JPH02122634A - Manufacture of resin sealed electronic part - Google Patents

Abstract

PURPOSE:To form a part of a resin-sealed unit also on another principal surface of a support plate by a method wherein an external lead is interposed by a mold, a first movable mold is made in contact with one of principal surfaces of another end of a support plate while a second movable mold is made into contact with the other principal surface of another end of the support plate, and fluid sealing resin is injected from a resin inlet port into a mold cavity. CONSTITUTION:The other end of a support plate is interposed between first and second movable molds 20, 22 until an almost whole molding cavity 27 is filled with sealing resin 29. This can securely prevent the support plate 2 from tilting during resin molding, thereby efficiently forming a thin resin layer having approximate uniform thickness over an entire area on another principal surface 2b of the support plate. More of the sealing resin 29 is injected in the said principal surface 2b of the support plate where the sealing resin cannot be easily injected. This enables well-balanced injection of the sealing resin 29 into one of principal surfaces 2a and the other principal surface 2b of the support plate 2, thereby excellently forming a resin-sealed unit 31.

Description

[Detailed Description of the Invention] Field of the Invention The present invention relates to a method of manufacturing a resin-sealed electronic component, and more specifically, a resin-sealed electronic component in which a part of the resin-sealed body is also formed on the lower surface of a support plate. The present invention relates to a method of manufacturing a fixed type electronic component.

There is a resin-sealed semiconductor device in which a portion of the resin-sealed body is also formed on the lower surface side of the support plate that should be disassembled in the future. This type of semiconductor device has the advantage of being able to be mounted to an external heat sink without using an insulating plate, but in terms of heat dissipation, it is better than a resin-sealed semiconductor device with the bottom surface of the support plate exposed. It is disadvantageous.

therefore.

In order to improve heat dissipation as much as possible, it is necessary to form the resin layer on the lower surface side of the support plate as thin as possible. By the way, in order to form a thin resin layer on the bottom side of the support plate, the support plate must be placed at a narrow distance from the bottom of the molding cavity, and the sealing resin must be injected into this narrow space. . For this reason, the sealing resin was not properly injected, resulting in molding defects. Therefore, in Japanese Patent Application Laid-Open No. 60-257529, a convex portion was provided on the upper surface of the molding cavity, and this convex portion A method of resin molding while suppressing the flow of sealing resin toward the upper surface of a support plate is disclosed. According to this manufacturing method, the flow of the sealing resin toward the lower surface of the support plate can be relatively strengthened, so that the resin layer on the lower surface of the support plate can be formed relatively well. By the way, in the above manufacturing method, in order to float the support plate at a predetermined distance from the bottom of the molding cavity during resin molding, the support plate is fixed with a pin that protrudes into the molding cavity, or,
The support leads extending from the support plate are held between molds,
It is necessary to fix the support plate.

For this reason, pin holes were formed in the completed resin sealing body, and broken surfaces of the support leads were exposed, making it impossible to use it in applications requiring severe dielectric strength. Therefore, JP-A-60-
Japanese Patent No. 130129 discloses a method of forming a resin-sealed body by fixing a support plate with a movable pin that is provided to freely move forward and backward with respect to a mold. According to this method, by continuously injecting the sealing resin after the movable pin moves, the sealing resin can also be injected into the void formed after the movable pin moves.
It seems possible to form a resin-sealed body without pin holes. However, it was difficult to control the movement timing of the movable pin, and the problem could not be solved satisfactorily.

That is, if the movable pin is moved too early, the movable pin will be released from being held down by the movable pin before the support plate is fixed by the sealing resin, and the support plate will be tilted. In addition, if the movable pin is moved too late, the fluidity of the sealing resin around the movable pin will be impaired, and the sealing resin will not be able to be injected into the empty space after the movable pin has moved, resulting in a pin hole. It will happen.

Therefore, the present invention solves the above problems, allows a thin resin layer to be satisfactorily formed on the lower surface of a support plate, and easily produces a resin-sealed electronic component in which the entire surface of the support plate is covered with a resin sealant. The purpose is to provide a manufacturing method.

In order to solve the problem, there is a method of manufacturing a resin-sealed electronic component according to the present invention, in which substantially the entire surface of a hand support plate is covered with a resin sealant.

An electronic component assembly having a support plate having an electronic element fixed to one main surface, an external lead connected to one end side of the support plate, a molding cavity formed therein, and first and second movable parts. For molding, the mold is provided to be movable forward and backward with respect to the molding cavity, the first movable mold is provided with a notch, and a resin injection port having one or more openings with respect to the molding cavity. The process of preparing a mold and holding the external lead between molds,
The first movable mold is brought into contact with one main surface on the other end side of the support plate, and the second movable mold is brought into contact with the other main surface on the other end side of the support plate. The distance between the main part of the other main surface of the plate and the wall surface of the molding cavity opposite thereto is smaller than the distance between the main part of one main surface of the support plate and the wall surface of the molding cavity opposite thereto. The steps include placing the electronic component assembly in a mold, blocking a portion of the resin injection port with the first movable mold and the second movable mold, and closing the support plate with the first movable mold. While restricting resin injection into the molding cavity on the one main surface side, fluidized sealing resin is injected from the resin injection port through the notch to the one main surface side of the support plate of the molding cavity, and the resin A step of injecting fluidized sealing resin from the injection port to the other main surface side of the support plate in the molding cavity, and after the support plate is substantially fixed by the sealing resin injected into the molding cavity, The method includes the steps of separating the first and second movable molds from the support plate, and further injecting a sealing resin into the molding cavity from the resin injection port.

■According to the present invention, since the first movable mold suppresses the flow of the sealing resin toward one main surface side of the support plate, the flow of the sealing resin toward the other main surface side of the support plate is suppressed. The resin flow can be relatively strengthened. Therefore, the balance between the sealing resin injected onto one main surface side of the support plate and the other main surface side of the support plate is good, and a thin resin layer with no voids etc. is formed on the other main surface side of the support plate. can be formed well. In addition, since the other end side of the support plate is fixed by the first and second movable molds until the support plate is almost fixed by the sealing resin injected into the molding cavity, the injection of the sealing resin It is possible to completely prevent the support plate from tilting during the process. Further, a part of the resin injection port is closed with the first movable mold.

Since the other part of the resin injection port is closed by the second movable mold, the void formed by the movement of the first and second movable molds is filled with the sealing resin supplied from the resin injection port. This allows for reliable and complete filling.

A method of manufacturing a resin-sealed semiconductor device according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 6.

First, an electronic component assembly (1) which is a lead frame assembly as shown in FIG. 5 is prepared. The lead frame assembly (1) has a plurality of support plates (2) and an external lead (3) disposed on one end (2C) side of the support plate (2). A semiconductor chip (4) is fixed to one main surface (2a) of the support plate (2) via solder (not shown), and there is no space between the semiconductor chip (4) and the external leads (3). It is electrically connected by a thin lead wire (5).

The external leads (3) are connected in parallel by tie bars (6) and external lead connecting strips (7). Support leads (8) are led out from the other end of the support plate (2) and connected in parallel by support lead connection strips (9). Unlike the conventional example, the support lead (8) and the support lead connection strip (9) are cut and removed before the transfer molding process described later. In the assembly process up to the transfer molding process, the lead frame assembly (1) is handled with the support plate (2) fixed on both sides by the external lead (3) and the support lead (8). 1) It does not cause any bending that would interfere with the above.

Next, in order to form a resin sealing body by the well-known transfer molding method, the lead frame assembly (1) is placed in the first
As shown in the figure, it is placed in a molding die (molding die) (10) for transfer molding. The molding mold (10) has an upper mold (11) and a lower mold (12), and the upper mold (11) has a cylindrical convex part (13), a gate (14), and a gate (14).
A runner (15) is formed leading to the lower mold (12).
) has a groove (40), a gate (16), a runner (17) leading to the gate (16), a gate (18), a gate (1B
) is formed with a runner (not shown). (14), (16), and (18) are resin injection ports.

Furthermore, the molding die (10) of this example has an upper mold (11).
A first movable mold (20) that can be driven up and down in a guide hole (19) provided in the lower mold (12), and a second movable mold that can be driven up and down in a guide hole (21) provided in the lower mold (12). Movable type (22
). The first movable mold (20) and the second movable mold (22) are connected to drive devices (23) and (24), respectively, and drive control is performed thereby.

Inside the molding mold (10) are an upper mold (11) and a lower mold (12).
By closing the recess (
25) and a recess (26) provided in the lower mold (12) form a molding cavity (27) corresponding to the resin-sealed body to be formed. As shown in FIG. 1, the lead frame assembly (1) is held between an upper mold (11) and a lower mold (12) with the external leads (3) fitted into the grooves (40).

Next, the first and second movable molds (20) and (22) are moved downward and upward, respectively, and their lower surface (20d) and upper surface (22d) are respectively attached to the other end of the support plate (2) (
2d) is brought into contact with the first main surface (2a) (upper surface) and the other main surface (2b) (lower surface). As a result, the other end (2d) side of the support plate (2) moves toward the movable mold (20) (2).
2), and the support plate (2) has one end (
2c) side and the other end (2d) side are temporarily supported.

Therefore, the other main surface (2b) of the support plate (2) is spaced a small distance L from the bottom surface of the molding cavity (27) over the entirety.
(approximately 0.4 m) apart. In this embodiment, after closing the molding mold (10), the movable mold (20) is
(22) was moved so as to plunge it into the molding cavity (27), but the movable mold (20) (22) was moved in advance into the molding cavity (27).
27) and then the mold (10)
may be closed.

Next, the pot (resin inlet) leading to the molding cavity (27)
A sealing resin (29) that has been slightly softened by high-frequency heating or the like is added to (28). The pot (28) has a molded cavity (
Similar to the molding die (10) constituting the portion 27), the sealing resin (29) is heated to a temperature that is fluidized. Therefore, the sealing resin (29) put into the pot (28) is pressed by the plunger (push mold) (30) provided in the pot (28) so as to be movable up and down, so that the sealing resin (29) is pressed by the gate (14). )(16)(18) into the molding cavity (27).

The first movable mold (20) has a notch (2) as shown in FIG.
0a), and a pair of legs (20b) (20C) are formed on both sides of the notch (20a). Further, the second movable mold (22) is also a plate-shaped mold having a notch (22a) and a pair of legs (22b and 22c), as shown in FIG. The first and second movable molds (20
) (22) has one main surface in contact with the creeping surface of the molding cavity (27) on which the gates (14), (16), and (18) are provided. Legs (20b) of the first movable mold (20) (
20c) is smaller than the width of the gate (14),
Therefore, the gate (14) provided on the upper mold (11)
Both sides of the leg portions (20b) of the first movable mold (20) (
20c). Further, gates (16) and (18) provided on the lower mold (12) are also partially closed by the legs (22b) and (22c) of the second movable mold (22). Gate (16) (1) of lower mold (12)
8) is the gate (14) of the upper mold (11) as shown in Figure 2.
) are placed on the left and right of the gates (14) and (16).
(18) are spaced apart from each other. gate (16)
(18) is located below one main surface (2a) of the support plate (2), and the gate (14) is located above one main surface (2a) of the support plate (2).

Above the gates (16) (18) are the first movable molds (
20), the sealing resin (29) injected from the gates (16) and (18)
), the flow toward one main surface (2a) of the support plate (2) is restricted by the lower surfaces of the legs (20b) and (20c). Therefore, from the gates (16) and (18), the sealing resin (2
9) is injected. A sealing resin (29) is injected from the gate (14) through the notch (20a) of the first movable mold (20) onto one main surface (2a) of the support plate (2). A portion of the gate (14) is closed by the legs (20b) and (20c) to narrow the opening. Therefore, the injection of the sealing resin (29) into the one main surface (2a) side of the support plate (2) through the gate (14) is weakened. On the other hand, the sum of the opening areas of the gate (16) and the gate (18) is larger than the opening area of the gate (14) and extends from the gate (16) (18) to the other main surface (2) of the support plate (2).
The injection of the sealing resin (29) into the b) side is relatively strengthened. As a result, one main surface (2) of the support plate (2)
The sealing resin (29) can be injected in a well-balanced manner onto the a) side and the other main surface (2b) side.

After the sealing resin (29) is sufficiently injected into the molding cavity (27) and the support plate (2) is fixed by the sealing resin (29), the first and second movable molds (20 ) (22) is moved away from the support plate (2). The gate (
14) occlusion by the legs (20b) (20c);
Legs (22b) (22c) of gates (16) (18)
) is removed. Also, the cavities formed by the movement of the first and second movable molds (20) and (22) directly communicate with the gates (14) and gates (16) and (18), respectively. Therefore, the gates (14
) and gates (16) (18) to sealing resin (2
9) can be reliably injected. The first movable mold (20) and the second movable mold (22) have an upper surface (22d) and a lower surface (22d).
0d) substantially coincide with the top and bottom surfaces of the molding cavity (27), respectively. In addition, since the sealing resin (29) is injected into the notch (20a) of the first movable mold (20), the completed resin sealing body (31) has this as shown in FIG. A convex portion (32) corresponding to this is formed.

This protrusion (32) may be removed, but the height of the protrusion (32) is the same as that between one main surface (2a) of the support plate (2) and the creeping surface of the molding cavity (27) opposite thereto. Corresponding to the spacing, the thickness is smaller than the thickness of the thick portion of the resin sealing body (31) on the one main surface (2a) side of the support plate (2), so there is no problem even if it is not removed.

This embodiment described above has the following effects.

(1) First and second movable molds (20) (22)
closes part of the gate (14) and gates (16) and (18), and the voids formed after the movement of the first and second movable molds (2o) and (22) close the gate (14) and gates, respectively. (16) leads directly to (18). Therefore, the first
Even if the movement of the second movable molds (20, 22) is delayed, the sealing resin (29) can be reliably injected into the void.

(2) Almost the entire molding cavity (27) is filled with sealing resin (
29), the other end of the support plate (2) is held between the first and second movable molds (2o) (22), so the support plate (2) is tilted during resin molding. This can be reliably prevented, and a thin resin layer having a substantially uniform thickness can be satisfactorily formed on the other main surface (2b) side of the support plate (2).

(3) The sealing resin (29) is not easily injected onto the other main surface (2b) side of the support plate (2).
9) is injected strongly, so one main surface of the support plate (2) (
The sealing resin (29) can be injected into the main surface 2a) and the other main surface (2b) in a well-balanced manner, and the resin sealing body (3) can be formed satisfactorily.

(4) In this embodiment, the lengths of the flow paths (the length of the runner and the gate) of the plurality of sealing resins (29) extending from the same pot are equal.

Therefore, each molding cavity (27) leading to the same pot
A substantially equal amount of the sealing resin (29) can be injected. Therefore, by measuring the moving distance of the plunger (30), it is possible to accurately recognize when the first and second movable molds (20) and (22) move.

(5) The ratio of the sealing resin (29) injected to one main surface (2a) side and the other main surface (2b) side of the support plate (2) is determined by the notch of the first movable mold (20). It can be easily adjusted by changing the width of the portion (20a). Therefore, various manufacturing conditions can be accommodated without major design changes to the expensive molding die (10).

(6) Since the support lead connecting strip (9) is cut and removed before the transfer molding process, this problem occurs when the support lead (8) is cut and removed after molding the resin sealing body (31) as in the conventional case. The resin sealing body (31) is not damaged.

The above-described embodiment of the present invention can be modified in various ways.For example, FIGS. 7 to 11 show other embodiments of the present invention. Components that are the same as those shown in FIGS. 1 to 6 are denoted by the same reference numerals, and explanations thereof will be omitted.

As shown in FIGS. 7 and 8, the first movable mold (20)
A protrusion (lla) is formed on the upper mold (11) to be placed within the cutout (20a). The protrusion (lla) is attached to the support plate (
2) is spaced apart from one principal surface (2a) by a predetermined thickness of the resin sealing body (31). In this state, after filling the molding cavity (27) with a predetermined amount of sealing resin (29), the ninth
As shown in Fig. 10, the second movable mold (2
0) and (22) are moved away from the upper molds (11) and (12), respectively. After the first movable mold (20) is moved, the lower surface (20d) of the first movable mold (20) has a protrusion (
lla) is placed on the same plane as the lower surface of the For this reason, the molded resin sealing body (31) does not have the convex portion (32) shown in FIG. 6, as shown in FIG. 11.

Further modifications are possible in the embodiments of the present invention.0 For example, in this embodiment, the semiconductor chip (4) as an electronic element is directly fixed to the support plate (2), but the electronic element is fixed to the support plate (2). (2) may be indirectly fixed to 6
For example, it is also effective for electronic components in which a circuit board on which electronic elements are mounted or formed is fixed to a support plate.

The width of the first movable mold (20) may be smaller than the width of the support plate (2). However, the first main surface (2) of the support plate (2)
Preferably, the first movable mold (20) extends above the gates (16) and (18) located below a).

The gate (14) may include a portion located below one main surface (2a) of the support plate (2), and the gates (16) and (18) may include a portion located below one main surface (2a) of the support plate (2). Main surface (2
It may include a portion located above a).

The gates (14), (16), and (18) may be formed only on the upper mold (11) or only on the lower mold (12).
11) and the lower mold (12) can be easily realized by providing a step.

The first resin injection port and the second resin injection port may be continuous and form one resin injection port. In this case, the resin injection port doubles as the first resin injection port and the second resin injection port. has a portion located below one main surface of the support plate.

As described above, according to the present invention, a resin-sealed electronic component in which a part of the resin-sealed body is also formed on the other main surface side of the support plate can be provided satisfactorily and easily. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a molding die for transfer molding equipped with a lead frame assembly in the method for manufacturing resin-sealed electronic components according to the present invention, and FIG. 2 is a cross-sectional view taken along line A-A in FIG.
A sectional view taken along the line, FIG. 3 shows the first and second sections in FIG.
A cross-sectional view of the molding mold showing a state in which the movable mold is moved, No. 4
The figure is a sectional view taken along the line B-B of FIG. 3, FIG. 5 is a plan view of a lead frame assembly used in the method of the present invention, and FIG. 6 is a diagram of a resin-sealed semiconductor device obtained by the present invention. A perspective view, FIG. 7 is a sectional view of a mold for transfer molding equipped with a lead frame assembly in another embodiment of the present invention, and FIG. 8 is a sectional view taken along line C-C in FIG. 7. FIG. 9 is a sectional view of the molding die showing the state in which the first and second movable molds have been moved in FIG. 7, and FIG. 10 is a cross-sectional view of the mold shown in FIG.
A sectional view taken along line D and FIG. 11 are perspective views of a resin-sealed semiconductor device obtained according to another embodiment of the present invention. (1), Electronic component assembly, (2), Support plate,
(2a) , , one main surface, (2b) ,
, Other main surface, (3), , External lead, (4
),. Semiconductor chip (electronic element), (10), Molding mold, (14) (1, 6) (18), Gate (resin injection port), (20), First movable mold, (22) ,,
Second movable mold, (27), molding cavity, (2
9), Sealing resin, (31),. Resin sealing body, Fig. 2, Fig. 8

Claims (1)

[Scope of Claims] An electronic component assembly comprising a support plate having an electronic element fixed to one main surface thereof, an external lead connected to one end of the support plate, and a molding cavity formed therein. First and second movable molds are provided so as to be movable toward and away from the molding cavity, and the first movable mold is provided with a notch and one or more openings relative to the molding cavity. and a molding mold provided with a resin injection port, the external lead being held between the molding mold, and the first movable mold being placed in one main mold on the other end side of the support plate. and the second movable mold is brought into contact with the other main surface on the other end side of the support plate, and the main part of the other main surface of the support plate and the molding opposite thereto. The distance between the empty space and the wall is
arranging the electronic component assembly in the mold so that the distance is smaller than the distance between the main part of one main surface of the support plate and the wall surface of the molding cavity opposite thereto; The first movable mold and the second movable mold each close a part of the resin injection port, and the first movable mold injects the resin into the molding cavity on one main surface side of the support plate. The fluidized sealing resin is injected from the resin injection port through the notch onto one main surface side of the support plate of the molding cavity while restricting the flow of the molding cavity from the resin injection port. a step of injecting a fluidized sealing resin onto the other main surface side of the support plate; and after the support plate is substantially fixed by the sealing resin injected into the molding cavity, the first and separating the second movable mold from the support plate, and further injecting the sealing resin into the molding cavity from the resin injection port, and substantially the entire surface of the support plate is covered with the resin sealant. A method of manufacturing a resin-sealed electronic component coated with