JPH01208839A - Manufacture of resin sealed type electronic device - Google Patents

Abstract

PURPOSE:To improve heat-dissipating properties, and to form resin layers easily by respectively shaping the resin layer having excellent thermal conductivity on the other main surface side of a support plate and the resin layer having low thermal conductivity on one main surface side by a common molding die. CONSTITUTION:An outer lead for a chip-lead frame assembly is fitted into a groove 19 and held by a top force 14 and a bottom force 15 for a mold 11, and the underside of a support plate 2 is positioned under the state in which it is floated from the base of a molding void 16 at an interval L1. A first sealing resin 23 being fluidized by a pot 26 and having excellent thermal conductivity is pushed and injected to the whole or the greater part of the other main surface side of the support plate 2 from a gate 21, and a second sealing resin 24 having thermal conductivity lower than the first sealing resin 23 is pushed and injected to the whole or the greater part of one main surface side of the support plate 2. Two kinds of the sealing resins 23, 24 are formed easily by the common molding die 11, and a resin layer having superior thermal conductivity can be shaped on the underside side of the support plate 2.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is applicable to resin-sealed electronic devices such as resin-sealed power transistors and resin-sealed power center tap diodes having resin layers on both main surfaces. Regarding the manufacturing method.

[Conventional technology]

There is a resin-sealed electronic device in which substantially the entire surface of a support plate is covered with a resin-sealed body. This type of hand conductor device does not require an insulating sheet roller when attached to a heat sink or the like. However, since a part of the resin sealing body is also formed on the lower surface of the support plate, it is disadvantageous in terms of heat dissipation than a resin-sealed child conductor device of the type in which the lower surface of the support plate is exposed. Therefore, by making the resin sealant on the lower surface side of the support plate a thin layer with a thickness of about 0.5 mm, this disadvantage can be avoided. I'm doing less.

[The problem that the invention attempts to solve]

However, in resin-embedded electronic devices such as power transistors used in the 11th generation, it is necessary to improve heat dissipation even by a small amount. For this reason, simply forming a thin resin layer is insufficient. Further, there are limits to forming the resin layer thinly from the viewpoint of strength and moldability.

Therefore, in the past, the above requirements were met by using a blocking resin ya- with excellent heat dissipation (thermal conductivity).
However, the sealing resin used in this product has the disadvantage of being expensive, and also contains a large amount of hard material S such as crystalline silica to improve thermal conductivity, so the mold is 1% The gate part where the sealing resin is injected under pressure is significantly worn out. #Disadvantage of shortening the service life of J-valent moldsχ
have

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily and inexpensively manufacturing a resin-embedded electronic device having excellent heat dissipation properties.

[fil! Means for Solving Problem 1] To achieve the above object, the present invention provides 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 the lead frame. The process of
A molded hole Pj is formed so that both one main surface side and the other main surface side of the support plate can be pierced with resin.
A mold having a molding die having a distance of arranging the lead frame assembly in the mold so that the distance between the lead frame assembly and the threatening surface of the cavity is smaller than the distance between the lead frame assembly and the threatening surface of the mold, and the other main surface side of the support plate in the mold cavity lζ of the mold 10th sealing resin which has thermal conductivity in all or most of
% - Injected under pressure in a fluidized state, and after injecting the first sealing resin, a resin having lower thermal conductivity than the tenth sealing resin is applied to all or most of one main surface side of the support plate. The present invention relates to a method of manufacturing a resin-embedded electronic device including a step of press-injecting a second sealing resin in a fluidized state to obtain a resin-sealed body.

[For production]

In the above invention, when the first sealing resin having excellent thermal conductivity is injected onto the other main surface @ (lower surface side) of the support plate, the first sealing resin mainly composed of the first sealing resin has good heat dissipation properties. A resin layer is obtained. - One main surface of the support plate @ (upper surface side)
A resin layer with low heat dissipation properties mainly consisting of the second sealing resin is obtained.

Since these two types of fat layers are formed using a common mold, it is possible to suppress an increase in the cost of the mold and a drastic increase in the number of molding steps. Resins with good thermal conductivity are generally not expensive and wear out molds. However, in the present invention, only a part of the resin sealing body is made of a resin layer with good thermal conductivity, so that it is possible to suppress an increase in cost and wear of the bottom mold.

〔Example〕

With reference to FIGS. 1 to 11, a method for displaying a resin-sealed power transistor according to an embodiment of the present invention will be described.

First, a lead frame 1 shown in FIG. 11 is prepared. This lead frame 1 includes a support plate 2 and one end lζ of the support plate 2.
It has external leads 3 arranged, tie bars 4 and connecting strips 5 that connect the external leads 3 in parallel. In actuality, the lead frame 1 is designed to take a multiplex element in which the first support plate 2 is mounted.

Note that 6 is a hole for inserting a screw used for external dissection and attachment to a heat sink. A semi-solid chip 7, that is, a transistor or a static chip is fixed to the lead frame 1 through solder (not shown) by a well-known die bonding method.

Further, thin lead wires 8 are connected by a well-known wire bonding method. The thin lead wire 8 electrically WWCs the conductor chip 7 and the external lead 3. With this 71, the chip
A lead frame assembly 9 is obtained. Hereinafter, the chip/lead frame assembly 9 will be simply referred to as a lead frame assembly. The three-dimensional lead frame Ji11 9 is covered with a resin sealant 10 as shown by the skin gland in FIG. In addition.

The tree PIFIN stopper 10 is made of resin of class 2a, as will be clear from the description below.

In order to form the m-lipid sealing body 10 by the transformer 7 amolding method, the lead frame assembly 9 is placed in a mold 11 as shown in FIG. The mold 11 has an upper mold 14 and a lower mold 1
In addition to 5, the first and second slide molds 12.13Y1j
are doing. The slide molds 12 and 13 are movable up and down relative to the upper mold 14. The upper mold 14 has a recess 16
A cylindrical convex ff1s17 is formed f, and a convex If
! 117 is inserted into the hole 61 of the support plate 2. however,
Since the convex portion 17 is spaced apart from the peripheral surface of the FF 3 of the hole 6 by &'L, a part of the resin sealing body 10 is formed on the inner peripheral surface of the hole 60. The lower mold 15 has a recess 18. Groove 19 for inserting external lead 3
° Runner (resin flow path) 20. Gate (resin injection port)
21 are provided. By closing the upper mold 14 and the lower mold 15, a molding cavity 22 corresponding to the resin sealing body 10 is formed in the mold 11 through the concave portion 16 and the convex portion 17I.

When the lead frame assembly 9 is placed, the external leads 6 are held together by the upper die 14 and the lower die 15 with the grooves 19 # interlocked.

Therefore, the lower surface of the support &2 is positioned in a state where it is floating at a thin distance L1 of about 0.5 mm from the bottom surface of the molded blank PJT 16. Next, the slide mold 12 is lowered and its bottom surface is molded 9. The support plate 2 is disposed so as to be spaced apart from the bottom surface of the support plate 16 by an interval equal to the above-mentioned thin interval L1 plus the thickness of the thick portion of the support plate 2.

Therefore, even if the support plate 2 has a raised end on the side opposite to the side to which the external leads 3 are connected.

The opposite end S is pushed by the slide mold 12,
The distance between the lower surface of the support plate 2 and the bottom surface of the molding cavity &22 is a stably thin distance Ll'! 'keep. In this embodiment, the lead frame assembly 9 is arranged, and after the upper mold 14 and the lower mold 15 are closed, it is advanced to the slide mold 12.13'l' upper mold 14 and the first
It was placed in the position shown in the figure.

However, the slide mold 12.13 may be projected from the upper mold 14 into the molding cavity 22 before the upper mold 14 and the lower mold 15 are closed.

Next, as shown in FIG. 8, a resin block 2 is formed in which the first sealing resin 23 and the second sealing resin 24 are integrated into a cylindrical shape.
5 to bot C1f in Figure 1! Pour into B fat inlet) 26. The first restraining resin 26 on the lower side of the resin flock 25 is
Contains crystalline silica etc. i! The 1 m 2 stopper resin 24 contains less IIK of hard substances such as crystalline silica than the first stopper resin 26, and has low thermal conductivity. The resin cooker 25 is softened by ultrasonic heating or the like, and then put into the pot 26 with the first restraining resin 23 facing downward. pot 2
By preheating the resin block 6 and the mold 11 to about 160° C., the resin block 25 placed in the pot 26 is melted and fluidized.

Next, the resin block 25 is pressed by a plunger 27 disposed in a rotatable manner in the pot 26, and the first and second sealing resins 23.2 which have been fluidized are pressed against the resin block 25.
4 is sent to the runner 20 in the 111st order. In addition, pot 2
Since the diameter of the resin block 6 and the diameter of the resin block 25 are in the opposite direction, the first and second sealing resins 23 and 24 are not mixed significantly and are supplied to the resin block 111 in a separated state. . In this embodiment, the pot 26 is connected to two molding cavities 15T22 (one not shown) arranged symmetrically with respect to the ar resin block 25, so that the two resin-sealed transistors are resin-sealed. It is formed to a size that allows the body 10 to be obtained.

In order to inject the first restraining resin 23 into the lower side of the support plate 2, the first and second slides ff112 are moved as shown in FIG.
．． 13 is lowered so that it touches the top surface of support &2. The first slide mold 12 has a notch 12a as shown in FIG.
and a pair of legs 12b.

It has 12 cV. On the other hand, the second slide mold 13 is
As shown in the figure, it does not have a notch. First and second slides fJ! 12.13 each drive 28.2
9 is combined 4. Each of the four can be moved up and down independently.

As is clear from FIG. 1, a protrusion 14a provided on the upper die 14 is inserted into the notch 12a of the first slide die 12. As shown in FIG. The lower surface of the protrusion 14a forms a gap equivalent to the thickness of the resin sealing body 10 with respect to the stop surface of the support plate 2. Therefore, the protrusion 14a fills only a part of the notch 12a of the first slide mold 12.

In this embodiment, the cage 21 is disposed below the upper surface of the support plate 2.
Therefore, the first and 20th slide molds 12
．． In the state shown in FIG. 1 where the lower end of the gate 13 is in contact with the support plate 2, the gate 21 is connected to the lower side of the support plate 2, but not to the upper side. When the first runner 27 is pressed in the state shown in FIG.
0 and the gate 21 are injected into the lower side of the molding cavity 22, that is, the lower side of the support plate 2. #! 1 sealing resin 23V support 2
When W pressure is injected to the lower side, a force is applied in the direction of lifting the support "4!124" or "rL," but since it is blocked by #!1 and the second slide mold 12.13, the movement of the support plate 2 is Note that since the distance between the side surface of the support plate 2 and the wall surface of the H-shaped cavity 22 is approximately 0.8 mm, the resin will not flow from the bottom of the support plate 2 to the top through the side surface. The flow is limited to 11. The first sealing resin is mainly injected into the lower side of the support plate 2. Also.

Although not shown in FIG. 1, the runner 20. on the right 1111 of pot 26. Gate 21. A forming cavity 22 and an in-shape are also provided to the left of the center of the box 26'. Since the lengths of the runners 20 leading to the two molding cavities 22 are the same, the resin is injected at the same rate.

If it is found from the position of the plunger 270 that the lower side of the temporary support is filled with the tenth sealing resin 23.

The second slide mold 13 is moved upward as shown in Fig. 2 and Fig. 5. Since the first slide die 12 is not moved, upward movement of the support plate 2 is prevented. The resin injected from gate 21 is J1! M4 protrusion s 1
4a and the second slide mold 16 to flow into the upper side lζ of the support plate 2.

Note that the second sealing resin 24 or the first
The remainder of the zero gripping resin 23 and the second sealing resin 24 flow in.

When the upper part of the support plate 2 is filled with the second sealing resin 24, the first slide mold 12 is moved upward to the third stage and as shown in FIG. This causes the leg 1'lS12b of the first slide W12.

12c becomes a void, which is also filled with the second sealing resin 24. In the case of m3 prisoner and the state shown in Fig. 6, the support plate 2 is #!
Although the first and second slide molds 12 and 13r are not positioned, the lower side of the support plate 2 is first filled with the first sealing resin 26 (and most of the upper side of the support plate 2 is also filled!2 Since the sealing resin 24 is filled, vertical movement of the support plate 2 hardly occurs.After the injected resin has solidified, the lead frame assembly 9 is taken out from the metal FF111, and the tie bars and connecting strips 5 are removed. By removing it, the resin sealing body 1 consisting of the ml and the second sealing resin layers 23a and 24a as shown in the seventh column.
01ζ, a resin-sealed transistor in which all parts except the external lead 3 are sealed is obtained. In addition.

The sealing resin layer 23a on the lower surface side of the support plate 2 mainly consists of the first
The sealing resin layer 24a on the upper surface side of the support plate 2 is mainly composed of a second sealing resin layer 23a having a lower thermal conductivity than the first sealing resin layer 23a. This is a resin layer made of sealing resin 24. Since both the ml and second sealing resin layers 23a and 24a are made of epoxy resin, they are tightly adhered to each other.

The non-embodiment has the following effects.

+11 Different pricking resin layers 23a, 24aY can be easily formed on the lower surface side and the upper surface side of the support plate 2.

(2; The resin layer 23a with excellent thermal conductivity can be formed on the lower surface side of the support plate 2. Therefore, it is possible to provide a resin-sealed semiconductor device tltyr with excellent heat dissipation.

131 The resin layer 24a on the upper surface side of the support plate 2 does not contribute much to the radiation of heat generated by the semiconductor chip 7.

In general, low-cost resins with poor thermal conductivity can be used. Therefore, a low-cost resin-sealed semiconductor device can be provided.

(The first sealing + h resin 23, which contains a large amount of silica etc. that wears out the W11, forms only a portion of the resin sealing body 10, so the amount used is reduced.

Wear of the gate 21 and the like of the mold 11 can be reduced and the service life can be increased.

(5) The lengths of the runners 20 that extend from the common bot 26 to the molding spaces 22 of the counts are equal.

Therefore, the first injected into each forming air PJr22
The amounts of the sealing resin 26 are approximately equal. The same applies to the second sealing resin 24. Therefore, there is no variation in heat dissipation characteristics, etc.

(61 The lengths of the runners 20 sharpened from the pot 26 are equal. Therefore, the amount of stopper resin injected into the molding cavity 22 depends on the height of the plunger 27. .13 is pulled out at 1 runge 2
Can be controlled based on the height position of 7, sliding type 1113
Easy to control movement.

(7) Since the first and second slide molds 12.13 are used, it is possible to separately inject resin into the lower and upper sides of supports L & 2 while keeping the height position of support plate 2 constant. .

[Modified example]

The invention is not limited to the embodiments described above.

For example, the following transformations are possible.

+11 As shown in the 12th prisoner, a part of the gate 21 may be located above the top surface of the support plate 2, and the remaining part may be located below the top surface. In this case, since th P'jr where MIIIS 12b and 12C of the i-th slide mold 12 are located directly communicates with the gate 21,
Even if the slide die 12 is pulled out slowly.

Legs 12b and 12c of slide mold 12 @1. The resin can be reliably injected into the places where the resin has been removed.

(2) The tenth sealing resin 26 and the second sealing resin 24 may be separated by one part each from the resin block 25. In this case, first the first sealing resin 23 is injected, and then A second sealing resin 24 is injected.

(3+ The launch 20 connected to the gate 21 is divided into two, and the first sealing resin 2 is placed in the pot connected to one of the launches.
6, and the second sealing resin 24 may be added to the pot connected to the other lunch.

+41 As shown in the 13th factor, goo for the first restraining resin 26) 2.1a, the runner 20a and the second restraining resin 2
The runner 21b and the runner 20b may be provided separately. In this case, a gate 21a for the first restraining resin 26 with excellent thermal conductivity is provided below the upper surface of the support plate 2, and a gate 21b for the second restraining resin 24 is provided on the support plate 2.
It is best to provide it above the top surface of the First restraining resin 2
6 injection σ), the gate 21b for the second restraining resin 24
is closed with a second slide mold 16. With this? t
.

The two runners 20a and 20b may be connected to the same port or may be connected to separate ports. (51 Only the second slide mold 13 may be used.

In this case, in order to securely fix the support plate 2, the upper mold 14
Use a mold in which the lower mold 15 is provided with a pin for fixing the support plate 2, or use a positioning lead from the end of the support plate 2 opposite to the connecting slanted side of the outer lead 3. It is desirable to use a derived lead frame.

(61 The means for separating the resin flowing to the upper surface side and the lower surface side of the support plate 2 does not need to be the one using the slide mold 12.13. For example, as shown in FIGS. 14 and 15 (two Gates 21 a and 21 b are provided, and a protrusion 30 is provided near the gate 21 b of the upper die 14 , so that the resin injected into the lower gate 21 a is difficult to flow to the upper surface due to the protrusion 30 and mainly flows to the lower surface. Toryu [5. Upper Goo] 21 b
The resin injected from the base plate 2 may be allowed to flow smoothly to the upper surface of the support plate 2 without being restrained by the protrusion fB530.

(71 Extend the positioning lead from the end of the support plate 2 on the opposite side to the side where the external lead 3 is connected.

A lead frame in which the support plate 2 is supported on both sides by the mold 11 can also be used.

(Thermosetting resins such as 81 epoxy resins (not limited to this) can also be applied when using thermoplastic resins.

(Don't begrudge 91 transistors.) It can also be applied to electronic devices such as diode devices, composite semiconductor devices, and electronic devices.

[Effects of the Invention] As described above, according to the present invention, it is possible to easily manufacture a resin-side stop type electronic device that has excellent heat dissipation properties and is inexpensive. Furthermore, wear of the molding die can be reduced.

[Brief explanation of the drawing]

FIG. 1 shows the relationship between the mold and the chip/lead frame assembly used in the manufacture of a resin side-stop type transistor and star according to an embodiment of the present invention, and is shown in a section corresponding to T-1M in FIG. 11. A sectional view shown. FIG. 2 is a sectional view showing a state in which the second slide mold of the mold shown in FIG. 1 has been moved upward. FIG. 3 is a sectional view showing a state in which the first and second slide molds of the mold shown in FIG. 1 have been moved upward. FIG. 4 is a cross-sectional view of a portion corresponding to the IV-rV line 6r in FIG. 1. FIG. 5 is a sectional view of a portion corresponding to the V-line in FIG. 2. FIG. 6 is a sectional view of a portion corresponding to the W-%I line in FIG. 3. FIG. 7 is a partially cutaway sectional view showing a resin-sealed transistor with light extraction. FIG. 8 is a perspective view showing a resin block to be put into the pot of FIG. 1. FIG. 9 1 is a perspective view showing the first slide mold. FIG. 10 is a perspective view showing the second slide mold. Figure 11 is 11i! ! A plan view showing the lead frame Japanese style of J. FIG. 12 is a sectional view of a portion opposite to FIG. 1 showing a modified example of the mold. FIG. 16 is a sectional view of a portion corresponding to FIG. 1 Cζ showing another modification of the mold. FIG. 14 is a cross-sectional view of a portion corresponding to FIG. 1 showing a modified example of the history of the mold. FIG. 15 is a sectional view showing the XV-IV gland of FIG. 14. 1... Lead frame, 2... Support plate, 7... Chip. 9... Lead frame assembly, 10... Resin sealing body. 11... Mold, 12... First slide mold, 13
...Second slide mold, 14...Upper mold, 15...
- Lower mold, 22... R-shaped nitrogen, 26... first sealing resin, 24... second restraining resin. Agent Nori Takano Figure 4 Figure 5 Figure 11-E

Claims (1)

[Scope of Claims] [1] A step of preparing 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 one main surface of the support plate. A molding mold having a molding cavity formed so that both the side and the other main surface side can be resin-sealed is prepared, and the other side of the support plate and the molding cavity opposite thereto are prepared. arranging the lead frame assembly in the molding mold such that the distance between the lead frame assembly and the wall surface of the molding cavity is smaller than the distance between one main surface of the support plate and the wall surface of the molding cavity facing thereto; , a first sealing resin having excellent thermal conductivity is press-injected in a fluidized state into all or most of the other main surface side of the support plate in the molding cavity of the mold; After injecting the first sealing resin, a second sealing resin having lower thermal conductivity than the first sealing resin is applied to all or most of one main surface side of the support plate.
A method for manufacturing a resin-sealed electronic device, comprising the step of press-injecting a fluidized sealing resin to obtain a resin-sealed body.