JPH0744193B2 - Method for manufacturing resin-sealed electronic component - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a resin-sealed electronic component having resin layers on both main surfaces of a support plate.

[Problems to be Solved by Prior Art and Invention]

A resin-sealed semiconductor device in which a part of the resin sealing body is formed on the main surface side opposite to the main surface to which the semiconductor chip of the support plate is fixed is an insulator plate with respect to an external heat radiator. It has the advantage that it can be mounted directly without being mounted and the mounting work can be simplified. However, in terms of heat dissipation, it is more disadvantageous than a semiconductor device of the type in which the lower surface of the support plate is exposed.
Therefore, it is necessary to improve the heat dissipation by forming the resin sealing body on the lower surface side of the support plate as thin as possible. The resin sealing body is often formed by a well-known transfer molding method. In this case, in order to form a thin resin layer on the lower surface side of the support plate as described above, the support plate is arranged at a small distance from the bottom surface of the molding cavity, and the sealing resin is injected into this narrow space. Must. For this reason, the sealing resin could not be injected well, resulting in defective molding.

In order to solve this kind of problem, it is possible to provide a convex portion on the upper surface of the molding cavity and suppress the flow of the sealing resin to the upper surface side of the support plate by the convex portion. It is disclosed in Japanese Patent No. 257529. According to the manufacturing method disclosed herein, the resin flow to the lower surface side of the support plate can be relatively strengthened, so that the resin layer on the lower surface side of the support plate can be formed relatively well. But it's not enough. Further, the manufacturing conditions may change in the manufacture of these resin-encapsulated semiconductor devices. For example, a lead frame with a groove on the lower surface of the support plate is used to increase the adhesion to the resin encapsulant, or a sealing resin with less additives is used to improve heat dissipation. To do In such a case, according to the above-mentioned manufacturing method, the speed and balance of the sealing resin flowing above and below the support plate are slightly changed, and it is difficult to perform good resin molding using the same mold. Furthermore, in the resin sealing body obtained by the above manufacturing method, a thin portion is partially formed at a portion corresponding to the convex portion of the mold.
This may cause a decrease in strength of the resin encapsulant.

Also, when performing resin sealing in a state where the support plate is cantilevered by the external leads, it is difficult to hold the support plate at a predetermined height position in the molding cavity, and the upper surface side of the support plate It was difficult to uniformly form a resin layer having a desired thickness on the lower surface side.

Therefore, it is an object of the present invention to provide a method for producing a resin-sealed electronic component, which can form a resin layer with a desired thickness on one and the other main surface sides of a support plate in a favorable manner.

[Means for Solving the Problems] In order to achieve the above object, the present invention has an electronic element and / or a circuit board fixed to one main surface of a supporting plate of a lead frame, and one of the supporting plates is provided. A step of preparing a lead frame assembly in which external leads are arranged on the end side, and a molding space for resin-sealing both one main surface side and the other main surface side of the support plate are provided. First and second main body molds formed so as to be obtained, and relative to the first main body mold and abutting on one main surface of the support plate, one main surface side of the support plate A first slide die formed so as to limit the inflow of sealing resin into the second slide die and a second slide die that moves relative to the second main body die and abuts on the other main surface of the support plate to the other slide die. The position of the main surface of the support plate is limited, but the sealing resin is allowed to flow into the other main surface side of the support plate. A molding die having a second slide die formed thereon, the outer lead being sandwiched between the first and second main body dies, and the other end side of the support plate being the first and second dies. The distance between the other main surface of the support plate and the wall surface of the molding cavity facing the other main surface sandwiched by the second slide die is one main surface of the support plate and the molding cavity facing the one main surface. Arranging the lead frame assembly in the molding die so as to be smaller than the space between the wall surface and the wall, and from the resin injection port leading to the molding cavity by the first slide die to one of the main parts of the support plate. The sealing resin injected into the surface side is restricted, and the flow of the sealing resin to the other main surface side of the support plate is made smaller than the flow of the sealing resin to one main surface side of the support plate. The step of injecting the sealing resin into the molding space while relatively strengthening
And the second slide mold are moved by a predetermined amount in a direction in which they are separated from the one and the other main surfaces of the support plate, and the first and second slide molds are moved.
And a step of injecting a sealing resin into a void formed after the movement of the slide mold, the manufacturing method of the resin-sealed electronic component.

The correspondence between the above invention and the embodiments described later will be described. The first and second main body molds of the present invention are the upper molds 14 of the embodiment.
And the lower die 15, the first slide die of the present invention corresponds to either or both of the first and second slide dies 16 and 17 of the embodiment, and the second slide die of the present invention is It corresponds to the third slide mold 18 of the embodiment.

[Operation] The first slide mold of the present invention limits the sealing resin flowing to the one main surface side of the support plate. Thereby, the flow of the sealing resin flowing to the other main surface side of the support plate can be relatively increased. Therefore, the balance of the sealing resin flowing to the one main surface side and the other main surface side of the support plate is improved,
Good resin molding can be performed. Further, since one end side of the support plate is supported by the external lead and the other end side is sandwiched by the first and second slide molds, the support plate is stably held in the molding cavity, A resin layer having a desired thickness can be formed on one and the other main surface sides of the support plate. Further, since the first and second slide molds can be moved back and forth in the molding space, even under various manufacturing conditions, the moving timing and the moving speed of the first and second slide molds can be arbitrarily set. Good resin molding can be performed. Furthermore, since the sealing resin is injected into the space created after the first and second slide molds are moved, the insulation of the support plate is completely achieved.

〔Example〕

Hereinafter, a method of manufacturing a resin-sealed semiconductor device according to an embodiment of the present invention will be described with reference to FIGS.

First, the lead frame 1 shown in FIG. 9 is prepared. The lead frame 1 is connected to a support plate 2, external leads 3 arranged at one end of the support plate 2, a tieper 4 and a connecting strip 5 for connecting the external leads 3 in parallel, and the other end of the support plate 2. The supporting lead 6 and the connecting body 7 connecting the supporting lead 6 in parallel. Reference numeral 8 is a hole for inserting a screw used for attachment to the external heat radiator. A semiconductor chip 9 is fixed to the lead frame 1 via solder (not shown) by a well-known die bonding method. Further, the fine lead wire 10 is electrically connected to the semiconductor chip 9 and the external lead 3 by a well-known wire bonding method. An assembly composed of the lead frame 1 and the semiconductor chip 9 shown in FIG. 9 will be referred to as a lead frame assembly 11.
Since the support plate 2 of the lead frame assembly 11 is supported on both sides by the outer lead 3 and the support lead 6, the support plate 2 does not largely tilt during the die bonding process or the wire bonding process. The lead frame assembly 11 has a resin encapsulant 12 formed at the portion shown by the dotted line in FIG.

Next, in this embodiment, the supporting lead 6 and the connecting body 7 of the lead frame 1 shown in FIG. 9 are cut and removed to form a lead frame assembly 11 in which the supporting plate 2 is cantilevered.

Next, in order to form the resin sealing body 12 by the transfer molding method, the lead frame assembly 11 is placed in the mold (molding mold) 13 as shown in FIG. Mold 13 is upper mold
14 and lower mold 15 as well as first, second and third slide molds 16, 1
It has 7 and 18. First and second slide molds 16, 17
Can move up and down relatively to the upper mold 14. The third slide die 18 is vertically movable relative to the lower die 15. The upper mold 14 is formed with a concave portion 19 and a cylindrical convex portion 20, and the convex portion 20 is inserted into the hole 8 of the support plate 2. However, since the convex portion 20 is separated from the inner peripheral surface of the hole 8, a part of the resin sealing body 12 is formed on the inner peripheral surface of the hole 8. The lower mold 15 has a recess 21, a groove 22 for inserting the external lead 3,
A runner (resin injection path) 23 and a gate (resin injection port) 24 are provided. By closing the upper mold 14 and the lower mold 15,
Molding space corresponding to the resin sealing body 12 in the mold 13 from 19 and 21
25 are formed.

When arranging the lead frame assembly 11, the outer leads 3 are grooved.
It is fitted to 22 and held between the upper mold 14 and the lower mold 15. Therefore, the lower surface of the support plate 2 is positioned so as to float from the bottom surface of the molding space 25 at a narrow interval L ₁ of about 0.5 mm. Next, the first and second slide molds 16 and 17 are lowered to bring their lower surfaces into contact with the upper surface on the other end side (gate 24 side) of the support plate 2.
Further, the third slide die 18 is raised so that its upper surface is brought into contact with the lower surface on the other end side of the support plate 2. The first and second
The slide dies 16 and 17 are arranged so that their lower surfaces are spaced apart from the bottom surface of the molding cavity 25 by the distance L ₁ and the thickness of the thick portion of the support plate 2. Therefore, the support plate 2 is arranged such that the lower surface thereof extends over the entire surface and is spaced apart from the bottom surface of the molding cavity 25 by the above-mentioned distance L ₁ .

Next, as shown in FIG. 1, a sealing resin 26 made of a thermosetting resin is charged into a pot (resin charging port) 27. Incidentally, the sealing resin 26 is usually put into the pot 27 after being softened by ultrasonic heating or the like. Pot 27 and mold 13 at 160 ° C
By preheating to a certain degree, the sealing resin 26 put in the pot 27 is melted and fluidized.

Next, the sealing resin 26 is pressed by the plunger (sink type) 28 that is movably arranged in the pot 27, the sealing resin 26 is sent to the runner 23, and the gate 24 inside the molding space 25. Inject. In this embodiment, the pot 27 is connected to two molding cavities 25 (one of which is not shown) symmetrically arranged about the pot 27, so that the encapsulating resin 26 also includes two resin-encapsulated semiconductor devices. The size is such that the resin sealing body 12 can be obtained.

When the sealing resin 26 is injected, the first, second and third slide molds 16, 17, 18 are arranged as shown in FIG. The first slide mold 16 is plate-shaped as shown in FIGS. 1 and 2, and one main surface thereof is substantially in contact with the wall surface of the molding cavity 25 provided with the gate 24. Both side surfaces of the first slide die 16 are substantially in contact with the wall surfaces of the molding cavities 25 which face each other. As shown in FIG. 3, the second slide die 17 has a notch portion 17a and a pair of legs 17b and 17c, and like the first slide die 16, on the wall surface of the molding cavity 25 whose both side surfaces face each other. Abutting. In the cutout portion 17a of the second slide die 17, the first
As is apparent from the figure, the protrusion 14a provided on the upper mold 14 is inserted. The lower surface of the protruding portion 14a has a space corresponding to the thickness of the resin sealing body 12 on the upper surface side of the support plate with respect to the upper surface of the support plate 2. Accordingly, the protruding portion 14a has the second slide mold 17
Only part of the notch 17a is filled. Third slide type 18
Is a cutout 18a and a pair of legs 1 as in the second slide die 17.
8b and 18c, one main surface of which is arranged in contact with the wall surface of the molding cavity 25 on which the gate 24 is provided. As is apparent from FIG. 2, the protruding portion 15a provided on the lower die 15 is inserted into the notch portion 18a of the third slide die 18. The upper surface of the protruding portion 15a faces the extension line of the lower surface of the thick portion of the support plate 2 at the narrow interval L ₁ described above. Therefore, the protruding portion 15a fills only a part of the cutout portion 18a of the third slide die 18.

In this embodiment, the gate 24 is arranged below the upper surface of the support plate 2. In addition, the third slide mold 18 also has a leg 18
b and 18c are arranged on both sides of the gate 24. Therefore, in the state of FIG. 1 in which the lower surfaces of the first and second slide molds 16 and 17 are in contact with the support plate 2, the gate 24 directly communicates with the lower side of the support plate 26, It does not directly communicate. In the state shown in Fig. 1, the plunger 28 is lowered and the sealing resin is used.
When 26 is injected into the molding space 25, the flow of the sealing resin 26 that tends to flow to the upper surface side of the support plate 2 is restricted by the first slide mold 16 and the lower surface of the support plate 2. Therefore,
The sealing resin 26 is mainly injected into the lower surface side of the support plate 2. A part of the sealing resin 26 is also injected into the upper surface side of the support plate 2 through the space between the side surface of the support plate 2 and the wall surface of the molding cavity 25. Although not shown in FIG. 1, the same shape as the runner 23, the gate 24, and the molding cavity 25 on the right side of the pot 27 is also provided on the left side of the pot 27. Two
Since the lengths (capacities) of the runners 23 reaching the one molding space 25 are substantially the same, the sealing resin 26 is injected into the two molding spaces 25 at substantially the same ratio.

When it is found from the height position of the plunger 28 that about 60% of the lower side of the support plate 2 is filled with the sealing resin 26, the first slide mold 16 is set to the positions shown in FIGS. 4 and 5. Move upward as shown in. Since the second slide die 17 and the third slide die 18 are not moved, the support plate 2 is prevented from moving up and down. The sealing resin 26 injected from the gate 24 is injected to the upper side of the support plate 2 through the cutout portion 17a of the second slide die 17. In addition, part of the sealing resin 26 is pushed by pushing the sealing resin 26 already injected under the support plate 2 into the support plate 2.
It is also injected on the underside.

When 80% or more of the upper surface of the support plate 2 is filled with the sealing resin 26, the second slide mold 17 and the third slide mold 18 are attached to the support plate 2 as shown in FIGS. 6 and 7. Move away from. As a result, the portions of the second slide die 17 and the third slide die 18 where the legs 17b, 17c, 18b, 18c are located become vacant, and the sealing resin 26 is also injected therein. When the second slide mold 17 and the third slide mold 18 are separated from the support plate 2, the other end of the support plate 2 is not fixed, but most of the lower surface of the support plate 2 is filled with the sealing resin 26. Further, 80% or more of the upper surface of the support plate 2 is filled with the sealing resin 26. Therefore, the vertical movement of the support plate 2 hardly occurs.

After the injected sealing resin 26 is solidified, the lead frame assembly 11 is taken out from the mold 13, and the tie bar 4 and the connecting strip 5 are removed. As a result, as shown in FIG. 8, a resin-sealed type semiconductor device is obtained in which all but the external leads 3 are covered with the resin-sealed body 12. Incidentally, 12a is a hole for inserting a mounting screw.

This embodiment has the following effects.

(1) Since the first slide die 16 restricts the flow of the sealing resin 26 to the upper side of the support plate 2, the sealing resin 26 is supported in the initial period when the sealing resin 26 is injected. The injection can be focused on the lower side of the plate 2. Therefore, the resin layer on the lower surface side of the support plate 2 is not filled.

(2) Even after the first slide die 16 is moved, the support plate 2
The support plate 2 is sandwiched and fixed by the second slide mold 17 and the third slide mold 18 until it is fixed by the sealing resin 26 into which is injected. Therefore, the inclination of the support plate 2 can be reliably prevented, and a thin resin layer having a substantially uniform thickness can be formed on the lower side of the support plate 2.

(3) By changing the type of the sealing resin 26 or processing the surface of the support plate 2, the injection speed of the sealing resin 26 and the vertical balance of the support plate 2 were changed. Even in this case, in the present embodiment, this can be easily dealt with by changing the moving time and moving speed of the first slide die 16.

(4) The slide molds 16, 17, and 18 are movable, and the space after the movement can be filled with the sealing resin 26. Therefore, since the thin portion is not partially formed on the resin sealing body 12, the resin sealing body 12 having high strength can be formed.

(5) After moving the first slide die 16, the second slide die 17 limits the injection of the sealing resin 26 to the upper side of the support plate 2. Therefore, the inflow balance of the sealing resin 26 to the upper and lower sides of the support plate 2 is good, and good resin molding can be performed.

(6) The slide molds 16, 17, 18 are arranged on the other end side (gate side) of the support plate 2, and the lateral widths of the slide molds 16, 17, 18 are formed to be larger than the lateral width of the gate 24.
Since a part of 16 is located on the extension line of the gate 24, the restriction of the resin flow can be achieved well.

[Modification]

The present invention is not limited to the above-mentioned embodiments, and the following modifications are possible, for example.

(1) It is also effective when a thermoplastic resin such as polybutylene terephthalate is used.

(2) In the embodiment, the first slide die 16 having no notch portion is used as the slide die that mainly acts to limit the flow of the sealing resin 26 to the upper side of the support plate.
The slide die 17 may be arranged on the gate 24 side, and the second slide die 17 may be the main limiting slide die. In this case, if you do not use a slide type that does not have a notch,
Even if the second slide die 17 is not separated from the support plate 2, the sealing resin 12 is injected into the upper side of the support plate 2 through the cutout portion 17a.

(3) The entire area of the lower surface side of the support plate 2 is a sealing resin
The resin for sealing is provided on the upper side of the support plate 2 after being filled with 26.
The first slide mold 16 may be separated from the support plate 2 so that 26 may be injected.

(4) The slide molds 16, 17 and 18 are the gate 24 of the molding cavity 25.
You may arrange | position in the position which left | separated only the fixed distance from the wall surface in which it was provided. However, since the flow control effect of the sealing resin is sufficiently obtained and the sealing resin 26 can be satisfactorily injected into the empty space after the slide molds 16, 17, 18 are moved, the supporting plate 2 as in the embodiment is used. On the other end side, preferably, it is arranged to be substantially in contact with the wall surface of the molding space 25.

(5) The slide mold (first slide mold 16) which mainly restricts the injection of the sealing resin 26 onto the upper surface of the support plate 2 has a lateral width W such that the side surface of the slide mold abuts the wall surface of the molding cavity 25 which faces the slide mold. It doesn't have to be long. At this time, the convex portion 2a is provided on the support plate 2 as shown in FIG.
If the slide mold 16 is arranged, the flow of the sealing resin 26 can be suppressed by the first slide mold 16 and the convex portion 2a. However,
The lateral width of the slide type, which mainly limits the injection, is equal to or larger than the lateral width of the gate 24, and it is desirable that a part of the slide type is on the extension of the gate 24.

(6) Part of the gate 24 is provided with legs 18 of the third slide die 18.
It may be closed by b and 18c. In this case, the third slide type
Since the void formed after the movement of 18 directly leads to the gate 24, it is possible to delay the sliding type movement time. Of course, a part of the gate 24 may be closed by the first or second slide molds 16 and 17.

(7) In the embodiment, the slide molds 16, 17, 18 were moved after closing the upper mold 14 and the lower mold 15, but it is possible to project the slide molds 16, 17, 18 into the molding space 25 in advance. Good.

(8) A convex portion may be provided on the upper mold. However, it is necessary to determine the protruding length of the convex portion to such an extent that a thin portion that interferes with the resin sealing body is not formed.

〔The invention's effect〕

As described above, according to the present invention, it is possible to easily obtain the resin-sealed electronic component in which the resin layers are favorably formed on both main surface sides of the support plate.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a mold and a lead frame assembly for manufacturing a resin-sealed semiconductor device according to an embodiment of the present invention in a state before resin injection, and FIG. II-II sectional view, FIG. 3 is a sectional view taken along the line III-III of FIG. 1, FIG. 4 is a longitudinal sectional view showing the mold and the lead frame assembly in the middle stage of the resin injection, and FIG. 4 is a sectional view taken along the line VV, FIG. 6 is a longitudinal sectional view showing the mold and the lead frame assembly in the latter stage of the resin injection, and FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6, and FIG. Is a perspective view showing a completed resin-sealed semiconductor device, and FIG. 9 is a plan view showing a lead frame assembly. 2 ... Support plate, 3 ... External lead, 11 ... Lead frame assembly, 12 ... Resin encapsulant, 13 ... Mold, 14 ... Upper mold, 15 ... Lower mold, 16, 17, 18 …… Slide type, 25 …… Molding space.

Claims (1)

[Claims] 1. A lead frame assembly in which an electronic element and / or a circuit board is fixed to one main surface of a support plate of a lead frame, and external leads are arranged on one end side of the support plate. And a first cavity formed so as to obtain a molding cavity for resin-sealing both one main surface side and the other main surface side of the support plate.
And moving relative to the second main body mold and the first main body mold so as to come into contact with one main surface of the support plate, and inflow of the sealing resin into one main surface side of the support plate. And a first slide die formed so as to limit the position of the other main surface of the supporting plate by moving relative to the second slide die and the second main surface of the supporting plate. Preparing a molding die having a second slide die formed so as to allow the sealing resin to flow into the other main surface side of the support plate; Sandwiched by the second body type,
The other end side of the support plate is sandwiched by the first and second slide molds, and the distance between the other main surface of the support plate and the wall surface of the molding cavity facing the other main surface is the distance of the support plate. Arranging the lead frame assembly in the molding die so as to be smaller than a distance between one main surface and a wall surface of the molding cavity facing the one main surface, and the molding space is formed by the first slide die. Limiting the sealing resin injected from one side of the main surface of the support plate through the resin injection port leading to the place, the flow of the sealing resin to the other main surface side of the support plate of the support plate A step of injecting the sealing resin into the molding space in a state of being relatively strengthened relative to the flow of the sealing resin to one main surface side, and the supporting plate for the first and second slide molds. By a predetermined amount in a direction away from the one and the other main surfaces,
And a step of injecting a sealing resin into a void formed after the movement of the second slide die, the method for producing a resin-sealed electronic component.