JP2001150477A - Molding die for molding lead frame assembly resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the gate breaking of a sealing resin formed by a molding die for molding a lead frame assembly resin by holding a resin-sealed body, a runner resin, and a gate resin only by the first die or the second die when the molding die is opened. SOLUTION: A semiconductor element 7 and a support plate 6 are resin-sealed by holding a lead frame assembly 1 provided with the molding die 2 having the first and second dies 3, 4 for forming a cavity 5 and the support plate 6 to which the semiconductor element 7 adheres between the first and second dies 3, 4 and injecting a fluidized resin into the cavity 5 through a runner 13 formed on the main surface of the second mold 4 and a gate 14 connected to the runner 13. A groove part 11 is formed on the main surface of the first mold 3 to face the runner 13, the resin is packed in the groove part 11 when the fluidized resin is injected into the cavity 5, and the runner resin 13a in the runner 13 is fitted separably from the runner 13 to the groove part 11 when the molding die 2 is released.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame assembly resin mold for preventing resin from adhering to the mold and improving the productivity of semiconductor devices.

[0002]

2. Description of the Related Art A resin-encapsulated semiconductor device includes a support plate and a semiconductor element (semiconductor chip), and the support plate and the semiconductor element are formed by a well-known transfer molding method. Sealed. FIG. 9 shows a transfer mold (22) for forming a resin-sealed semiconductor device. The transfer mold (22) includes a lower mold (23) and an upper mold (24) for forming a cavity (molding space) (5).
And runners (1) formed on the main surface of the upper mold (24) along the plurality of cavities (5) and transporting the fluidized resin.
3), a gate (14) for connecting the runner (13) and the cavity (5) to inject the resin into the cavity (5), and a driving device (20) for moving the upper mold (24). When forming a resin-encapsulated semiconductor device by the transfer molding method, first,
A lead frame assembly (semiconductor device assembly) (1) is formed. In the lead frame assembly (1), the semiconductor element (7) is fixed on the support plate (6), and the semiconductor element (7) and the lead terminal (10)
Are electrically connected by a thin lead wire (8).
As shown in FIGS. 9 and 10, the lead frame assembly (1) is arranged on the lower mold (23) of the transfer mold (22), and the upper mold (24) is moved by the driving device (20). When the transfer mold (22) is closed, a cavity (5) is formed between the lower mold (23) and the upper mold (24) to match the outer shape of the resin sealing body to be formed. Next, the runner is inserted into the cavity (5).
The resin is injected through (13) and the gate (14). The fluidized thermosetting resin injected into the cavity (5) is subjected to a heat treatment at a predetermined temperature for a predetermined time to be cured, and as shown in FIG. 9, the resin sealing body is sealed in the cavity (5). Form. Thereafter, the upper mold (24) is released from the lower mold (23), the lead frame assembly (1) on which the resin sealing body is formed is removed from the transfer mold (22), and the lead frame assembly is removed.
(1) is transferred to a post-process such as a solder dip.

[0003]

A runner (13) and a gate
(14) Runner resin (13a) and gate resin (14a) cured in
Is a sealing resin (5a) for sealing the lead frame assembly (1)
However, since it is unnecessary and easy to remove from the product, it is cut and removed after removing the resin sealing body from the transfer mold (22). However,
From FIG. 9, the runner resin (13a) and the gate resin (14a) have a larger contact area with the upper mold (24) than the lower mold (23).
(13) and the inside of the gate (14), it may not be peeled off integrally with the sealing resin (5a) which easily peels off from the upper mold (23). As a result, a chipped portion of the gate where the connection portion between the gate resin (14a) and the sealing resin (5a) is torn is generated, which causes poor appearance. In addition, the runner resin (13a) and the gate resin (14a) adhered to the upper mold (23) cannot be easily removed by cleaning, and a physical forcible removal step is required, which reduces productivity. Invite you. Therefore, the present invention provides a resin sealing body for only one of the first and second molds when the mold is opened,
It is an object of the present invention to provide a lead frame assembly resin mold capable of holding a runner resin and a gate resin and preventing chipping of a sealing resin from a gate.

[0004]

According to the present invention, there is provided a resin mold for a lead frame assembly according to the present invention, comprising a mold having a first mold and a second mold for forming a cavity. A lead frame assembly (1) having a support plate (6) to which a semiconductor element (7) is fixed is sandwiched between first and second molds (3, 4), and a second mold (4 The fluidized resin is injected into the cavity (5) through the runner (13) formed on the main surface of the () and the gate (14) connected to the runner (13), and the semiconductor element (7) and the support are supported. The plate (6) is sealed with resin. When the fluidized resin is injected into the cavity (5), the resin is filled into the groove (11) formed on the main surface of the first mold (3) facing the runner (13) and molded. When the mold (2) is released, the runner resin (13a) in the runner (13) is locked in the groove (11) so as to be separable from the runner (13). By the groove (11) formed on the main surface of the first mold (3) facing the runner (13), in particular, the wall surface (11a) of the groove (11) perpendicular to the bottom surface of the runner (13), The contact area and frictional force of the runner resin (13a) with respect to the first mold (3) are increased, and the adhesion of the runner resin (13a) to the first mold (3) can be appropriately improved.

A lead frame assembly (1) is sandwiched between the first and second molds (3, 4), and the fluidized resin is passed through a runner (13) and a gate (14) into a cavity (5). When injected and cured, the resin sealing body that seals the support plate (6)
Formed in (5). The runner resin (13a) in the runner (13) is locked in the groove (11), and the runner resin (13a) is held by the first mold (3) when the mold (2) is released. , Runner resin (1
3a), the gate resin (14a) formed in the gate (14) and the sealing resin (5a) formed in the cavity (5) are the first mold (3).
And completely separated from the second mold (4). Thereafter, when the lead frame assembly (1) is removed from the first mold (3), the runner resin (13a) is easily detached from the groove (11),
The runner resin (13a), the gate resin (14a) and the sealing resin (5a) can be integrally removed from the first mold (3).

In an embodiment of the present invention, a plurality of ejector pins (15) for projecting into the runner (13) to press the runner resin (13a) against the first mold (3) are provided, and a plurality of cavities are provided.
The plurality of grooves (11) formed parallel to the runner (13) formed along (5) are arranged between the adjacent ejector pins (15). The depth of the groove (11) may be formed to be 0.3 to 30 mm, and the length of the bottom of the groove (11) may be larger than the length of the inlet.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a resin mold for a lead frame assembly according to the present invention will be described below with reference to FIGS.

A transfer mold (2), which is a molding die according to the present invention shown in FIG. 1, comprises a molding die (2) having first and second dies (3, 4) forming a cavity (5). , A runner (13) formed on the main surface of the second mold (4), and a gate (14) connected to the runner (13). Fixed lower mold (3)
Forms the first mold, and the upper mold (4), which is moved by the driving device (20), forms the second mold. As shown in FIG. 2, the runner (13) is moved along the plurality of cavities (5) into the upper mold.
The fluidized resin formed on the main surface of (4) is transported. The gate (14) connects the runner (13) and the cavity (5), injects fluidized resin into the cavity (5), and supports the semiconductor element (7) disposed in the cavity (5) and the support. The plate (6) is sealed with resin.

In the present invention, the lower mold is opposed to the runner (13).
A groove (11) is formed in the main surface of (3). When the groove (11) is formed, the resin is filled in the groove (11) during resin sealing, and the runner (1) is released when the transfer mold (2) is released.
The groove (1) allows the runner resin (13a) in the 3) to be separated from the upper mold (4).
Lock in 1). Since the runner (13) is formed on the upper mold (4), the runner resin (13a) originally tends to be held by the upper mold (4) having a larger contact area than the lower mold (3) when releasing the mold. According to the present invention, the holding force of the lower mold (3) on the runner resin (13a) can be made larger than that of the upper mold (4) by the grooves (11) formed in the lower mold (3). Therefore, the runner resin (13a), the gate resin (14a) and the sealing resin (5a) can be completely removed from the upper mold (4). The depth of the groove (11) is 0.3 to 30 mm. Groove (1
If the depth of (1) is less than 0.3 mm, the contact area between the runner resin (13a) and the lower mold (3) is small, and the runner resin (13a) is not reliably held by the lower mold (3). If the depth of the groove (11) exceeds 30 mm, the frictional force between the runner resin (13a) and the wall surface (11a) of the groove (11) increases too much, and the runner resin (13a) and the gate resin (14
a) and the sealing resin (5a) become difficult to remove from the lower mold (3) after releasing.

A plurality of ejector pins (1) projecting into the runner (13) to press the runner resin (13a) against the lower mold (3).
5). When the ejector pin (15) is released from the mold, the tip (15a) of the ejector pin is driven by the ejector pin driving device (30).
(13) to project into the runner resin (13a) and the runner resin (13
The gate resin (14a) integrated in a) is peeled off from the upper mold (4). Except at the time of release, the tip (15a) does not protrude into the runner (13) and maintains the state of being housed in the upper mold (4). A plurality of grooves (11) formed parallel to the runner (13) formed along the plurality of cavities (5), as shown in FIG. Ejector pins (1
5) placed between. The ejector pins (15) completely separate the runner resin (13a) and the gate resin (14a) between the grooves (11) that are not sufficiently held in the lower mold (3) from the upper mold (4).

When manufacturing a resin-encapsulated semiconductor device using a transfer mold (2), first, a lead frame assembly (1) shown in FIG. 3 is prepared, and as shown in FIG. It is placed on the lower mold (3) of the transfer mold (2). In the lead frame assembly (1), the semiconductor element (7) is fixed on the support plate (6), and the lead terminal (10) and the semiconductor element (7) are interconnected by the lead terminal connecting strip (10a). Are electrically connected by the thin lead wires (8). On the opposite side of the support plate (6) from the lead terminals (10), the guide lead (9) for positioning the lead frame assembly (1) in the cavity (5) and the guide lead (9) are mutually connected. Guide lead connecting line to be connected (9a)
However, it is also possible to adopt a structure without these.

After placing the lead frame assembly (1) on the lower mold (3), the upper mold (4) is moved downward by the driving device (20) to close the transfer mold (2). As shown in FIG. 1, a cavity (5) accommodating the support plate (6) of the lead frame assembly (1) is formed. Main surface (6a) of support plate (6)
Are formed substantially parallel to the main surface of the lower mold (3).

Next, resin is injected into the cavity (5) through the runner (13) and the gate (14). A thermosetting resin is charged into a pot (molding resin charging hole) (not shown) connected to the runner (13), and is fluidized by pressing with a plunger (not shown). As shown in FIG. 6, the fluidized resin fills the cavity (5) to cover the support plate (6) and the semiconductor element (7), as well as the runner (13), the gate (14), and the groove ( 11)
And cured by heating the transfer mold (2) to a predetermined temperature. The runner resin (13a) in the runner (13) is formed by the groove (11) formed on the main surface of the lower mold (3).
Is hardened integrally with the resin in the groove (11),
(6) and the sealing resin (5a) covering the semiconductor element (7) and the gate resin (14a) are integrally cured.

Thereafter, as shown in FIG. 7, the driving device (20)
The upper die (4) is moved upward by the lower die (3) and the upper die (4).
And mold release. At this time, the runner resin (13a) integrated with the resin in the groove (11) increases the adhesion force and frictional force to the wall surface (11a) of the groove (11), so that the runner resin (13a) is surely engaged with the groove (11). Stop. Also, when releasing, the runner resin (13a) between the grooves (11) is difficult to peel off from the upper mold (4), so the tip (15a) of the ejector pin (15) projects into the runner (13). Then, the runner resin (13a) is pressed against the main surface of the lower mold (3). Therefore, as shown in FIG. 7 and FIG. 8 which is a cross-sectional view taken along the line BB of FIG.
The runner resin (13a) and the gate resin (14a) are completely held in the lower mold (3) without being in close contact with the upper mold (3).

The runner resin (13a) held in the lower mold (3) is
It is removed from the groove (11) by the tensile force, and is taken out from the lower mold (3) together with the gate resin (14a) and the sealing resin (5a). Thereafter, a resin-sealed semiconductor device is formed through a post-process such as cutting off the runner resin (13a) and the gate resin (14a) from the resin-sealed body.

The above embodiment of the present invention can be modified. In the above embodiment, the groove (11) formed in a quadrangle as shown in FIG. 4 is shown, but the groove (11) may be formed in another polygon or a circle. Further, in the above embodiment, the wall surface (11a) of the groove (11) is formed vertically as shown in FIG. 5, but the wall surface (11a) is inclined or provided with a step to extend the bottom of the groove (11). The length may be greater than the length of the inlet. In each case, the same operation and effect as those of the above embodiment can be obtained.

In this embodiment, the following operation and effect can be obtained. [1] The productivity is improved because the runner resin (13a) is securely held in the lower mold (3) and there is no need to remove the runner resin (13a) and the gate resin (14a) from the upper mold (4). be able to. [2] The chipping of the gate of the sealing resin (5a) can be prevented, the appearance defect of the resin-encapsulated semiconductor device can be avoided, and the decrease in yield can be suppressed. [3] The runner resin (13a) engaged with the groove (11) can be easily removed from the lower mold (3). [4] The runner resin (13) for the lower mold (3) is changed by changing the size or shape of the groove (11) and the size of the wall surface (11a).
a) The contact area and frictional force can be adjusted. [5] If the groove (11) is formed, the conventional mold can be directly used in the practice of the present invention.

[0018]

As described above, according to the present invention, the productivity of a resin-encapsulated semiconductor device can be improved and a highly reliable resin-encapsulated semiconductor device can be produced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a molding die for resin molding of a lead frame assembly according to the present invention.

FIG. 2 is a plan view showing a second mold.

FIG. 3 is a plan view showing a lead frame assembly.

FIG. 4 is a plan view showing a state where the lead frame assembly is arranged on the first mold.

FIG. 5 is a sectional view taken along the line AA in FIG. 1;

FIG. 6 is a cross-sectional view showing a state where a molding die is filled with resin.

FIG. 7 is a sectional view showing a state in which a mold is released.

FIG. 8 is a sectional view taken along the line BB of FIG. 7;

FIG. 9 is a cross-sectional view of a conventional mold for resin molding of a lead frame assembly.

FIG. 10 is a plan view showing a state in which a lead frame assembly is arranged on a first mold of a conventional molding die.

[Explanation of symbols]

(1) Lead frame assembly, (2) Mold (transfer mold), (3) First mold (lower mold), (4) Second mold (upper mold) ), (5) · · · cavity, (5a) · · · sealing resin, (6) · · · support plate, (6a) ·
・ Main surface, (7) ・ ・ Semiconductor element, (8) ・ ・ Thin wire,
(9) Guide lead, (9a) Guide lead connecting strip, (10) Lead terminal, (10a) Lead terminal connecting strip (11) Groove, (11a) Wall surface, 13) · runner, (13a) · · runner resin, (14) · gate,
(14a) ・ ・ Gate resin, (15) ・ ・ Ejector pin,
(15a) ・ ・ Tip, (20) ・ ・ Drive device, (30) ・ ・ Ejector pin drive device,

Claims (4)

[Claims] 1. A lead frame assembly having a mold having first and second molds for forming a cavity and having a support plate to which a semiconductor element is fixed is sandwiched between the first and second molds. Then, a fluidized resin is injected into the cavity through a runner formed on the main surface of the second mold and a gate connected to the runner, and the semiconductor element and the support plate are resin-sealed. In a molding die for a lead frame assembly resin mold, when a fluidized resin is injected into the cavity, the resin is filled in a groove formed in a main surface of the first mold facing the runner. A mold for resin molding a lead frame assembly, wherein the runner resin in the runner is locked in the groove so as to be separable from the runner when the mold is released. 2. A plurality of ejector pins protruding into the runner and pressing the runner resin against a first mold, wherein a plurality of ejector pins are formed parallel to the runner formed along a plurality of cavities. The mold according to claim 1, wherein the groove is disposed between the adjacent ejector pins. 3. The molding die according to claim 1, wherein the depth of the groove is 0.3 to 30 mm. 4. The mold for resin molding of a lead frame assembly according to claim 1, wherein the length of the bottom of the groove is longer than the length of the inlet.