JP2569813B2 - Cooling structure for surface mount semiconductor components - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cooling structure for a surface mount semiconductor component.

[Prior Art] Conventionally, in a surface-mounted semiconductor device such as an LSI to which a heat sink for heat dissipation is attached, an attachment structure of a heat sink as shown in FIGS. 3 and 4A and 4B is adopted. Was.

FIG. 3 is a cross-sectional view showing a conventional LSI in which a heat sink is bonded to an LSI case with an adhesive, and FIG. 4 (a) is a conventional LSI in which a heat sink is detachably attached to a stud.
FIG. 4B is a cross-sectional view showing the LSI, and FIG. 4B is a plan view of the heat sink. The mounting structure of the heat sink shown in FIG.
No. 58-25249. In these figures, reference numeral 1 denotes an LSI case. The LSI case 1 incorporates a semiconductor element 2 and is surface-mounted on the printed board 4 by soldering a lead 3 to a wiring pattern (not shown) of the printed board 4. Have been. Also, as shown in FIG.
A heat transfer plate 5 to which the semiconductor element 2 is bonded is fixed to the LSI case 1. Reference numeral 6 denotes a heat sink for dissipating heat generated from the semiconductor element 2. In the heat sink mounting structure shown in FIG. 3, the heat sink 6 is adhered to the LSI case 1 via an adhesive 7. Note that the adhesive 7 mixed with a filler having high thermal conductivity such as silver particles is used. In the heat sink mounting structure shown in FIG. 4 (a), a heat sink 6 having a mounting hole 6a as shown in FIG. 4 (b) is used. A stud 9 integrally projecting from the hot plate 5 is fitted to the mounting hole 6a. In an LSI to which a heat sink is attached using the stud 9, there is a structure in which a screw hole is provided in the stud 9 and the heat sink 6 is screwed.

In the LSI shown in FIG. 3, heat generated by the semiconductor element 2 is conducted from the LSI case 1 to the heat sink 6 via the adhesive 7 and is radiated from the heat sink 6 into the air. In the LSI shown in FIG. 4 (a), heat generated from the semiconductor element 2 is conducted from the heat transfer plate 5 to the heat sink 6 via the stud 9, and is radiated from the heat sink 6 into the air. Become.

[Problems to be solved by the invention]

However, if a structure in which the heat sink 6 is bonded to the LSI case 1 via the adhesive 7 as shown in FIG.
Once attached, the heat sink 6 cannot be removed. For this reason, when surface mounting components such as flat packs are mounted on the front and back surfaces of the printed board 4, if the LSI having the heat sink 6 is mounted on one side of the printed board 4, the heat sink 6 causes unevenness, and the printed board 4 is held. This not only makes it difficult, but also hinders the mounting and soldering of other surface mount components. In addition, the heat sink 6 has been increased in size due to an increase in the amount of heat generated due to the recent high integration of the semiconductor element 2, and the heat capacity thereof has been increased. And soldering defects are likely to occur. Furthermore, if the heat sink 6 is adhered, the work becomes difficult to be performed by the heat sink 6 even when the wiring pattern of the printed board 4 is modified after the mounting, and there is also a problem that it is difficult to perform the pattern cutting and wiring addition work. there were.

Also, as shown in FIG. 4 (a), even when a stud 9 and a heat sink mounting screw (not shown) are provided on the LSI case 1 to fix the heat sink 6, irregularities due to the stud 9 and the screw are printed. It becomes an obstacle when both sides are mounted on the board 4. Also, since the lead pitch of a surface mount component such as a flat pack is very small, mounting on the printed board 4 is being performed by an automatic device, and the LSI case 1 is transferred to the printed board 4 and positioned. Regardless of whether it is a suction type or a clamp type, a holding tool to be used must have a special structure because projections such as studs and screws become obstacles. Furthermore, if the stud 9 and the screw are of a structure attached to the LSI, this part is likely to break or bend unless care is taken.

[Means for solving the problem]

A cooling structure for a surface-mounted semiconductor component according to the present invention includes a wiring substrate, a semiconductor component having a flat upper surface mounted on the wiring substrate, and a flat upper surface bonded to the upper surface of the semiconductor component. A mounting plate having a female screw threaded inward from the upper surface, a male screw screwed into the female screw of the mounting plate, and a heat sink attached to the upper surface of the mounting plate by the male screw.

(Operation)

The heat sink can be freely removed from the case of the surface mount semiconductor device by loosening the screws.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIG. 1 and FIG.

FIG. 1 is a plan view showing an LSI adopting a mounting structure for a heat sink for a surface-mount type semiconductor device according to the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG. In these figures, the same reference numerals are given to the same or equivalent members as those described in FIGS. 3 and 4 (a) and (b), and the detailed description is omitted here. 1 and 2, reference numeral 11 denotes a heat transfer plate which constitutes a part of the LSI case 1. The heat transfer plate 11 is formed of metal, and has an upper surface protruding upward from the LSI case 1. LSI case 1
Buried in The semiconductor element 2 is directly bonded to the heat transfer plate 11 so that heat generated in the semiconductor element 2 is directly conducted to the heat transfer plate 11. Further, the upper surface of the heat transfer plate 11 protruding above the LSI case 1 has a flat heat radiation surface 11a.
Are formed. Reference numeral 12 denotes a mounting plate serving as a heat sink support plate for fixing a heat sink to be described later to the LSI case 1. 12a is provided, and is bonded to the heat dissipation surface 11a of the heat transfer plate 11 via an adhesive 13 having high thermal conductivity. 14 is a heat sink, and the heat sink 14 is a screw hole of the mounting plate 12.
A mounting screw insertion through-hole 14a is formed at a position corresponding to 12a, and its lower mounting surface is formed flat.
Reference numeral 15 denotes a heat radiating sheet for electrically insulating the mounting plate 12 and the heat sink 14 and making sure that the mounting plate 12 and the heat sink 14 are in close contact with each other. . 16 is a mounting screw for fixing the heat sink 14 to the mounting plate 12, and 17 is a bushing for electrically insulating the head of the mounting screw 16 from the heat sink 14.

To assemble the LSI configured as described above, first, the heat transfer plate 11, the semiconductor element 2, the lead 3 and the like are attached.
The mounting plate 12 is bonded to the SI case 1. Then, the heat sink 14 is placed on the mounting plate 12 via the heat radiating sheet 15, the mounting screw 16 is inserted from above through the through hole 14 a of the heat sink 14, and the tip end is screwed into the screw hole 12 a of the mounting plate 12. To wear. When the mounting screw 16 is inserted into the through hole 14a of the heat sink 14, the bushing 17 is attached to the heat sink 14 in advance. By tightening the mounting screws 16, the mounting plate 12, heat dissipation sheet 15, and heat dissipation sheet 1
The heat sink 14 and the heat sink 14 are in close contact with each other.
Is fixed to the mounting plate 12 in a state where is interposed. That is, when the heat sink 14 is fixed, the mounting plate 12 and the heat sink 14 are insulated by the heat radiating sheet 15, and the heat sink 14 and the mounting screw 16 are insulated by the bushing 17. The element 2 and the heat sink 14 are insulated.
In the LSI thus assembled, the heat generated from the semiconductor element 2 is transferred from the heat transfer plate 11 to the adhesive 13,
Heat sink 14 via mounting plate 12 and heat dissipation sheet 15
To be dissipated into the air from the heat sink 14.

Therefore, according to the mounting structure of the heat sink for a surface-mount type semiconductor device according to the present invention, the heat sink 14 can be freely removed from the LSI case 1 by loosening the mounting screw 16.

Further, when the heat sink mounting structure according to the present invention is employed, a heat sink having a different heat radiation amount can be selectively used according to the heat generation amount of the semiconductor element 2.

In this embodiment, the example in which the bushing 17 is used to insulate the mounting screw 16 from the heat sink 14 has been described.However, the use of a highly insulating plastic mounting screw eliminates the need for the bushing 17. Can be. Also,
If there is no need to insulate the LSI case 1 from the heat sink 14, the bushing 17 and the heat radiating sheet 15
Can also be omitted.

〔The invention's effect〕

As described above, the mounting structure of the heat sink for a surface-mount type semiconductor device according to the present invention is configured such that a semiconductor element in a case of a surface-mount type semiconductor device is joined to a heat sink support plate having a flat surface for heat transfer formed on an upper surface. Since a heat sink having a flat surface formed on the support plate side is fixed on the support plate via screws screwed to the support plate, the heat sink must be loosened. Thereby, it can be freely removed from the case of the surface mount type semiconductor device. Therefore, it is possible to prevent the heat sink from hindering the work at the time of soldering to the printed board, at the time of inspection, at the time of modifying the pattern of the printed board, and the like. Further, since soldering can be performed on the printed board with the heat sink removed, poor soldering due to uneven temperature is unlikely to occur, and when the heat sink is removed, the flat upper surface of the support plate is exposed. Therefore, it is possible to perform positioning on a printed board or the like using an automatic component mounting machine having a suction mechanism. In addition, since the heat sink support plate is bonded to the metal heat transfer portion to which the semiconductor element is bonded, the heat of the semiconductor element is conducted to the heat sink support plate so that the heat resistance may be small, and high heat radiation performance may be obtained. .

[Brief description of the drawings]

FIG. 1 is a plan view showing an LSI adopting a mounting structure of a heat sink for a surface mount semiconductor device according to the present invention.
The figure is a sectional view taken along the line II-II in FIG. FIG. 3 shows a conventional LSI in which a heat sink is bonded to an LSI case with an adhesive.
FIG. 4A is a sectional view showing a conventional LSI in which a heat sink is detachably attached to a stud, and FIG.
FIG. 2B is a plan view of the heat sink. 1 LSI case, 12 Mounting plate, 12a Screw hole, 13
... adhesive, 14 ... heat sink, 16 ... mounting screws.

Claims (1)

(57) [Claims] A wiring board, a semiconductor component having a flat upper surface mounted on the wiring board, and a flat upper surface bonded to the upper surface of the semiconductor component, and having a flat upper surface, and A surface mounting comprising: a mounting plate on which a female screw is threaded toward the outside; a male screw screwed into the female screw of the mounting plate; and a heat sink mounted on an upper surface of the mounting plate by the male screw. Cooling structure for mold semiconductor parts.