JPH08156009A - Resin molding device - Google Patents

Abstract

PURPOSE: To surely prevent a resin from leaking from a cavity by providing an outer wall surface which is almost parallel to the lateral wall of a lead and a projecting part with an inner wall surface which is not parallel to the outer wall surface, on a part adjacent to the lead in a crushable block. CONSTITUTION: A projecting part 21 which holds a region near the base of a tongue piece 7a jutting out of an outermost lead or the intermediate part of the tongue piece 7a, is provided on the inner bottom surface of a protrusion wall so that the tongue piece 7a of a lead frame is stored into a crushable block. The outer wall 21a of the projecting part 21 is parallel to the lateral wall of the lead, and the inner wall 21b is nonparallel to the outer wall 21a. In addition, when a molding operation is performed, the base and the intermediate part of the tongue piece part 7a are held between a top force 15 of a die and the projecting part 21 of the crushable block 19. Further, the pressure-crushed holding part and the non-held part are deformed. As this deformation is such that the inner wall 21b of the projecting part 21 is non- parallel with the lateral wall of the lead, the pressure crush amount is significant at a large width part. Thus the tongue piece 7a is caused to inflate in a width direction to eliminate a clearance between the tongue piece 7a and the inner wall of the crushable wall 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin mold device for a lead frame having a structure in which a tie bar connecting a large number of leads is projected from the outermost lead, and more particularly, a resin mold for preventing resin leakage at both ends of the tie bar. Regarding the device.

[0002]

2. Description of the Related Art An example of a resin mold type electronic component will be described with reference to FIG. In the figure, 1 is a mounting hole 1a at one end
In the illustrated example, the heat radiating plate 2 is a set of three leads, the central lead 2a is connected to the heat radiating plate 1, and the other leads 2b and 2c are arranged with their free ends near the heat radiating plate 1. Has been done. 3 is an electronic component body mounted on the heat sink 1, for example, a semiconductor pellet, 4 is a thin metal wire that electrically connects an electrode (not shown) on the semiconductor pellet 3 and the leads 2b, 2c, and 5 is a semiconductor pellet 3. A main part of the heat sink 1 and the lead 2 including <the resin covering the inner circumference of the mounting hole 1a is shown. This semiconductor device is generally manufactured using the lead frame shown in FIG. In the figure, the same reference numerals as those in FIG. In the figure, reference numeral 6 denotes a lead frame, and leads 2b and 2c are arranged in parallel on both sides of a central lead 2a connected to the heat dissipation plate 1, and a plurality of sets of three leads 2 are arranged in parallel. The intermediate portion of the lead 2 and the end portion on the opposite side to the heat dissipation plate 1 are connected and integrated by first and second connecting members (tie bars) 7 and 8, respectively.

A tongue piece 7a of the first connecting member 7 (hereinafter, simply referred to as a tie bar) in the middle of the inner leads of the connecting member projects outward from the outermost lead. This lead frame 6
Is guided by the guide rails, and the mounting step of mounting the semiconductor pellets 3 on the heat dissipation plate 1 via an adhesive such as molten solder or conductive paste, the electrodes on the semiconductor pellets 3 and the leads 2b, 2c on the thin metal wires 4. A wire bonding step of electrically connecting with each other, a resin molding step of covering a main part including the semiconductor pellet 3 with a resin 5,
Cutting process for cutting and removing unnecessary parts of the lead frame 6 such as the tie bar 7, the tongue piece 7a, and the second connecting member 8 to separate into individual semiconductor devices, a lead forming process, and an electrical inspection for making a pass / fail judgment by electrical measurement. It is manufactured through a process, an appearance inspection process, and the like. Here, in the resin molding process, the lead frame 6 is usually formed by a pair of upper and lower molds having a cavity for accommodating the heat dissipation plate 1 portion of the lead frame 6 formed in the abutting surface.
, The resin tablet is heated and pressurized to be fluidized, and the fluidized resin is injected into the cavity to coat the semiconductor pellet 3 with the resin.

An example of this will be described with reference to FIG. In the figure, reference numeral 9 denotes a lower mold, and a claw portion 10, a runner 11 communicating with the cull portion 10, and a plurality of lower cavities 12a arranged along the runner 11 for accommodating the heat dissipation plate 1 of the lead frame 6 in the figure. , A gate 13 that connects the runner 11 and the cavity 12a is formed. (A-A in the illustrated example
The left side of the plane shows a cross section along the runner 11, and the right side of the A-A plane shows a cross section orthogonal to the runner 11. Further, the tongue is obtained by extending the tie bar 7 of the lead frame 6 placed on the lower mold 9. A crushing block 14 is arranged at the piece 7a portion as shown in FIG. This crushed block 1
As shown in FIG. 8, 4 is the same height as the thickness of the lead frame 6, and the planar shape is formed in a U shape surrounding the tongue piece 7a.
The inner bottom surface 14a is formed as a flat surface projecting from the mounting surface 9a of the lead frame 6.

Reference numeral 15 designates an upper mold, which is penetrated by a pot 16 at a position opposed to the cull portion 10 of the lower mold 9 and which has a lower cavity 12.
An upper cavity 12b is formed at a position facing a. The upper and lower molds 9 and 15 clamp the lead frame 6 and clamp the molds.
b, the peripheral edges of the mold recesses such as the pot 16 abut each other, the lead frame 6 has its lead portion 2 clamped by the upper and lower molds, and the tie bar 7 constitutes a part of the inner wall of the cavities 12a and 12b. A space communicating with the cavity 12 is formed. On the other hand, since there is no tie bar outside the outermost lead, part of the cavity 12 is released and the resin supplied into the cavity 12 leaks, so the tie bar 7 is extended to form the tongue piece 7a. The piece 7a and the crushing block 14 prevent resin leakage. 17 is pot 16
2 shows a plunger that is inserted into the base plate and presses the resin tablet 18. Although not shown, the upper and lower molds 9 and 15 are fixed to a fixed platen and a movable platen, respectively, and are vertically moved to be heated by a heating means.

The resin molding work using this apparatus will be described below. First, the upper and lower molds 9 and 15 are opened, and the heat sink 1
The semiconductor pellet 3 is mounted on the semiconductor chip 3, and the lead frame 6 in which the electrodes on the semiconductor pellet 3 and the leads 2b and 2c are connected by the thin metal wires 4 is attached to the cavity 1 of the lower mold 6.
Place at 2a position. At this time, the extended portion 7a of the tie bar 7
Are placed in the crushing block 14. Next, the upper and lower molds 9,
When the lead frame 6 is clamped by sandwiching the lead frame 6 at each abutting surface with 15 relatively close to each other, the cull portion 10 to the cavity 1
The peripheral edges of the mold recesses such as 2a and 12b and the pot 16 abut against each other, and the lead frame 6 has the lead portion 2 clamped by the upper and lower molds.
A space communicating with is formed.

In the crushing block 14, a part of the tongue piece 7a is crushed and flattened to be expanded and flattened.
Prevents resin leakage by narrowing the space between and. Thereafter, when the resin tablet 18 is put into the pot 16 and the plunger 17 is inserted and the resin tablet 18 is heated and pressurized to be fluidized, the fluidized resin is passed from the runner 11 through the gate 13 to the cavities 12a and 12b. Is injected into and resin molding is performed. When resin molding is completed, molds 9 and 1
5 is opened, the lead frame 6 whose main portion is covered with resin is taken out, and unnecessary resin filled in the cull portion 10, the runner 11, the gate 13 and the like is removed to obtain a resin molded product. If necessary, the lead frame 6 is plated before or after the cutting work so as to improve the solderability by immersing the lead 2 portion in the molten solder.

By the way, when resin leaks from the cavity 12 during resin molding, the leaked resin is used in the molds 9 and 15.
A thin resin film (resin burr) is formed on the surface of the lead frame by advancing along the surface of the lead frame 6 from between. Since the lead frame in the mold is heated and the surface is oxidized, the adhesion of the resin burr is good, and the resin burr is directly cured by the heat from the mold. On the other hand, in the lead frame 6, a plating layer having good solderability is formed on the lead 2 as necessary, but if there is resin burr on the surface of the lead, the plating layer will be in a floating state, and an electrical connection to a circuit board or the like will occur. Since there is a problem that the connection is uncertain, a small protrusion is provided on the tie bar 7 or the clamping surface of the tie bar 7 of the upper and lower molds to crush the tie bar 7 or make part of the mold bite into the tie bar 7 and adhere to each other. Thus, the resin leakage from the tie bar 7 to the lead 2 is prevented. (For example, JP-A-62-2
Also, the outermost lead is crushed by the crushing block 7 with the tongue piece 7a, and the inner wall of the crushing block 14 and the tongue piece 7a are crushed.
The gap between them is narrowed, or the tongue piece 7a is crushed and brought into close contact with the inner wall of the block 14 to prevent the resin leaking from the cavity 12 from flowing out.

[0009]

However, the lead frame 6 has variations in dimensions such as length and thickness,
If the length of the lead frame 6 is shorter than a predetermined length, the length of the tie bar 7 is also shortened, and as a result, the mounting length of the tongue piece 7a on the crushing block 14 is shortened and the amount of crush deformation is reduced, resulting in crushing. It was not possible to prevent the formation of a gap that communicates between the inner wall of the block 14 and the tongue piece 7a, and it was not possible to prevent resin leakage. Similarly, even if the tongue piece 7a is thinner than a predetermined thickness, the amount of crushing becomes insufficient and resin leakage may occur.

On the contrary, when the length of the lead frame 6 is longer than the predetermined length, the crushing amount of the tongue 7a can be made sufficiently large and the resin leakage can be prevented, but the tie bar 7 is clamped by the upper and lower molds 15. There is a possibility that the deformation stress may be applied to the tie bar 7 before, and the tie bar 7 may be pressed from both sides to be curvedly deformed to displace the heat dissipation plate 1 in the cavity 12. In this way, when the resin leaks at the tongue piece 7a, the resin adheres to the lead portion to be soldered at the time of mounting, and the resin adheres to the side wall of the lead. When this is sent to, the part cannot be plated, and there is a risk of defective soldering, and improvement has been desired. Further, if the position of the heat dissipation plate 1 in the cavity 12 shifts due to the curved deformation of the tie bar 7, the resin coating thickness may vary, and the moisture resistance may decrease.

[0011]

SUMMARY OF THE INVENTION The present invention has been proposed for the purpose of solving the above-mentioned problems, and a large number of sets of leads including leads electrically connected to an electronic component body are provided in parallel with each other. A cavity into which a resin is injected, which accommodates a region including an electronic component body and a lead free end portion of a lead frame that is integrated by projecting both ends of a tie bar that connects and arranges the intermediate portions of the leads from the outermost lead, In a resin molding apparatus in which a crushing block having a U-shaped planar shape and an inner bottom surface projecting from a lead supporting surface and accommodating both end portions of a tie bar of a lead frame is formed in a pair of upper and lower mold abutting surfaces, Provided is a resin molding device characterized in that a convex portion having an outer wall surface substantially parallel to the side wall of the lead and an inner wall surface not parallel to this surface is provided in a portion adjacent to the lead. In this case, the outer wall surface and the inner wall surface of the convex portion formed in the crushed block may be non-parallel when viewed from the cross-sectional direction, or the outer wall surface and the inner wall surface of the convex portion formed in the crushed block may not be planar. It can also be parallel.

[0012]

According to the present invention, the crushing deformation amount of the tongue piece in the crushing block can be secured and the deformation direction can be regulated by the above means for solving the problem, so that the resin leakage can be reliably prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG.
In the figure, the same parts as those in FIG. 7 are designated by the same reference numerals, and overlapping description will be omitted. 7 is different from that shown in FIG. 7 only in the crushing block 19, and is shown in FIG. 2 on the inner bottom surface of the projecting wall formed in a U shape in plan view so as to accommodate the section 7a of the lead frame 6. As shown, a convex portion 21 for sandwiching the vicinity of the base portion or the middle portion of the tongue piece 7a protruding from the outermost lead is provided, and the outer wall 21a of the convex portion 21 is made parallel to the side wall of the lead 2 and the outer wall 21a It is characterized in that the inner wall 21b is made non-parallel to. In the illustrated example, the upper end surface 21c of the convex portion 21 is formed as an inclined surface that descends and inwards, but may be a flat surface.

A gap is formed between the intermediate portion or the free end of the tongue piece 7a and the inner bottom surface of the crushing block 19.
In this device, the resin molding work is performed in the same manner as the conventional device, but in the tongue piece 7a portion, the base portion or the middle portion thereof is as shown in FIG.
It is sandwiched by 1 and is further crushed to deform the sandwiched portion of the tongue piece 7a, and the intermediate portion or the free end portion not sandwiched by the die of the tongue piece 7a is also deformed. This deformation is because the inner wall 21b of the convex portion 21 is not parallel to the side wall of the lead 2,
Since the width of the sandwiched portion is different and the crushing amount is large in the wide portion, the tongue piece 7a can be bulged in the width direction (the direction indicated by the arrow in FIG. 1) to eliminate the gap between the crushing block 19 and the inner wall. it can. This deformation is absorbed in the crushing block 19, and the free end portion of the tongue piece 7a extends in the direction opposite to the tie bar 7, so that the deformation stress does not reach the tie bar 7 and the lead frame 6 is deformed by deforming the tongue piece 7a. It does not deform.

By tilting the upper end surface 21c of the convex portion 21 downward inward as in the illustrated example, the influence on the tie bar 7 can be further alleviated and the deformation of the tongue piece 7a in the crushing block 19 can be made remarkable. As a result, the deformation of the tongue piece 7a can be concentrated in the crushing block 19 without escaping to the tie bar 7 side, so that the resin leakage at the end of the lead frame can be reliably prevented and the resin attached to the lead can be removed. It is possible to realize a resin-molded electronic component with good mountability, which does not require any work and can perform good plating work on leads. The present invention is not limited to the above-described embodiment, and for example, as shown in FIG. 3, the inner wall 21b of the convex portion 21 in the crushing block 19 is continuously non-parallel to the width direction of the tongue piece 7a. You can also Further, in the illustrated example, the convex portion 2 formed in the crushed block 19
The outer wall surface 21a and the inner wall surface 21b of FIG. 1 are both non-parallel both in a plan view and in a cross-sectional direction, but they may be non-parallel in any one direction.

[0016]

As described above, according to the present invention, it is possible to surely prevent the resin from leaking from the cavity at the time of resin molding, the work of removing the resin adhering to the side wall of the lead is unnecessary, and the work of plating the lead is also performed. It is possible to realize a resin-molded electronic component that is excellent and has good mountability.

[Brief description of drawings]

FIG. 1 is a plan view of an essential part of a resin molding apparatus showing an embodiment of the present invention.

2 is a sectional view taken along line CC of the apparatus shown in FIG.

FIG. 3 is a plan view of a main part of a resin molding device showing a modified example of the present invention.

FIG. 4 is a partial sectional perspective view showing an example of a resin mold type electronic component.

5 is a partial plan view of a lead frame used for manufacturing the electronic component shown in FIG.

FIG. 6 is a side sectional view of a resin molding device used for manufacturing the electronic component shown in FIG.

7 is a partially enlarged plan view of the resin molding device shown in FIG.

FIG. 8 is a sectional view taken along line BB of FIG.

[Explanation of symbols]

 3 electronic component main body 2 lead 7 tie bar 7a tongue piece 6 lead frame 5 resin 12 cavity 19 crushing block 20 convex wall 21 convex portion 21a outer wall 21b inner wall

Claims (3)

[Claims] 1. A tie bar having a plurality of sets each including a lead electrically connected to an electronic component body, the sets being arranged in parallel with each other and connecting the middle portions of the leads to project from both ends of an outermost lead. A cavity for accommodating the resin including the electronic component body and the lead free end portion of the integrated lead frame and the resin is injected, and the inner bottom surface protruding from the lead supporting surface and the lead frame tie bar. In a resin molding apparatus in which a crushing block containing both ends is formed on a pair of upper and lower mold abutting surfaces, an outer wall surface substantially parallel to a side wall of the lead and this surface are provided on a portion adjacent to the lead in the crushing block. A resin molding device characterized in that a convex portion having an inner wall surface which is non-parallel to the convex portion is provided. 2. The resin molding apparatus according to claim 1, wherein an outer wall surface and an inner wall surface of the convex portion formed in the crushed block are not parallel to each other in plan view. 3. The resin molding apparatus according to claim 1, wherein an outer wall surface and an inner wall surface of the convex portion formed in the crushed block are not parallel to each other when viewed in a sectional direction.