JP2000195876A - Apparatus for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize stable mounting of a semiconductor pellet on a radiation plate with a thickness of 10 μm or less with the use of silver paste, which was difficult in prior arts. SOLUTION: In an apparatus for manufacturing a semiconductor device, wherein a chucking collet 17 with a resilient force applied downward is mounted vertically movably on a guide shaft 15 extended downward from the lower end of a collet holder 14 and a pellet 1 chucked by the collet 17, is mounted on a scheduled mount part 2 via a viscous adhesive material 7 disposed therebetween, the collect 17 is made rockable under the condition that the pellet 1 is pushed against the adhesive material 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for mounting a semiconductor pellet on a mounting portion such as a lead frame via a viscous adhesive.

[0002]

2. Description of the Related Art A method of manufacturing a semiconductor device using a lead frame will be described with reference to FIG. In the figure, reference numeral 1 denotes a semiconductor pellet having electrodes (not shown) on both surfaces, and reference numeral 2 denotes a radiator plate for mounting the semiconductor pellet 1, and has a mounting hole 2a formed therein. Reference numeral 3 denotes a set of three leads. A central lead 3a is connected to one end of the heat sink 2, and other leads 3b and 3c are arranged in parallel on both sides. The lead 3 is connected by a tie bar 4 indicated by a dotted line in the middle and an outer end is connected by a connecting strip 5 to form a lead frame 6 integrated with the heat sink 2. 7 is a semiconductor pellet 1
Is a bonding material for bonding the electrodes on the semiconductor pellet 1 to the leads 3b and 3c, and 9 is an exterior resin covering the semiconductor pellet 1.
This semiconductor device includes a mounting step of supplying a fixed amount of the adhesive 7 onto the heat sink 2 of the moving lead frame 6, a wire bonding step of electrically connecting the electrodes on the semiconductor pellet 1 and the leads 3 b, 3 c with wires 8, A resin molding step of covering and covering the entire surface of the heat sink 2 including the semiconductor pellet 1 with the exterior resin, and cutting and removing unnecessary portions of the lead frame 6 such as the tie bars 4 and the connecting strips 5 shown by dotted lines exposed from the exterior resin 9. The wafers are sequentially manufactured through a cutting process of separating them individually, and then shipped after an electrical characteristic inspection process, a stamping process, a lead molding process, and the like. By the way, in the mounting step, solder or resin-based adhesive is used as an adhesive. However, when a resin-based adhesive is used as a semiconductor pellet having electrodes on both surfaces, a powdery resin is used as a base resin such as an epoxy resin having heat resistance. In general, silver paste in which conductivity and thermal conductivity are improved by kneading silver in the form of filaments or flakes is generally used. This mounting step will be described with reference to FIG. In the figure, reference numeral 10 denotes a guide rail for guiding the lead frame 6 and feeding the same at a constant pitch.
An adhesive supply unit that moves up and down at the upper fixed position and supplies a fixed amount of the viscous adhesive 7 on the heat sink 2, and 12 supplies the semiconductor pellet 1 on the viscous adhesive 7 on the heat sink 2. The collet holder 14 at the tip of the arm 13
Is fixed, a spring 16 is inserted through a guide shaft 15 extending downward from the lower end of the collet holder 14, and a suction collet 17 is attached to the lower end so as to be vertically movable.
Collet holder 14, guide shaft 15, suction collet 17
Although not shown in the drawing, a suction hole is connected and connected to a negative pressure source. The suction collet 17 adsorbs the semiconductor pellet 1 on the lower surface at the side of the guide rail 10, moves up on the guide rail 10, descends and presses the lower surface of the semiconductor pellet 1 against the viscous adhesive 7, When the suction is stopped and the suction collet 17 is raised, the mounting operation is completed. During the above operation, when the semiconductor pellet 1 is pressed against the viscous adhesive material 7 by lowering the arm 13, the elastic force from the spring 16 compressed on the suction collet 17 whose descent has been stopped acts on the suction collet 17. 17 prevents the load on the semiconductor pellet 1 from becoming excessive. The viscous adhesive 7 supplied on the heat sink 2 is not completely flat, but if the heat sink 2 and the semiconductor pellet 1 adsorbed by the adsorption collet 17 are parallel, the viscous adhesive When the semiconductor pellet 1 is pressed with the elastic force applied to the material 7, the viscous adhesive 7 spreads over time, and the semiconductor pellet 1 can be mounted with a uniform thickness.

[0003]

However, there is a problem that it takes time for the viscous adhesive 7 to spread to a uniform thickness, and the production index becomes long. In addition, since the power semiconductor device generates a large amount of heat from the pellet, it is necessary to use solder as an adhesive in order to efficiently transmit the heat generated in the semiconductor pellet 1 to the heat radiating plate 2. Although it is necessary to reduce the resistance as much as possible, the base resin of the viscous adhesive 7 is an insulating material, and the heat conductivity is much lower than that of silver. Therefore, it is necessary to reduce the thickness of the viscous adhesive 7 and directly connect the semiconductor pellet 1 and the heat sink 2 thermally and electrically with silver contained in the viscous adhesive 7. On the other hand, the supply amount of the resin in the adhesive supply unit 11 is determined by the planar dimensions of the semiconductor pellet 1 and the required thickness of the adhesive. Variations are also significant. For this reason, it is difficult to supply a small amount of adhesive in a predetermined thickness, and if the supply position is deviated, there is a portion where the adhesive does not wet between the semiconductor pellets 1 supplied in parallel to the heat sink, When the suction operation of the suction collet 17 is stopped to open the semiconductor pellet 1, the semiconductor pellet 1 may be mounted in an inclined manner. When the viscous adhesive 7 is biased in this way, heat conduction and electric resistance increase, and the performance of the semiconductor device cannot be sufficiently exhibited. If the semiconductor pellet 1 is tilted, the wire bonding operation is hindered. There is a problem, and it has been particularly difficult to eliminate lead-containing solder in power semiconductor devices.

[0004]

SUMMARY OF THE INVENTION The present invention has been proposed for the purpose of solving the above-mentioned problems, and comprises a suction collet which is given a downward elastic force and moves up and down, and a semiconductor pellet adsorbed on the lower surface of the collet. The present invention provides an apparatus for manufacturing a semiconductor device, characterized in that it can swing while being pressed against a conductive adhesive.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a semiconductor device manufacturing apparatus according to the present invention, a suction collet can be swung while a semiconductor pellet is pressed against a viscous adhesive, and the suction collet is connected. The collet holder is inserted through the cylindrical holder guide to guide the collet holder up and down freely, and a gap is formed between the inner circumference of the holder guide and the outer circumference of the collet holder including the guide shaft at a fixed axial position. By swinging the collet holder, the suction collet can be swung. In this case, by applying ultrasonic vibration to the swingable suction collet, the viscous adhesive is liquefied, and the contact between the semiconductor pellet and the viscous adhesive can be made smooth. A silver paste can be used as an adhesive for this device, and good adhesion can be achieved even when the thickness is 15 μm or less.

[0006]

FIG. 1 shows an embodiment of the present invention.
In the drawings, the same components as those in FIGS. 6 and 7 are denoted by the same reference numerals, and overlapping description will be omitted. The only difference between the figures is that a holder guide 18 for inserting the collet holder 14 is provided, and the holder guide 18 is fixed to the arm 13. The opening diameter of the lower end 18a of the holder guide 18 is smaller than that of the collet holder 14 to prevent the collet holder 14 disposed inside from falling, and is engaged internally to make the axes of the collet holder 14 and the holder guide 18 coincide. I am trying to do it. Also, the inner diameter of the holder guide 18 in the axial middle or upper end is formed larger than the collet holder 14,
Furthermore, the upper end 18b is closed to stop the collet holder 14 from rising. The concavity and convexity portion 14 that contacts with a very small area is formed on the opposing surface of the upper end closing portion 18b and the upper end of the collet holder 14.
a, 18c are formed, and the collet holder 14 can swing around the axis of the holder guide 18. The arm 13 is movable within a small radius around the lowering position on the heat sink 2, and although not shown, when the collet holder 14 is at the lowering position, the collet holder 14 and the holder guide 18 are coaxially arranged. At the same time, a guide mechanism such as a guide pin and a guide groove is formed so as to face each other at the same position. 19 is connected to a negative pressure source and the holder guide 1
8 shows a pipe which is connected to the collet holder 14 through a hole 18d penetrating the upper end 18b of the 8 and communicates with the lower end of the suction collet 17 via the guide shaft 15. The operation of this device will be described below. First, the arm 13 is raised, and the suction collet 17 is moved to a semiconductor pellet supply position (not shown) outside the guide rail 10. In this state, the collet holder 17 is lowered by its own weight inside the holder guide 18, and the suction collet 17 is at the lowermost position by the spring 16. When the semiconductor pellet 1 is adsorbed to the lower end of the suction collet 17, the arm 13 is raised and moved horizontally so that the viscous adhesive 7 on the guide rail 10 is supplied onto the heat sink 2 as shown in FIG. Moving. Subsequently, the arm 13 is lowered to stop at a height position where the lower surface of the semiconductor pellet 1 and the upper surface of the heat sink 2 are at a predetermined interval as shown in FIG. When the thickness of the adhesive 7 after mounting the pellet 1 is 10 μm, the height position is set to 12 μm to 15 μm without the adhesive 7.
When the semiconductor pellet 1 is pressed onto the adhesive 7 with the height position of the suction collet 17 set in this way, the collet holder 14 rises in the holder guide 18 and the concave and convex portions 14a and 18c engage, The spring 16 is compressed to apply a downward elastic force to the suction collet 17. At this time, if the adhesive 7 supplied on the heat sink 2 is biased as shown by the dotted line in FIG. 3, the adhesive 7 pressed by the semiconductor pellet 1 is moved between the pellet 1 and the suction collet 17 in the direction indicated by the arrow. At the position indicated by the dotted line. However, in such a state, the adhesive 7 cannot be spread over the entire lower surface of the semiconductor pellet 1. In the apparatus of the present invention, the arm 13 is driven so that the center of the axis of the suction collet 17 moves as indicated by an arrow in FIG. As a result, the outer periphery of the semiconductor pellet 1 moves within a region 1 'indicated by the dotted line in the figure, but the collet holder 14 swings around the contact portion between the concave and convex portions 14a and 18c. Since the gap is inclined, the gap is wide at the front in the traveling direction of the pellet 1 and narrow at the rear, the adhesive 7 is thinly stretched on the heat sink 2. When the stretching operation of the adhesive 7 is completed in this way, the suction collet 17 is returned to the original position, the semiconductor pellet 1 is placed at the regular mounting position, and the arm 13 is slightly raised, so that the collet holder 1 is lifted.
4 falls in the guide holder 18, and the semiconductor pellet 1 and the heat sink 2 become parallel. After that, the arm 13 is lowered and the distance between the semiconductor pellet 1 and the heat sink 2 is set to 10 μm.
When the suction collet 17 is lowered so as to satisfy the following condition, both can be mounted with the adhesive 7 having a thickness of 10 μm.
Thus, the thickness of the device of the present invention is reduced to 15 μm or less,
In particular, since the thickness of the adhesive 7 is extremely small, the thickness of the adhesive 7 can be reduced even when the supply position of the adhesive 7 is small due to a small amount of the adhesive 7 to be supplied. Can be mounted. An ultrasonic oscillator is fixed to the upper end of the collet holder 14 of the apparatus shown in FIG. 1, and when the semiconductor pellet 1 adsorbed by the adsorption collet 17 is moved on the adhesive 7, ultrasonic vibration is generated. By simultaneously moving the pellet 1 horizontally and microvibrating the contact surface with the adhesive 7, the adhesive 7 is liquefied, the fluidity is improved, and the spread of the adhesive 7 can be improved. In the device of the present invention, a common molten solder can be used as the viscous adhesive, but when a metal having good conductivity and heat conductivity is used as the base resin, for example, when a silver paste in which silver is dispersed is used, silver is used. Even when the amount of the paste is small and it is not possible to supply the heat spread over the heat radiating plate 2 beforehand, the thickness can be set to 15 μm or less, and the heat generated inside the semiconductor pellet 1 can be efficiently transmitted to the heat radiating plate 2. And electrical resistance can be reduced,
Solder conventionally used as an adhesive can be replaced with silver paste, and a power semiconductor device containing no lead can be realized.

[0007]

As described above, according to the present invention, even when the amount of the viscous adhesive is small, the supply position is varied, and the supply amount is easily varied, the adhesive layer having a constant thickness is formed on the entire lower surface of the semiconductor pellet. Can be formed. In particular, by using a silver paste as the viscous adhesive, a power semiconductor device containing no lead can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional side view of a main part showing an embodiment of the present invention.

FIG. 2 is a side view of an essential part for explaining the operation of the apparatus in FIG. 1;

FIG. 3 is a side view showing a main part of the semiconductor pellet mounted by the apparatus shown in FIG. 1;

FIG. 4 is a top view of FIG. 3;

FIG. 5 is a side view of a main part showing a state in which an adhesive of the apparatus in FIG. 1 is spread;

FIG. 6 is a partial cross-sectional plan view illustrating an example of a semiconductor device.

7 is a front view of a mounter for manufacturing the semiconductor device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor pellet 2 Heat sink (planned mounting part) 7 Viscous adhesive material 14 Collet holder 15 Guide shaft 16 Spring 17 Suction collet

Claims (5)

[Claims] An attraction collet provided with a downward elastic force is mounted on a guide shaft extending downward from a lower end of a collet holder so as to be vertically movable, and a semiconductor pellet adsorbed by the attraction collet is mounted on a mounting portion. An apparatus for manufacturing a semiconductor device mounted on a viscous adhesive via a viscous adhesive, wherein the adsorbing collet is allowed to swing while the semiconductor pellet is pressed against the viscous adhesive. Manufacturing equipment. 2. A collet holder is inserted through a cylindrical holder guide to guide the collet holder so as to be movable up and down, and a gap is formed between the inner periphery of the holder guide and the outer periphery of the collet holder including the guide shaft at a fixed axial position. 2. The apparatus according to claim 1, wherein the suction collet is swingable. 3. The apparatus for manufacturing a semiconductor device according to claim 1, wherein ultrasonic vibration is applied to the swingable suction collet. 4. An apparatus according to claim 1, wherein the viscous adhesive is a silver paste. 5. The apparatus according to claim 4, wherein the thickness of the silver paste is 15 μm or less.