case, when the insulating substrate 3 made of a ceramic substrate such as Al2O3 or AlN and the heat radiating plate 2 made of copper are soldered, warpage occurs due to the difference in thermal expansion between the two. As shown in FIG. 5, the warp is generated in such a manner that the central portion of the lower surface of the heat radiating plate 2 is concave (convex upward).
[0005]
The composite semiconductor device 1 shown in FIG. 3 is assembled in the above state. And when it attaches to another member, for example, a radiation fin, using the mounting hole which illustration of the heat sink 3 was abbreviate | omitted, a clearance gap will be formed between the heat sink 3 and a radiation fin, and the heat dissipation effect will worsen.
[0006]
In order to improve the above point, conventionally, when the heat radiating plate 2 is manufactured, as shown in FIG. 4, the center portion 2a of the lower surface is made convex in advance to control the warpage amount S1.
Furthermore, the warpage amount S2 (see FIG. 5) immediately after the insulating substrate 3 is soldered to the heat sink 2 is reduced if left for several days, and finally, as shown in FIG. The central portion 2a of the heat radiating plate 2 changes to a convex shape and is stabilized at the warp amount S3. Considering this, conventionally, the amount of warpage S1 in the reverse direction is first determined and set when manufacturing the heat sink 2 so that the amount of warpage S3 of the heat sink 2 in the finished product is minimized.
[0007]
[Problems to be solved by the invention]
However, the above treatment has the following problems.
That is, after soldering the insulating substrate 3 to the heat sink 2, warping of 100 μm or more is reversed and added. There is a first inversion at the time of basing from the initial state of the convex shape below the heat sink 2, a concave shape at the bottom, and a second inversion that warps downward due to changes over time. Due to this inversion, mechanical stress is applied to the insulating substrate 3, which may adversely affect the semiconductor pellet 4 on the insulating substrate 3 and may deteriorate the characteristics of the composite semiconductor device 1.
[0008]
OBJECT OF THE INVENTION
The present invention has been made to solve the above-described problems. The final warpage amount S3 of the heat sink is reduced, and the change amount of the warpage is relatively reduced so that cracks in the insulating substrate and semiconductor pellets are obtained. An object of the present invention is to provide a composite semiconductor device in which the adverse effects of the above are prevented.
[0009]
[Means for Solving the Problems]
The composite semiconductor device of the present invention is a composite semiconductor device having an insulating substrate on which electronic components such as semiconductor pellets are placed by soldering on a heat sink.
The heat radiating plate is provided with a slit or the like for reducing the amount of warpage of the heat radiating plate itself.
[0010]
[Action]
In the composite semiconductor device of the present invention, since the slit is formed at the adjacent position where the insulating substrate of the heat sink is placed and fixed, the stress applied at the time of basing and change with time is relieved by the slit, and until the initial state is restored. The amount of change in warpage is reduced. For this reason, adverse effects such as cracking of the insulating substrate and mechanical stress applied to the semiconductor pellet can be minimized.
[0011]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view of a heat sink used in the composite semiconductor device of the present invention, and FIG. 2 is a vertical cross-sectional view of a state in which an insulating substrate is placed and fixed on the heat sink.
In these figures, 12 is a heat sink made of a copper material.
In this example, a plate having a thickness of 5 mm and dimensions of 186 mm × 93 mm was used.
[0012]
As seen in FIGS. 1 and 2, the slits 20 at a plurality of positions of the heat radiating plate 12, provided so as to penetrate through the heat radiating plate 12 at about the width dimension of the insulating substrate 13. The position of the slit 20 is between the insulating substrates 13 and 13 adjacent to each other. In this example, the dimension of the slit 20 was 5 mm × 70 mm. The dimension of the insulating substrate 13 was 50 mm × 70 mm. A plurality of mounting holes 21 for mounting to an external member such as a heat radiating fin are provided on the outer peripheral portion of the heat radiating plate 12.
[0013]
Next, the heat radiating plate 12 is subjected to pre-bending with a press machine or the like so as to have a downward convex shape of S1 (see FIG. 4) = 100 μm.
Next, the insulating substrate 13 is placed on and fixed to the heat radiating plate 12 via the solder 9, and the semiconductor pellet 4 is fixed to the insulating substrate 13 by soldering in the same manner as in FIG. By this basing process, the heat sink 12 warps downwardly in a concave shape as shown in FIG.
[0014]
However, the warpage amount S2 is alleviated by the formation of the slit 20, and in the case of the above embodiment, S2 is about 1 mm.
Thereafter, the heat radiating plate 12 was allowed to stand in a natural environment for 48 hours, and a change with time was observed. As a result, it was warped downward like FIG. 6, but S3 = about 0.3 mm.
[0015]
When the above phenomenon is analyzed, the outline is as follows.
That is, the heat sink 12 after the basing process is recessed downward, and at that time, residual stress exists in the solder layer that is the connection portion between the insulating substrate 13 and the heat sink 12. The residual stress is erased with time due to the sliding phenomenon of the solder, and finally returns to the shape at the time of pre-bending and warps downward, but by forming the slit 20, the stress at the time of the first basing, and thereafter It is considered that the stress at the time of the change with time is alleviated and the amount of warpage decreases.
[0016]
The heat radiating plate 12 is fixed to one opening end of the insulating case 10 having both end openings shown in FIG. In this case, when the inside of the insulating case 10 is filled with a gel-like substance or the like, a sealing member (not shown) that closes the slit 20 formed in the heat radiating plate 12 is provided to the outside of the insulating case 10. It is possible to prevent the spilled material and the like from flowing out.
[0017]
【The invention's effect】
As described above, according to the present invention, since the slit penetrating the heat sink having the width of the insulating substrate is provided at a predetermined position of the heat sink, the amount of warp of the heat sink generated in the manufacturing process of the composite semiconductor device is insulated. It can be made relatively small corresponding to the width of the substrate. Therefore, there is an effect that it is possible to effectively reduce cracking of the insulating substrate placed / fixed on the heat sink and mechanical stress applied to the semiconductor pellet placed / fixed on the insulating substrate.
[Brief description of the drawings]
FIG. 1 is a plan view of a heat sink used in a composite semiconductor device of the present invention.
FIG. 2 is a longitudinal sectional view of the heat radiating plate.
FIG. 3 is a longitudinal sectional view showing a schematic structure of a conventional composite semiconductor device.
FIG. 4 is a side view of a pre-bended insulating plate used in the composite semiconductor device.
FIG. 5 is a side view of the insulating substrate after a basing process in which the insulating substrate is placed and fixed.
FIG. 6 is a side view of the insulating substrate after change with time.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Composite semiconductor device 9 Solder 12 Heat sink 13 Insulating substrate 20 Slit 21 Mounting hole

Claims (3)

In the composite semiconductor device having an insulating substrate on which an electronic component such as a semiconductor pellet is mounted by soldering to the heat radiating plate, to the heat radiating plate, a slit for reducing the warpage amount of the heat sink itself, of the insulating substrate A composite semiconductor device characterized in that it is provided between insulating substrates adjacent to each other so as to penetrate a heat sink with a width of about.   2. The composite semiconductor device according to claim 1, wherein the slit is formed at a plurality of locations of the heat sink across a region where the insulating substrate is disposed.   The composite semiconductor device according to claim 1, further comprising a closing member that closes the slit.

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