JP3189270B2 - Bonding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding method and a semiconductor device, and more particularly, to a bonding method of bonding a heat sink to a printed board on which a semiconductor chip is mounted, and a semiconductor device using the bonding method.

[0002]

2. Description of the Related Art A semiconductor device having a conventional tape-ball grid array (BGA) structure is described in Japanese Patent Application Laid-Open No. 8-51128 (first conventional example). FIG. 5 is a cross-sectional view showing a semiconductor device described in this publication, and FIG. 6 is a perspective view showing a joining process between a heat spreader and a stiffener. As shown in FIG. 5, the semiconductor device has a TAB (Tape Automate) connected to a mounting substrate having a predetermined wiring pattern via solder balls 26.
d Bonding) tape 22, a semiconductor chip 21 mounted on the TAB tape 22 via conductive leads of the TAB tape 22, and a heat spreader 28 facing the TAB tape 22. On the back surface (land surface) of the TAB tape 22, a plurality of solder balls 26 are joined in a matrix.

In the above-described semiconductor device, the TAB tape 22 and the heat spreader 28 have rectangular shapes corresponding to each other, and an insulating material is provided in a state where the semiconductor chip 21 is positioned in a through hole formed in a central portion of the TAB tape 22. It is sealed with a resin 25. A stiffener 23 having a shape surrounding the semiconductor chip 21 on the TAB tape 22 is provided between the TAB tape 22 and the heat spreader 28, and the stiffener 23 is fixed to the TAB tape 22 with an adhesive 24. As shown in FIG. 6, the heat spreader 28 is bonded to the semiconductor chip 21 by a silicone-based elastomer liquid adhesive 27 applied to the back surface (upper surface) of the semiconductor chip 21 and the upper surface of the stiffener 23, respectively.
And stiffeners 23 respectively.

Another semiconductor device having a Tape-BGA structure is disclosed in Japanese Patent Application Laid-Open No. 9-8186 (second conventional example). FIG. 7 is a perspective view showing a method for manufacturing the semiconductor device described in this publication. In this semiconductor device, in order to prevent warpage of the LSI package (PKG) to be manufactured, the upper surface of the heat spreader 28 in FIG.
A thermosetting adhesive 20 is applied to the lower surface of the semiconductor chip 21 which is mounted on a TAB tape (not shown) and is located at the center of the stiffener 23, respectively, and the stiffener 23 and the semiconductor chip 21 are fixed to the heat spreader 28.

[0005]

In the first conventional example, the semiconductor chip 21 and the heat spreader 28, and both the stiffener 23 and the heat spreader 28 are fixed to each other by using only the liquid adhesive 27. When the liquid adhesive 27 is used, the effect of preventing the package from being warped or deformed is obtained. However, in order to prevent the two positions from shifting after the heat spreader 28 is attached to the stiffener 23, the package is fixed with a special jig. A complicated process such as not giving vibration is required. Moreover, the liquid adhesive 2
After curing of 7, the heat spreader 28 may be displaced due to heat shrinkage during curing. In order to fix the heat spreader 28 with the liquid adhesive 27, a step of pressing the heat spreader 28 toward the semiconductor chip 21 and the stiffener 23 is required.
In some cases, the distance between the heat spreader 28 and the heat spreader 28 is not stable.

In the second conventional example, since the stiffener 23 and the heat spreader 28 are fixed with the thermosetting adhesive 20, the heat spreader 28 with respect to the stiffener 23 is fixed.
, The adhesive strength of the thermosetting adhesive 20 is too strong, so that the stiffener 23 and the heat spreader 28 may be deformed when thermally expanded, and the product may be broken by stress. Also, stiffener 23
The deformation of the solder ball changes the height of the solder ball, causing variations in coplanarity. At the time of mounting, the solder ball does not come into contact with the solder paste applied to the mounting board, and an open defect may occur.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a bonding method capable of avoiding deformation due to thermal expansion and assembling a package in a favorable state by a simple process, and a semiconductor device using the bonding method. And

[0008]

According to a first aspect of the present invention, there is provided a bonding method for bonding a heat sink to a printed circuit board on which a semiconductor chip is mounted. And a step of alternately arranging and setting a thermosetting adhesive and a thermoplastic adhesive on the bonding surface of the printed circuit board, and bonding the heat sink and the printed circuit board to each other in the bonding step. Wherein the thermosetting adhesive is attached to two mutually opposing corners of the printed circuit board, and the thermoplastic adhesive is attached to two mutually opposing corners of the heat sink. .

The "printed board" in the present invention comprises a printed board and a reinforcing member fixed on the printed board.

In the bonding method according to the present invention, when the heat sink is attached to the printed board, the thermosetting adhesive is cured while the heat sink is positioned on the printed board with a thermoplastic adhesive. Can be completely fixed. For this reason, the displacement between the heat sink and the printed circuit board is avoided,
The thermosetting adhesive can prevent the heat sink from warping or deforming. Therefore, it is possible to avoid the conventional problem that the heat sink is displaced due to the heat shrinkage of the adhesive, and it is possible to omit a complicated process such as fixing with a dedicated jig to prevent the heat sink or the like from being displaced. Further, it is possible to eliminate such a problem that the heat sink is inclined with respect to the printed board or the distance between the heat sink and the printed board is not stable. Furthermore, the heat sink and the printed circuit board have mutually corresponding square shapes, and a thermosetting adhesive is attached to the two opposite corners of the printed circuit board, and the heat is applied to the two opposite corners of the heat sink. Since the plastic adhesive is adhered, the heat radiating plate can be accurately positioned on the printed circuit board, and the heat radiating plate can be completely fixed to the printed circuit board by curing the thermosetting adhesive in this state.

[0011]

[0012] The bonding method (second invention) of the present invention is a bonding method for bonding a heat sink to a printed board on which a semiconductor chip is mounted. A step of alternately arranging and bonding plastic adhesives, wherein in the bonding step, the heat radiating plate and the printed board have a rectangular shape corresponding to each other, and the thermosetting is performed at each corner of the printed board. A thermoplastic adhesive is attached, and the thermoplastic adhesive is attached to a central portion of each side of the heat sink. Book second
According to the invention, the same effect as that of the first invention is obtained, and the heat sink and the printed board have a square shape corresponding to each other, and a thermosetting adhesive is attached to each corner of the printed board, and the heat dissipation is performed. Since the thermoplastic adhesive is attached to the center of each side of the board, the thermoplastic adhesive is located at the center of each side of the heat sink, which suppresses the displacement of the heat sink and the printed board and heat sink. Is further improved.

The bonding method (third invention) of the present invention is a bonding method for bonding a heat sink to a printed board on which a semiconductor chip is mounted, wherein a thermosetting adhesive and a thermosetting adhesive are applied to the bonding surface between the heat sink and the printed board. A step of alternately arranging and bonding plastic adhesives, and in the bonding step, the heat radiating plate and the printed board have a square shape corresponding to each other, and the central portion of each side of the printed board is A thermosetting adhesive is attached, and the thermoplastic adhesive is attached to each corner of the heat sink. Book 3
According to the invention, the same effect as that of the first invention can be obtained, and the heat sink and the printed board have a square shape corresponding to each other, and a thermosetting adhesive is attached to the center portion of each side of the printed board. Since the thermoplastic adhesive is attached to each corner of the heat sink, the semiconductor chip located in the internal space formed by the heat sink and the printed board is sealed well by the thermosetting adhesive and the thermoplastic adhesive. Can be stopped. In this case, the presence of the thermoplastic adhesive at the four corners of the radiator plate can further improve the effect of suppressing the displacement of the radiator plate and the effect of suppressing the inclination of the radiator plate.

Specifically, the thermosetting adhesive is composed of a silicone-based elastomer liquid adhesive having thermal conductivity. In this case, heat generated in the semiconductor chip can be efficiently transmitted to the heat radiating plate and radiated. Also,
Specifically, the adhesive surface of the printed board is constituted by the surface of a reinforcing member fixed to the printed board.

[0015]

[0016]

[0017]

The present invention will be described in more detail with reference to the drawings. FIG. 1 is a sectional view showing a semiconductor device having a Tape-BGA structure according to a first embodiment of the present invention. The semiconductor device is connected to a TAB tape (printed board) 12 connected to a mounting board having a predetermined wiring pattern via a solder ball 16 via a conductive lead (ILB: Inner Lead Bond) of the TAB tape 12. TA
A semiconductor chip 11 mounted on a B tape 12 and a TAB
Heat spreader (radiator plate) 18 facing tape 12
And On the land on the back of the TAB tape 12,
A plurality of solder balls 16 for outputting signals from the semiconductor chip 11 to the outside are joined in a matrix.

TAB tape 12 and heat spreader 1
8 has a mutually corresponding square shape, and the TAB tape 1
The semiconductor chip 11 is inserted into a through hole formed in the center of the semiconductor chip 11.
Are sealed with the insulating resin 15 in a state where the are positioned. A stiffener (reinforcing member) 13 having a square shape corresponding to the heat spreader 18 and surrounding the semiconductor chip 11 on the TAB tape 12 is provided between the TAB tape 12 and the heat spreader 18.
The stiffener 13 is fixed to the TAB tape 12 with an adhesive 14. The adhesive 14 suppresses warpage of the TAB tape 12 and the like.

The heat spreader 18 includes an adhesive 19 adhered to the back surface (FIG. 2) and a silicone-based elastomer liquid adhesive (thermosetting adhesive) applied to the back surface of the semiconductor chip 11 and the upper surface of the stiffener 13, respectively. 17 to the semiconductor chip 11 and the stiffener 13, respectively. The adhesive 19 constitutes a thermoplastic adhesive that does not cure when heat is applied, and can be attached to the heat spreader 18 as an adhesive tape applied to a tape in advance. The elastomer liquid adhesive 17 has elasticity and good heat dissipation, can reduce stress at the time of adhesion and at the time of adhesion, and further efficiently transmits heat generated in the semiconductor chip 11 to the heat spreader 18 to release heat. Improve characteristics.

FIG. 2 is a perspective view showing a step of joining the heat spreader and the stiffener. First, TAB tape 1
2, a stiffener 13 is fixed in the vicinity of the peripheral edge of the TAB tape 12 with an adhesive 14, and then an elastomer liquid is adhered to two opposite corners of the stiffener 13 and the back surface of the semiconductor chip 11. Each of the agents 17 is applied.

Next, an adhesive 19 is applied to the two corners of the heat spreader 18 facing each other and the vicinity thereof. At this time, the two corners to which the adhesive 19 is adhered are portions that do not face the two corners of the stiffener 13 where the elastomer liquid adhesive 17 is applied and the vicinity thereof, and the total length of the adhesive 19 at the two corners is Preferably, it corresponds to the length of the portion where the elastomer liquid adhesive 17 is not applied. Further, the heat spreader 18
To the stiffener 13 with good positional accuracy and paste
The heat spreader 18 is easily fixed with the adhesive 19, and in this state, the semiconductor device is heated at a predetermined temperature using an oven. At this time, the thermoplastic adhesive 19 does not cure,
Only the elastomer liquid adhesive 17 is thermally cured to completely fix the heat spreader 18.

Therefore, in this embodiment, since the displacement between the heat spreader 18 and the stiffener 13 due to vibration, heat shrinkage of the adhesive or the like can be avoided, a special jig for preventing the displacement of the heat spreader 18 and the like can be avoided. It is possible to omit a complicated process such as fixing by using. Further, the deformation when the stiffener 13 and the heat spreader 18 thermally expand is absorbed by the adhesive 19 and the liquid adhesive 17, and the liquid adhesive 17 after curing can prevent the heat spreader 18 from warping or deforming. Further, it is possible to solve problems such as the inclination of the heat spreader 18 or the unstable distance between the heat spreader 18 and the stiffener 13.

Further, in the present embodiment, the conventional problems such as the adhesive strength of the adhesive being too strong, causing deformation of the stiffener 13 and the heat spreader 18 which thermally expand, and applying stress to the package to cause product breakage. Can be eliminated. Furthermore, it is possible to avoid such a problem that the solder ball 16 does not come into contact with the solder paste applied to the mounting board (not shown) and an open defect occurs. Further, the semiconductor chip 11 located in the internal space formed by the heat spreader 18, the stiffener 13 and the TAB tape 12 can be reliably sealed by the elastomer liquid adhesive 17 and the adhesive 19.

Next, a second embodiment of the present invention will be described. FIG. 3 is a perspective view for explaining the assembling process of the embodiment. In the present embodiment, the stiffener 13 and the heat spreader 18 are used similarly to the first embodiment.
Have quadrangular shapes corresponding to each other, and the assembling process is almost the same as that of the first embodiment, but the positions where the elastomer liquid adhesive 17 and the adhesive 19 are attached are different.

In this embodiment, an elastomer liquid adhesive 17 is applied to the four corners of the stiffener 13 and the vicinity thereof, and an adhesive 19 is applied to the center of each side of the heat spreader 18. In this case, the portion where the adhesive 19 is adhered is the stiffener 13
It is a portion that does not face the portion where the elastomer liquid adhesive 17 is applied, and the length of each attached portion of the adhesive 19 preferably corresponds to the length of the portion where the elastomer liquid adhesive 17 is not applied.

In the above embodiment, the same effects as those of the first embodiment can be obtained, and the adhesive 19 is located at the center of each side of the heat spreader 18. The suppression effect and the effect of suppressing the inclination between the stiffener 13 and the heat spreader 18 are further improved as compared with the first embodiment.

Next, a third embodiment of the present invention will be described. FIG. 4 is a perspective view for explaining the assembling process of the embodiment. Also in this embodiment, the stiffener 13 and the heat spreader 18 have square shapes corresponding to each other as in the first embodiment, and the assembling process is almost the same as in the first embodiment. The attachment positions of the adhesive 17 and the adhesive 19 are different.

In the present embodiment, an elastomer liquid adhesive 17 is applied to the central portion of each side of the stiffener 13 and its vicinity, and an adhesive 19 is applied to each corner of the heat spreader 18. in this case,
The portion where the adhesive 19 is adhered is a portion that does not face the portion of the stiffener 13 where the elastomer liquid adhesive 17 is applied, and the length of each adhered portion of the adhesive 19 is the portion where the elastomer liquid adhesive 17 is not applied. Preferably corresponds to the length of

In the present embodiment described above, the same effects as in the first embodiment can be obtained, and since the adhesive 19 is present at the four corners of the heat spreader 18, the displacement of the heat spreader 18 is suppressed. The effect is second
It is further improved than in the embodiment. Further, in the present embodiment, the liquid adhesive 17 is cured and completely fixed in a state where the four corners of the heat spreader 18 and the stiffener 13 are simply fixed, so that the effect of suppressing the inclination between the stiffener 13 and the heat spreader 18 is also improved. Further improve.

Although the present invention has been described based on the preferred embodiment, the bonding method and the semiconductor device of the present invention are not limited only to the configuration of the above-described embodiment. The bonding method and the semiconductor device obtained by making various modifications and changes from the configuration described above are also included in the scope of the present invention.

[0031]

As described above, according to the bonding method and the semiconductor device of the present invention, it is possible to avoid deformation due to thermal expansion and to assemble the package in a favorable state by simple steps.

[Brief description of the drawings]

FIG. 1 shows a Tape-B according to a first embodiment of the present invention.
It is sectional drawing which shows the semiconductor device of GA structure.

FIG. 2 is a perspective view for explaining an assembling process in the first embodiment.

FIG. 3 is a perspective view for explaining an assembling process according to a second embodiment of the present invention.

FIG. 4 is a perspective view for explaining an assembling process according to a third embodiment of the present invention.

FIG. 5 is a sectional view showing a conventional semiconductor device.

FIG. 6 is a perspective view illustrating a process of assembling a conventional semiconductor device.

FIG. 7 is a perspective view for explaining another assembly process of a conventional semiconductor device.

[Explanation of symbols]

 11: Semiconductor chip 12: TAB tape (printed circuit board) 13: Stiffener (reinforcing member) 14: Adhesive 15: Insulating resin 16: Solder ball 17: Elastomer liquid adhesive (thermosetting adhesive) 18: Heat spreader (Heat dissipation) Board) 19: Adhesive (thermoplastic adhesive)

Claims (5)

(57) [Claims] 1. A bonding method for bonding a heat sink to a printed board on which a semiconductor chip is mounted, wherein a thermosetting adhesive and a thermoplastic adhesive are alternately disposed on the bonding surface of the heat sink and the printed board. In the bonding step, the heat radiating plate and the printed board have a square shape corresponding to each other, and the thermosetting adhesive is attached to two mutually facing corners of the printed board, The bonding method, wherein the thermoplastic adhesive is attached to two corner portions of the heat sink that face each other. 2. A bonding method for bonding a heat sink to a printed board on which a semiconductor chip is mounted, wherein a thermosetting adhesive and a thermoplastic adhesive are alternately arranged on the bonding surface of the heat sink and the printed board. In the bonding step, the heat radiating plate and the printed board have a square shape corresponding to each other, and the thermosetting adhesive is attached to each corner of the printed board, A bonding method, wherein the thermoplastic adhesive is attached to a central portion of each side. 3. A bonding method for bonding a heat sink to a printed board on which a semiconductor chip is mounted, wherein a thermosetting adhesive and a thermoplastic adhesive are alternately arranged on the bonding surface of the heat sink and the printed board. In the bonding step, the heat radiating plate and the printed board have a rectangular shape corresponding to each other, and the thermosetting adhesive is attached to a central portion of each side of the printed board, and the heat dissipation is performed. A bonding method, wherein the thermoplastic adhesive is applied to each corner of a plate. 4. The bonding method according to claim 1, wherein the thermosetting adhesive is a silicone-based elastomer liquid adhesive having thermal conductivity. 5. The bonding method according to claim 1, wherein the bonding surface of the printed board is constituted by a surface of a reinforcing member fixed to the printed board. .