JPH05267486A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve reliability and quality by making a thickness of adhesive between a cap and an IC chip fixed. CONSTITUTION:A sealing height adjusting frame 21 having an opening which an IC chip 1 faces is interposed between a wiring substrate 2 and an opening edge part of a cap 9. A cap guide 23 whereto the cap 9 fits is provided to project from the sealing height adjusting frame 21. An interval between the IC chip 1 and the cap 9 changes by moving the cap 9 vertically along the cap guide 23. Therefore, it is possible to adhere the IC chip and the cap by adhesive of a fixed thin thickness, to improve cooling efficiency and to easily remove void in the adhesive.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device in which an IC chip is covered with a hermetically sealing cap.

[0002]

2. Description of the Related Art As a conventional semiconductor device of this type, there is one having a structure as shown in FIG. FIG. 7 is a cross-sectional view showing a conventional semiconductor device. The semiconductor device shown in FIG.
E TRANSACTIONS. (VOL.E 74, NO.8 AUGUST 1991) P.233
It was published in 3.

In FIG. 7, 1 is TAB (Tape Automat).
ed Bonding) IC chip, and this IC chip 1 is mounted face down on the wiring board 2. In addition, 3 shows a TAB lead. Reference numeral 4 is a silicon rubber interposed between the IC chip 1 and the wiring board 2.

Reference numeral 5 is a cap for hermetically sealing the IC chip 1. The opening edge of the cap 5 is seam welded to the wiring board 2 side. In addition, this cap 5
The inner bottom portion of is bonded to the upper surface of the IC chip 1.

In this semiconductor device, the silicon rubber 4 is interposed as a cushioning material between the IC chip 1 and the wiring board 2 due to variations in the height dimension and the inclination of the IC chip mounted on the wiring board 2. It was absorbed by letting it.

In the semiconductor device shown in FIG. 7, the IC chip 1 is connected to the wiring board 2 via the TAB lead 3. However, a semiconductor device in which the IC chip is mounted face down has a structure as shown in FIG. Some have been made.

FIG. 8 is an enlarged sectional view showing a part of a conventional semiconductor device of flip chip mounting type. The semiconductor device shown in FIG. 8 is the 41st ECTC paper collection, 1991.
It was published on P.704. In FIG.
The same or similar members as those described in 1 are assigned the same reference numerals and detailed description thereof will be omitted. In the semiconductor device shown in FIG. 8, the IC chip 1 is connected to the pads 8 on the thin film 7 provided on the wiring board 2 by the solder bumps 6.

Then, the AlN cap 9 is soldered to the wiring board 2 via the solder 10 to form the IC chip 1
Is hermetically sealed. In this semiconductor device, the variation in the AIN cap 9 and the variation in the mounting height of the IC chip 1 are absorbed by the AIN cap 9 being selected after mounting the IC chip 1 or by the solder thickness.

[0009]

In the conventional semiconductor device shown in FIG. 7, the adhesive thickness between the cap 5 and the IC chip 1 is made constant by using the silicon rubber 4, but recent IC chips have been used. With the increase in the number of signals in the IC chip, flip chip mounting in which signals are taken out from the entire surface of the IC chip via bumps or I / O via minute pins for input / output.
In the micro-pin mounting that picks up signals from the entire surface of the C chip, it becomes impossible to protect the connection portion from the lower surface of the IC chip with an elastic body such as silicon rubber.

Such a problem is caused by the I
The bonding thickness between the cap 9 and the IC chip 1 may be made constant by selecting the cap 9 after mounting the C chip. However, in the structure in which the cap 9 is selected and the height is adjusted after the IC chip 1 is attached as shown in FIG.
Since a plurality of types of caps 9 must be formed, there is a problem that cost and yield are deteriorated.

If the cap height and the IC chip mounting height are not adjusted, the wiring board 2 shown in FIG.
The variation of the height H to the inner bottom (inner wall) of is ± 0.0
Since the height h from the wiring board 2 to the upper surface of the IC chip 1 mounted face down is ± 0.05 mm, the thickness of the adhesive 11 for bonding the IC chip 1 and the cap 9 is about 3 mm. If the minimum thickness is 0.03 mm, it will vary from 0.03 to 0.21 mm. In addition,
FIG. 9 is an enlarged cross-sectional view showing a part of a conventional semiconductor device when the size of the cap is not changed.

As the adhesive 11 becomes thicker, the heat source I
There is a problem that the thermal resistance from the C chip 1 to the upper surface of the cap 9 which is the heat radiation surface increases, and the cooling effect decreases. Further, when the adhesive 11 becomes thick, it becomes difficult to remove voids in the adhesive 11, and there is a problem that reliability and quality are poor, such as an increase in thermal resistance and the occurrence of cracks due to thermal stress.

Further, if solder is used to bond the cap 9 and the IC chip 1, the solder may be scattered on the signal leads or the wiring substrate 2 at the time of bonding, or the solder may be melted by heating at the time of repair, so that the IC chip may be melted. There is a possibility that the connecting portion between the wiring board 1 and the wiring board 2 may be short-circuited.

[0014]

A semiconductor device according to a first aspect of the present invention provides an IC between a wiring board and an opening edge portion of a cap.
A frame body having an opening facing the chip is interposed, and a guide extending in a direction away from the wiring board and fitted with the cap is provided on the frame body.

A semiconductor device according to a second aspect of the present invention is the semiconductor device according to the first aspect of the present invention, wherein the guide is provided with a partition plate that faces the inside of the opening of the frame and is close to the side surface of the IC chip.

[0016]

In the semiconductor device according to the first aspect of the present invention, by moving the cap up and down along the guide of the frame body,
The distance between the C tip and the cap changes.

In the semiconductor device according to the second aspect of the present invention, the bonding portion between the IC chip and the cap is isolated from the IC chip mounting portion by the partition plate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to FIG. FIG. 1 is a cross-sectional view of a semiconductor device according to the present invention. In FIG. 1, the same or equivalent members as those described in FIGS. 7 to 9 are designated by the same reference numerals and detailed description thereof will be omitted.

The semiconductor device shown in FIG. 1 has a TAB lead 3
Is connected to the pad 8 formed on the wiring board 2 by a gold-gold thermocompression bonding method, so that the IC chip 1 is mounted face down on the wiring board 2. The IC chip 1 is sealed by a cap 9 and a sealing height adjusting frame 21 described later. The wiring board 2 is provided with bumps 6 for connecting the semiconductor device to a board or the like (not shown).

Reference numeral 21 is a sealing height adjusting frame as a frame body for supporting the cap 9. In this embodiment, the sealing height adjusting frame 21 is made of alumina ceramics and has a square shape in plan view.
And the cap guide 23 on the inner peripheral side are formed in an L-shaped cross section. Further, the opening width of the sealing height adjusting frame 21 is set to such a size that the IC chip 1, the TAB lead 3 and the like can be exposed in the opening.

The cap guide 23, which is rectangular in plan view, extends in a direction away from the wiring board 2 and is formed with an outer diameter dimension so that the cap 9 can be fitted to the outside thereof.

The sealing height adjusting frame 21 is joined to the wiring board 2 via the sealing material 24 with the IC chip 1 and the like facing the opening.

As the material of the sealing height adjusting frame 21, other than the above-mentioned materials, for example, AIN, SiC, Kovar, Cu / W alloy or the like can be used. Also,
As the sealing material 24, an epoxy resin agent, Sn / Pb
Various brazing materials such as solder, Au / Sn, Au / Si, Au / Ge, and Ag brazing are used.

The opening edge of the cap 9 is sealed with the sealing material 25 on the cap adhesive flange 22 of the sealing height adjusting frame 21.
And the inner bottom is adhesively bonded.
It is adhered to the upper surface (back surface) of the IC chip 1 via. When the cap 9 is joined to the sealing height adjusting frame 21, the cap guide 23 of the sealing height adjusting frame 21 is fitted into the opening of the cap 9.

As the encapsulating material 25, the same encapsulating material 24 in which the encapsulating height adjusting frame 21 is joined to the wiring board 2 can be used, but the material is changed depending on the joining conditions such as equipment. It doesn't matter. For example, 80Au / 20S
n solder or the like can also be adopted. Further, as the adhesive 26, one having high thermal conductivity is adopted. For example, Epotek B9028 manufactured by Epotek Co., Sn / Pb solder paste or the like is thinly applied by a method such as printing with a template and a fixed amount is supplied to bond.

That is, the cap 9 is sealed and the height adjusting frame 2 is closed.
In the state where the cap 9 is fitted and attached to the No. 1, the cap 9 is movable in the height direction along the cap guide 23. Therefore, even if the mounting height from the wiring board 2 to the upper surface of the IC chip 1 or the height of the cap 9 varies, the cap 9
The cap 9 can be surely sealed and joined to the sealing height adjustment frame 21 at a position where the inner bottom surface of the cap 9 comes into close contact with the upper surface of the IC chip 1 via the adhesive 26.

For example, the mounting height of the IC chip 1 from the wiring board 2 is 0.8 ± 0.05 mm, and the height from the opening edge of the cap 9 to the inner bottom surface is 0.3 ± 0.05 mm.
The sealing height adjustment frame 21 has a thickness of 0.2 ± 0.05 mm, a height of 0.4 ± 0.05 mm, and the sealing materials 24 and 25 have a thickness of 0.01 to
If the thickness is 0.05 mm, the height of the inner bottom surface of the cap 9 can be moved within the range of 0.55 to 1.0 mm at worst, and the thickness of the adhesive 26 is selected within the range of 0 to 0.15 mm. Depending on the method of supplying the adhesive 26,
Bonding with an accuracy of 01 ± 0.005 mm is possible.

Therefore, since the gap between the IC chip 1 and the cap 9 is changed by moving the cap 9 up and down along the cap guide 23 of the sealing height adjusting frame 21, only one type of cap 9 is formed. Also, the thickness of the adhesive 26 can be set to a predetermined thickness.

In this embodiment, the TAB connection is performed to mount the IC chip 1 face down on the wiring board 2. However, as shown in FIGS. 2 and 3, the flip chip connection method is used. It is also possible to adopt the micropin connection method.

FIG. 2 is a sectional view showing another embodiment in which an IC chip is mounted by the flip-chip connection method of the semiconductor device according to the first invention, and FIG. 3 is a micropin connection of the semiconductor device according to the first invention. It is sectional drawing which shows the other Example in which the IC chip was mounted by the method. In these figures, the same or equivalent members as those described in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

The semiconductor device shown in FIG. 2 has an IC chip 1
High temperature solder bump 31 (for example, 10Sn / 90Pb,
80Au / 20Sn), and the high temperature solder bumps 31 are bonded to the pads 8 on the wiring board 2 to mount the IC chip 1 on the wiring board. Then, the cap 9 is joined to the wiring board 2 via the sealing height adjustment frame 21. In addition, the wiring board 2 has a structure shown in FIG.
Micro pins 32 are provided instead of the bumps 6 shown in FIG.

The semiconductor device shown in FIG. 3 has an IC chip 1
A micro lead pin (hereinafter referred to as a micro pin) 33 is provided in the IC chip 1, and the lower end of the micro pin 33 is bonded to the pad 8 on the wiring board 2 to mount the IC chip 1 on the wiring board 2. Micro pin 3
The lower end of 3 is high temperature solder (eg 10Sn / 90Pb, 8
0Au / 20Sn or the like) to the pad 8, and the upper end of the micro pin 33 has a higher temperature solder (for example, C
d / Ag, Zn / Al, etc.) to the pad 1a of the IC chip 1. Then, the cap 9 is joined to the wiring board 2 via the sealing height adjustment frame 21.
Further, the wiring board 2 is provided with gull wing-shaped leads 34 instead of the bumps 6 shown in FIG.

2 and 3, the same effect as that of the embodiment shown in FIG. 1 can be obtained. The bumps 6, the micro pins 32, and the gull-wing leads 34 provided on the wiring board 2 may be combined in any manner.

In the TAB mounting method and the micro pin connection method described above, the TAB leads and the micro pins alleviate the thermal stress due to the difference in thermal expansion between the IC chip 1 and the wiring board 2, so that the wiring board 2 is made of, for example, alumina. It is possible to use a material having a coefficient of thermal expansion different from that of silicon such as ceramics. In the flip chip mounting method using solder bumps, it is necessary to select a material based on the thermal expansion coefficient depending on the size of the IC chip 1.

Next, the semiconductor device according to the second invention is shown in FIG.
Will be described in detail by. FIG. 4 is a cross-sectional view of a semiconductor device according to the second invention. In the figure, the same or equivalent members as those described in FIG. 1 above are given the same reference numerals and detailed description thereof is omitted.

In FIG. 4, 41 is a sealing height adjusting frame 21.
The partition plate 41 is integrally provided with the partition plate 41. The partition plate 41 extends from the tip end portion of the cap guide 23 in the sealing height adjustment frame 21 into the opening. That is, the sealing height adjustment frame 21 is formed in a stepwise cross section by the cap adhesive flange 22, the cap guide 23, and the partition plate 41. And, as the protruding size of the partition plate 41,
The dimensions are set such that the protruding end is close to the side surface of the IC chip 1 located in the opening.

When this sealing height adjusting frame 21 is bonded onto the wiring board 2 on which the IC chip 1 is mounted, the partition plates 41 are brought close to the four side surfaces of the IC chip 1 and the lateral space of the IC chip 1 is partitioned. It will be defined vertically by the plate 41.

When the cap 9 is joined to the sealing height adjusting frame 21, the inner bottom surface of the cap 9 and the IC
When an electrically conductive adhesive having a low viscosity (for example, Sn / Pb solder or the like) is used as the adhesive 26 for adhering the upper surface of the chip 1, the adhesive 26 scatters at the time of adhesion (for example, the adhesive 26 Can be prevented from entering the joint between the IC chip 1 and the wiring board 2 by flow (for example, when an epoxy adhesive having an Ag filler is used as the adhesive 26). ..

Therefore, since the bonding portion between the IC chip 1 and the cap 9 is isolated from the IC chip 1 mounting portion by the partition plate 41, the adhesive 26 scatters or flows to the IC chip mounting portion. Intrusion can be prevented.

In the embodiment shown in FIG. 4, in order to mount the IC chip 1 on the wiring board 2 face down, T
Although the example in which the AB connection is performed is shown, as shown in FIGS. 5 and 6, the flip chip connection method or the micropin connection method can also be adopted.

FIG. 5 is a sectional view showing another embodiment in which an IC chip is mounted by the flip-chip connection method of the semiconductor device according to the second invention, and FIG. 6 is a micropin connection of the semiconductor device according to the second invention. It is sectional drawing which shows the other Example in which the IC chip was mounted by the method. In these figures, the same or equivalent members as those described in FIGS. 1 to 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

The semiconductor device shown in FIG. 5 has an IC chip 1
The high-temperature solder bumps 31 are provided on the IC chip 1 and the IC chips 1 are mounted on the wiring board by bonding the high-temperature solder bumps 31 to the pads 8 on the wiring board 2. Then, the cap 9 is joined to the wiring board 2 via the sealing height adjustment frame 21. Further, the wiring board 2 is provided with micro pins 32 instead of the bumps 6 shown in FIG.

The semiconductor device shown in FIG. 6 has an IC chip 1
The micro pin 33 is provided in the
The IC chip 1 is mounted on the wiring board 2 by bonding the lower end of the to the pad 8 on the wiring board 2.
Then, the cap 9 is joined to the wiring board 2 via the sealing height adjustment frame 21. Further, the wiring board 2 is provided with gull wing-shaped leads 34 instead of the bumps 6 shown in FIG.

Even if it is constructed as shown in FIGS. 5 and 6, the same effect as that of the embodiment described in FIG. 4 can be obtained.

[0045]

As described above, in the semiconductor device according to the first aspect of the invention, between the wiring board and the opening edge of the cap,
The frame body having an opening facing the IC chip is interposed,
A guide, which extends in a direction away from the wiring board and into which the cap fits, is provided on the frame body. Therefore, by moving the cap up and down along the guide of the frame body, the distance between the IC chip and the cap is increased. Will change.

Therefore, even if the mounting height of the IC chip and the height of the cap vary, it is possible to bond the IC chip and the cap with a thin adhesive of a constant thickness.
Therefore, the thermal resistance from the IC chip to the upper surface of the cap can be lowered, the cooling efficiency can be improved, and the voids in the adhesive can be easily removed, so that the reliability and quality of the semiconductor device can be improved. ..

A semiconductor device according to a second aspect of the present invention is the semiconductor device of the first aspect, in which the guide is provided with a partition plate that faces the inside of the opening of the frame and is close to the side surface of the IC chip.
The part where the IC chip and the cap are bonded is separated by a partition plate.
It is isolated from the C chip mounting part.

Therefore, it is possible to prevent the adhesive for bonding the IC chip and the cap from entering the IC chip mounting portion, so that the reliability and quality are improved and
The product yield can be improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductor device according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment in which an IC chip is mounted by the flip-chip connection method of the semiconductor device according to the first invention.

FIG. 3 is a cross-sectional view showing another embodiment in which an IC chip is mounted by the micropin connection method for a semiconductor device according to the first invention.

FIG. 4 is a sectional view of a semiconductor device according to a second invention.

FIG. 5 is a cross-sectional view showing another embodiment in which an IC chip is mounted by the flip-chip connection method for a semiconductor device according to the second invention.

FIG. 6 is a sectional view showing another embodiment in which an IC chip is mounted by the micropin connection method for a semiconductor device according to the second invention.

FIG. 7 is a cross-sectional view showing a conventional semiconductor device.

FIG. 8 is an enlarged sectional view showing a part of a conventional semiconductor device of a flip chip mounting system.

FIG. 9 is an enlarged cross-sectional view showing a part of a conventional semiconductor device when the size of the cap is not changed.

[Explanation of symbols]

 1 IC Chip 2 Wiring Board 9 Cap 21 Sealing Height Adjustment Frame 23 Cap Guide 26 Adhesive 41 Partition Plate

Claims (2)

[Claims] 1. An IC chip is mounted face-down on a wiring board, and an IC is capped with an airtight sealing cap whose opening edge is joined to the wiring board side and whose inner bottom is joined to an LSI chip. In the above semiconductor device, a frame body having an opening facing the IC chip is interposed between the wiring board and the opening edge portion of the cap, and the frame body is provided in a direction away from the wiring board. A semiconductor device, characterized in that a guide that extends and fits the cap is projected. 2. The semiconductor device according to claim 1, wherein the guide is provided with a partition plate which faces the inside of the opening of the frame and is close to the side surface of the IC chip.