JPH0521644A - Manufacture of resin-sealed electronic component - Google Patents

Abstract

PURPOSE:To provide a resin-sealed electronic component of a structure, wherein a crack is not generated in a resin sealed body at the time of removing support leads by pulling them. CONSTITUTION:A lead frame assembly, which is provided with support leads 8 each having a first narrow part 8a, a second narrow part 8b wider than the part 8a and a wide part 8c further wider than the 8b in order from the side of a support plate, is prepared. Outer leads and the leads 8 are held by a molding die and a sealing resin is injected and cured in a molding open space to form a resin sealed body. After that, a tensile force is applied to the leads 8 and the lead 8 is removed on both sides of a through hole 8g and on the inner side of the resin sealed body. As the lead 8 is provided with the first and second narrow parts, the extension of the lead 8 is increased when the pulling force is applied and a deforming force which is added to the resin sealed body can be reduced. Moreover, a plurality of stress concentration parts are generated in the resin sealed body by the first and second narrow parts and the most concentrated stress can be reduced. As a result, a stress, which is generated in the resin sealed body at the time of drawing of the lead 8, is relaxed and the generation of a crack in the resin sealed body is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a resin-sealed electronic component.

[0002]

2. Description of the Related Art A method is known in which an external lead and a supporting lead, which are led out from a supporting plate also serving as a heat radiating plate, are sandwiched by a mold to float the supporting plate in a molding cavity and resin-mold it. After the resin molding, the support lead can be pulled in the pull-out direction to be broken, and the broken portion of the support lead can be provided inside the resin sealing body. This method has an advantage over the conventional method of cutting the support lead along the interface of the resin encapsulant, which significantly increases the creepage distance between the support lead and the external heat radiator and improves the dielectric strength voltage. Further, since the cut end face of the support lead can be easily covered by filling a resin such as rubber into the hole of the resin sealing body formed after the extraction of the support lead, it is attracting attention as a novel molding method. The present applicant has also tried this method and confirmed that a sufficiently large withstand voltage can be secured.

[0003]

However, it has been found that when the support lead is pulled out and fractured, the resin sealing body in the vicinity of the support lead is apt to crack, and when the crack occurs, the moisture resistance of the electronic component is deteriorated. In order to solve this problem, the present applicant has tried to devise the shape of the small cross-sectional area part which becomes the pull-out fracture part by combining various combinations of through holes, notches, grooves, etc.
The result was not sufficiently satisfactory.

Therefore, an object of the present invention is to provide a method of manufacturing a resin-sealed type electronic component in which a crack does not occur in a sealing resin when a support lead is pulled out.

[0005]

A method for manufacturing a resin-sealed electronic component according to the present invention comprises a support plate, external leads provided on one end side of the support plate, and the other end part of the support plate. And a support lead provided on the side of the support plate, the support lead having a first narrow portion, a second narrow portion wider than the first narrow portion, and a second narrow portion in order from the support plate side. And a second narrow portion, each of which is formed by a pair of cutout portions formed on opposite side surfaces of the support lead so as to face each other, A lead frame assembly having an inclined portion or a circular arc portion that widens toward the support plate side at a boundary between the first narrow portion and the support plate, and a through hole is formed in the first narrow portion. And the external lead and the support lead are sandwiched by the molding die, and the support plate floats in the molding cavity of the mold. Narrow portion of the steps of the part of the wide portion of the second narrow portion and the support leads disposed in the molding cavity,
A step of injecting a sealing resin into the molding cavity and then curing the resin to form a resin sealing body, and applying a tensile force to the support leads to form the support leads on both sides of the through hole and of the resin sealing body. And a step of breaking inside.

[0006]

Since the support lead is provided with the first narrow portion and the second narrow portion, the extension of the support lead increases when a tensile force is applied to the support lead, and the support lead is added to the resin sealing body. The deformation force can be reduced. Further, the first narrow portion and the second narrow portion form a plurality of stress concentration portions for the resin sealing body, and the maximum concentration stress generated in the resin sealing body can be reduced. Therefore, the stress generated in the resin encapsulant at the time of pulling out the support lead is relieved, and the occurrence of cracks in the resin encapsulant can be prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention applied to manufacture of a power transistor device will be described with reference to FIGS.

First, a lead frame assembly (1) as shown in FIG. 1 is prepared. The lead frame assembly (1) includes a plurality of support plates (2) and one end (2) of the support plate (2).
c) has an external lead (3) arranged on the side. A semiconductor chip (4) is fixed to one main surface (2a) of the support plate (2) via solder (not shown), and between the semiconductor chip (4) and the external lead (3). It is electrically connected by a thin lead wire (5). The outer leads (3) are connected in parallel by the tie bars (6) and the outer lead connecting strips (7). Support leads (8) from the other end of the support plate (2)
Are led out and are connected in parallel by a support lead connecting section (9).

As shown in FIG. 2, the support lead (8) has a first narrow portion (6a) and a second narrow portion wider than the first narrow portion (8a) in order from the support plate 2 side. It has a wide portion (8c) wider than the portion (8b) and the second narrow portion (8b). The first narrow portion (8a) and the second narrow portion (8b) are each formed by a pair of notches formed on both sides of the support lead (8). The notch forming the first narrow portion (8a) is the second
Of the first narrow portion (8a), the first narrow portion (8a) is narrower than the second narrow portion (8b), and the first narrow portion (8a) is narrower than the second narrow portion (8b). ) And the second narrow portion (8b) are provided with a step portion (8d). Further, a step portion (8a) is also provided between the second narrow portion (8b) and the wide portion (8c). In addition,
The depths of the notches for forming the first narrow portion (8a) and the second narrow portion (8b) are equal on the left and right sides. Further, an inclined portion (8f) is provided at the boundary between the first narrow portion (8a) and the support plate (2). Furthermore, the first narrow portion (8a)
A through hole (8g) is drilled in this.

Next, the lead frame assembly (1) is placed on a molding die (10) for transfer molding as shown in FIG. 3 in order to form a resin sealing body by the well-known transfer molding method. The outer lead (3) and the support lead (8) are sandwiched at the interface between the upper mold (11) and the lower mold (12), and the support plate (2) of the lead frame assembly (1) is molded into the cavity (25). ) Is positioned in a floating state. The fluidized sealing resin (29) is injected into the molding cavity (25) through the runner and the gate while the support plate (2) is positioned. In this case, since the support plate (2) supported by both ends is firmly held, the resin for sealing (2
It does not tilt under the pressure of 9). After the sealing resin (29) filled in the molding space (25) is cured, the lead frame assembly (1) is taken out of the molding die (10).

Subsequently, when a tensile force is applied to the lead-out portion of the support lead (8) of the lead frame assembly (1) to break the support lead (8) on both sides of the through hole (8g), the support lead (8) (8h) is formed inside the resin sealing body (31).

According to this embodiment, the following effects can be obtained.

(1) When the support lead (8) is pulled out and broken, the resin sealing body (31) near the support lead (8) is not cracked. The reason for this is considered as follows.
That is, since the support lead (8) is provided with the first narrow portion (8a) and the second narrow portion (8b), when the support lead (8) is applied with a tensile force, the support lead (8) The growth of
The deformation force applied to the resin sealing body (31) can be reduced. In addition, the first narrow portion (8a) and the second narrow portion (8a)
By b), a plurality of stress concentration portions for the resin sealing body (31) are formed, and the maximum concentration stress generated in the resin sealing body (31) can be reduced. Therefore, the stress generated in the resin sealing body (31) at the time of pulling out the support lead (8) is relieved, and the generation of cracks in the resin sealing body (31) can be prevented. The support lead (8) is the support plate (2).
Since the width is gradually widened from the side, the resin sealing body (3) separated from the support plate (2) when the support lead (8) is pulled out.
1) does not rub against the side surface of the support lead (8) on the support plate (2) side. In addition, the first narrow portion (8a) and the second narrow portion (8a)
Since b) is formed by notches from both side surfaces of the support lead (8), the above operation can be stably obtained even if the support lead (8) is pulled while being inclined left and right from the lead-out direction.

It should be noted that, in the experiments conducted by the present inventor, even if the first narrow portion (8a) is not provided, the formation of the hole (8g) has a decisive effect on the cross-sectional shape of the support lead (8). It was confirmed that the support lead (8) could be pulled out and ruptured, but that the resin sealing body (31) was likely to crack. Also, the first
Instead of the notch forming the narrow portion (8a) and the second narrow portion (8b), the first narrow portion (8a) and the second width without forming the step portion (8d) It was confirmed that even when a continuous taper was formed between the narrow portion (8b) and the resin sealing body (31), cracks were likely to occur.

(2) Also, in this embodiment, the inclined portion (8f)
As a result, a large holding force of the support lead (8) with respect to the support plate (2) can be obtained. Therefore, the support plate (2) does not tilt due to the external force applied during transportation or the resin injection pressure during resin molding.

(3) There is an additional effect that the creepage distance between the outer wall of the resin encapsulant (31) and the fractured portion of the support lead (8) increases.

The embodiment of the present invention is not limited to the above embodiment, and the following modifications are possible.

(1) The hole (8g) may extend to the second narrow portion (8b).

(2) The inclined portion (8f) may be arcuate.

(3) In the above-mentioned embodiment, an example applied to the manufacture of the power transistor device of the present invention has been shown, but it will be understood that the present invention can be applied to other electronic components.

[0021]

According to the present invention, it is possible to obtain a resin-sealed electronic component having a large withstand voltage without cracks in the resin-sealed body when the support lead is pulled out.

[Brief description of drawings]

FIG. 1 is a plan view of a lead frame assembly used for manufacturing a power transistor device according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view showing a main part of the lead frame assembly of FIG.

FIG. 3 is a cross-sectional view taken along the line I-I of FIG. 1 showing a state where the lead frame assembly is mounted on the molding die.

FIG. 4 is a sectional view taken along line II-II in FIG.

FIG. 5 is a perspective view of a power transistor device manufactured according to the present invention.

[Explanation of symbols]

(1). ． ． Lead frame assembly, (2). ． ． Support plate, (3). ． ． External lead, (8). ． ． Support leads, (8a). ． ． First narrow portion, (8b). ． ． Second
Narrow part of (8c). ． ． Wide part, (8f). ． ． Inclined part, (8g). ． ． Through-hole, (10). ． ． Molding die,
(twenty five). ． ． Molding void, (29). ． ． Sealing resin,
(31). ． ． Resin encapsulant

Claims (1)

1. A support plate, an external lead provided on one end side of the support plate, and a support lead provided on the other end side of the support plate. , The support lead has, in order from the support plate side, a first narrow portion, a second narrow portion wider than the first narrow portion, and a wide portion wider than the second narrow portion. And the first narrow portion and the second narrow portion are both formed by a pair of notches formed on opposite side surfaces of the support lead in directions opposite to each other. At the boundary between the narrow portion and the support plate, there is an inclined portion or an arc portion that widens toward the support plate side, and the first narrow portion has a through hole formed therein. A step of preparing a solid body, and sandwiching the external lead and the support lead with a molding die,
Arranging the support plate, the first narrow portion, the second narrow portion and a part of the wide portion of the support lead in the molding cavity while the support plate is floating in the molding cavity of the mold; , A step of injecting a sealing resin into the molding cavity and then curing the resin to form a resin sealing body, and applying a tensile force to the support lead so that the support lead is provided on both sides of the through hole and A step of breaking inside the resin encapsulant, and a method for producing a resin-encapsulated electronic component.