JP2630083B2 - Semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power semiconductor device such as a power module, and more particularly to a structure of an outer case for sealing a semiconductor element with a resin.

[0002]

2. Description of the Related Art In a conventional power module, a flexible resin such as silicon gel and a hard resin such as an epoxy resin are filled into an outer case in which a semiconductor element is built in layers in a vertical direction. Some semiconductor devices are encapsulated by the method. This will be described with reference to FIG. FIG. 2 is a sectional view of a conventional semiconductor device. In FIG. 1, reference numeral 1 denotes a diode module as a conventional semiconductor device. This diode module 1 is configured by connecting two diode chips in series. Reference numeral 2 denotes an outer case of the diode module 1. The outer case 2 includes a frame portion 2a and a bottom plate portion 2b. A copper base plate 3 for mounting a diode chip is fixed to a bottom portion, and a lid is provided on an upper portion. The body 4 is fixed. On the copper base plate 3, an insulating substrate 5 made of ceramic, an anode terminal 6, an anode molybdenum plate 7
The diode chip 8 is mounted via the like. Further, a cathode copper electrode 10 is connected to the diode chip 8 via a cathode molybdenum plate 9. In this diode module 1, two diode chips 8 are mounted on the left and right sides in the figure. An anode terminal 6 connected to the left diode chip 8 has one end protruding upward through the lid 4 and the other end connected to the right side. It is connected to the cathode copper electrode 10 for the diode chip. Further, a cathode terminal 10a is connected to the cathode copper electrode 10 for the diode chip on the left side, and the cathode terminal 10a penetrates through the lid 4 and protrudes upward. Further, the anode terminal 6 for the right diode chip also protrudes upward through the cover 4. 11 is a flexible resin made of silicone gel, 12
Is a hard resin made of epoxy resin, and the diode chip 8 is sealed with these resins. The flexible resin 11 is filled in the surrounding case 2 in such an amount that the diode chip 8 is buried therein.
Is filled on the flexible resin 11 in the outer case 2. That is, the flexible resin 11 and the hard resin 1
2 means that the upper and lower layers are filled in layers.

In order to assemble the conventional diode module 1 constructed as described above, first, a copper base plate 3 on which a diode chip 8, terminals and the like are mounted is surrounded by an outer case 2.
To the bottom. Next, the outer case 2 is filled with the flexible resin 11 by a predetermined amount. Then, after the soft resin 11 is cured, the outer case 2 is filled with the hard resin 12. In this case, the terminals protruding outside the outer case penetrate the hard resin 12 up and down. After the hard resin 12 is hardened, the lid 4 is fixed on the outer case 2 and the protruding end of each terminal is bent to complete the assembling operation.
When the hard resin 12 is cured, each terminal is bonded to the hard resin 12.

[0004]

However, the conventional diode module 1 configured as described above has a problem that its life is shortened. This is because the flexible resin 11 whose thermal expansion coefficient is about 50 times that of the hard resin 12 is sealed by the hard resin 12 and the outer case 2. That is, this diode module 1
When the temperature of the entire case rises due to energization, the soft resin 11 thermally expands and the internal pressure increases, so that a force is applied to the hard resin 12 to push it up. Then, the cathode copper electrode 10 and the cathode terminal 10a integral with the hard resin 12 are pulled in a direction away from the diode chip 8, and the solder for bonding the diode chip is quickly fatigued. In order to solve such a problem, the flexible resin 11 may be configured not to be sealed as shown in FIG. FIG. 3 is a cross-sectional view showing a conventional semiconductor device in which a flexible resin is communicated with the atmosphere. FIG. 3 shows the semiconductor device disclosed in Japanese Patent Application Laid-Open No. 2-222565. In FIG. 3, the same or equivalent members as those described in FIG. 2 are denoted by the same reference numerals, and detailed description is omitted. In the semiconductor device shown in FIG. 3, partition plates 13, 13 located between the terminal arrangement portion and the side wall of the outer case 2 are integrally provided in the outer case 2. A pressure relief recess 14 is provided between the partition plate 13 and the outer case 2. The plurality of recesses 14 are provided in one outer case 2, and the inside of each recess 14 is communicated with the outside of the device through an air vent hole 15 formed so as to penetrate the upper wall of the outer case 2. I have. The hard resin 12 is filled between the partition plates 13. That is, in the semiconductor device configured as described above,
This prevents the flexible resin 11 from being hermetically sealed and increasing the internal pressure due to thermal expansion. However, in this semiconductor device, since it is necessary to provide the air vent hole 15 for each pressure relief portion (recess portion 14), there is a problem that a planar chip which is easily affected by the outside and is relatively sensitive to humidity cannot be employed. .

[0005]

A semiconductor device according to the present invention is provided with a cover for covering a resin filling portion in an outer case, and at a position inside the outer case surrounding the semiconductor element mounting portion. The lower end is buried in the flexible resin and the upper end is
A partition with a communicating part is provided in the section
Filling the hard resin below the communication section
The inside and outside of the outer case are communicated with the lid so as to face the
It has a vent hole .

[0006]

The pressure relief portions are provided on both sides of the semiconductor element mounting portion, and these pressure relief portions are
It is communicated via a communicating portion between the hard resin and the lid.
For this reason, all the pressure relief parts are communicated outside the device through the air vent holes.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIG. FIG. 1 is a sectional view showing a semiconductor device according to the present invention. In FIG. 1, the same or equivalent members as those described in FIGS. 2 and 3 are denoted by the same reference numerals, and detailed description is omitted. In FIG. 1, reference numeral 21 denotes a partition wall for forming a pressure relief portion inside the outer case 2, and two partition walls 21 in the present embodiment are formed in parallel with each other inside the frame-shaped outer case 2. And is provided integrally with the surrounding case 2. The partition 21 is disposed on the side of the terminal or the like so as to surround the semiconductor element mounting portion. Further, the height (width) of the partition 21 is shorter than the height of the side wall of the outer case 2, and when the copper base plate 3 and the cover 4 are attached to the outer case 2, And a gap is formed on the lower side. In other words, by providing the partition 21 in the outer case 2, the side walls are provided on both left and right sides of the outer case 2 so that the space between the double walls is a pressure relief portion in this embodiment. 22. Reference numeral 23 denotes an air vent hole. The air vent hole 23 is formed in the upper surface and the lower surface of the lid 4 and is formed so as to penetrate the lid 4. I have.

Next, a procedure for assembling a semiconductor device using the surrounding case 2 provided with the partition walls 21 will be described. First, the insulating substrate 5 is fixed on the copper base plate 3 with solder, and the anode terminal 6 and the anode molybdenum plate 7 are fixed thereon in that order. Further, a diode chip 8, a cathode molybdenum plate 9, a cathode copper electrode 10 and the like are sequentially soldered on the anode molybdenum plate 7, and a cathode terminal 10a is connected to the cathode copper electrode 10 connected to the left diode chip 8. Also, one end of the anode terminal 6 connected to the left diode chip 8 is connected to the cathode copper electrode 10 connected to the right diode chip 8. Next, the copper base plate 3 on which the diode chip 8 and the like are mounted is fixed to the bottom of the outer case 2, and the diode chip mounting portion is housed in the outer case 2. Then, a predetermined amount of soft resin 11 made of silicone gel is filled in the outer case 2 (to the extent that the diode chip 8 is buried) and cured. At this time, the flexible resin 11 flows into the double wall through the gap below the partition 21. Further, the portion surrounded by the partition 21 is filled with a hard resin 12 made of epoxy resin and cured. By doing so, the flexible resin 11 is exposed in the pressure relief portion 22. After that, the cover 4 is fixed to the outer case 2 and the end of each terminal is bent to complete the assembling operation. When the lid 4 is attached, a gap is provided between the lid 4 and the hard resin 12, and the left and right pressure relief portions 22 communicate with each other through the gap. Become. The gap communicates with the outside of the device through the air vent hole 23.

In the thus assembled diode module, when the temperature rises and the flexible resin 11 thermally expands, the pressure due to the expansion is applied to the pressure relief portion 22 by the flexible resin 1.
1 can escape by flowing. For this reason, since the force for pushing up the hard resin 12 does not act on the hard resin 12, the solder does not become fatigued at an early stage. Further, the pressure relief portions 22 on both sides of the diode chip mounting portion are provided.
The two are communicated via a space between the hard resin 12 and the lid 4. Therefore, all the pressure relief portions 22 are communicated to the outside of the device through the air vent holes 23, and only one air vent hole 23 can be provided, so that moisture hardly enters from outside the device. When a durability test was performed using the semiconductor device according to the present invention, it was found that the intermittent current-carrying life was five times or more that of the conventional semiconductor device.

In this embodiment, the diode module has been described. However, it goes without saying that the present invention can be applied to all power devices having a structure sealed with resin.

[0011]

As described above, in the semiconductor device according to the present invention, the outer case is provided with the lid for covering the resin filling portion, and is provided inside the outer case at a position surrounding the semiconductor element mounting portion. , the upper and lower ends are embedded in the flexible resin
A partition provided with a communication portion at the end is provided inside the partition.
A hard resin is filled below the communication portion, and the hard resin is filled.
Communicate the inside and outside of the outer case with the lid so as to face the fat
Since the air vent holes are formed , pressure relief portions are provided on both sides of the semiconductor element mounting portion, and these pressure relief portions are communicating portions between the hard resin and the lid. > Is communicated through. For this reason, all the pressure relief portions are communicated with the outside of the device through the air vent holes, and only one air vent hole can be provided. Therefore, it is difficult for moisture to enter from outside the device and to be less affected by the outside,
A semiconductor device having a long power cycle life and high reliability can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor device according to the present invention.

FIG. 2 is a cross-sectional view of a conventional semiconductor device.

FIG. 3 is a cross-sectional view showing a conventional semiconductor device in which a flexible resin is communicated with the atmosphere.

[Explanation of symbols]

 2 Surrounding case 4 Lid 6 Anode terminal 8 Diode chip 10a Cathode terminal 11 Flexible resin 12 Hard resin 21 Partition wall 23 Vent hole

Claims (1)

(57) [Claims] 1. An external connection terminal in which a flexible resin for sealing a semiconductor element and a hard resin are filled up and down in a layered manner with the flexible resin on a lower side in an outer case. In the semiconductor device, which penetrates the hard resin and protrudes out of the outer case, a cover for covering the resin filling portion is provided in the outer case, and a semiconductor element mounting portion inside the outer case is provided. A partition wall with a lower end buried in a flexible resin and a communication section at the upper end
The hard tree is located below the communication part inside the mound partition wall.
Grease and fill the lid so as to face this hard resin.
A semiconductor device having an air vent hole communicating with the inside and outside of an outer case .