JPH0447971B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin sealing method for resin sealing a semiconductor integrated circuit element (hereinafter referred to as IC) mounted on a lead frame.

[Conventional technology]

Usually, a resin sealing device as shown in FIG. 2 is used as a means for resin-sealing an IC mounted on a lead frame. In FIG. 2, an upper mold 1 is fixed to a mold clamping cylinder head 8 and can be moved up and down, and a lower mold 2 is fixed to a table 7. In the center of the lower mold 2, there is a plunger 4 for press-fitting the resin into the cavity 10 between the upper mold 1 and the lower mold 2.
and pot 3 are provided. The plunger 4 is fixed to the cylinder head 5 and the injection cylinder 6
As the plunger 4 moves up and down, the molten resin flows into the runner 1.
2. Pass through the gate 11, press fit into the cavity 10, and seal the IC with resin.

[Problem that the invention seeks to solve]

After the press-fitted resin hardens, the mold clamping cylinder head 8 is raised, and the resin sealing part 10a sealing the IC, the cull 13, and the lead frame 9 are released from the upper mold 1. As the injection cylinder 6 rises further by approximately 2 mm from the position after the resin press-fitting is completed, the lower mold ejector pin 14 provided at the bottom of the resin sealing part 10a rises in conjunction, and the resin sealing part is removed from the lower mold 2. Knock out 10a. Then, the molded lead frame 9, cull 13, and resin sealing part 1
0a is transported to the next process by automatic handling. At this time, since the adhesion force between the cull 13 and the plunger 4 is large, during automatic handling,
It often happens that the cull 13 is separated from the resin sealing part 10a and remains on the mold surface, which not only interferes with automatic operation but also causes the cull 13 to become detached from the resin sealing part 10a.
There was a risk of the mold being sandwiched between the upper mold 1 and the lower mold 2, causing the mold to break.

In addition, after automatically handling the molded lead frame 9, resin burrs generated near the cavities 10, runners 12, and pots 3 of the upper and lower molds 1 and 2, and resin burrs attached to the upper end surface of the plunger 4 are removed. The dust is removed by a dust collection mechanism installed near the mold. At this time, the plunger 4 is cleaned in a knocked-out state, that is, in a state in which the top surface of the head of the plunger 4 is flush with the surface of the lower mold 2 or slightly protrudes from the surface, so that the upper end surface of the plunger 4 can be easily cleaned.
After cleaning, the plunger 4 descends and returns to the position where the next tablet-shaped resin is introduced. Normally, the clearance between the pot 3 and the plunger 4 is 0.01 to 0.02 mm in diameter in order to improve the sliding fit between the pot 3 and the plunger 4.
It is set as. Therefore, when the plunger 4 descends, resin burrs attached around the pot 3 or the head of the plunger 4 may peel off and accumulate on the upper surface of the head of the plunger 4. and,
During the next resin injection, the tablet-shaped resin and the resin burrs accumulated on the top surface of the head of the plunger 4 are injected at the same time, mixed into the cavity 10, and the IC
There were problems such as deforming or cutting the wires connecting the electrodes and external leads, reducing yield and quality.

The present invention provides a method that solves the above problems.

[Means for solving problems]

The present invention is a method of accommodating a semiconductor element mounted on a lead frame in an upper and lower cavity, and sealing the semiconductor element with a resin press-fitted into the cavity from a pot using a plunger. After waiting and opening the upper mold, there is a step of once retracting the plunger to separate it from the cull formed on a part of the hardened resin sealing part, and a step of reciprocating the plunger before cleaning the mold. This semiconductor resin encapsulation method includes the steps of peeling off and removing resin burrs attached to the pot and plunger.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail using the drawings.

An embodiment of the present invention is shown in a to g of FIG.
The following will be explained in order. A shows a state in which a lead frame 9 carrying an IC is held between an upper mold 1 and a lower mold 2, and resin is injected into a cavity 10 by a plunger 4. The cavity 10 is formed by an upper mold 1 and a lower mold 2, and has a runner 1 communicating with the cavity 10.
2 is formed on the upper mold 1. Since the tablet-shaped resin charged into the pot 3 has variations in weight, the cull 13 is set so as to remain in the pot 3 by 1 to 2 mm, taking this variation into account. The top tip of the plunger 4 is cylindrical, and the portion 5 to 10 mm from the top tip has a diameter larger than the inner diameter of the pot 3.
It is made with a clearance of 0.01 to 0.02 mm, and the other parts are made with a diameter 2 to 3 mm smaller than the inner diameter of the pot 3. When the press-fitted resin is completely cured, the upper mold 1 is raised and opened as shown in b.
The upper mold 1 is provided with an upper mold ejector pin 15 for completely releasing the resin sealing part 10a and the cull 13 from the upper mold 1.

Next, as shown in c, after the upper die 1 is raised, the plunger 4 is lowered by about 10 mm to completely separate the plunger 4 from the cull 13.

Next, as shown in d, the plunger 4 is further raised about 2 mm from the injection completion stop position in a, and the plunger 4
3 out of the pot 3, the lower mold ejector pin 14 rises in conjunction with the plunger 4 from about 1 mm above the injection completion stop position of the plunger, and knocks out the resin sealing part 10a. The molded lead frame 9 and cull 13 are then automatically handled and transported to the next process. Next, as shown in e, the plunger 4 is moved up and down several times within a distance of about 10 mm from the top of the pot 3, where resin burrs are likely to occur, to peel off the resin burrs attached to the inner surface of the pot 3 and around the upper end of the plunger 4. In the state where the peeled resin burr is pushed up outside the pot 3 by the plunger 4, that is, in the state f,
A dust collection mechanism installed near the mold removes resin burrs, etc. As shown in the next g, the plunger 4 returns to the position where the resin in the form of a tablet is introduced.

〔Effect of the invention〕

According to the present invention, the plunger is completely separated from the cull before automatic handling, as shown in the process of FIG. Problems can be solved and lead frames and culls can be handled automatically after molding.

In addition, as shown in the step in Figure 1e, by reciprocating the plunger before cleaning,
Resin burrs attached to the inner surface of the pot and around the upper end of the plunger can be peeled off and removed, preventing resin burrs from entering the cavity during the next injection of resin, eliminating concerns about wire deformation and disconnection, and reducing yield. and improvement in quality can be expected.

[Brief explanation of the drawing]

FIG. 1a is a sectional view showing how the upper mold and lower mold are clamped together and resin injection is completed with a plunger in the present invention, and FIG. 1b is a sectional view showing how the upper mold is raised.
c is a cross-sectional view showing the plunger descending and releasing the plunger and cull from the mold; d is a cross-sectional view showing the molded lead frame and cull being knocked out by the plunger and the lower mold ejector pin. , e is a sectional view showing how the plunger is moved up and down to peel off the resin burr, f
is a sectional view showing the working position of the dust collection mechanism (not shown);
g is a cross-sectional view showing the position where tablet resin is introduced, and FIG. 2 is a cross-sectional view showing how resin sealing is performed. 1...upper mold, 2...lower mold, 3...pot, 4...
...Plunger, 5...Cylinder head, 6...
Injection cylinder, 7... table, 8... mold clamping cylinder head, 9... lead frame, 10
a...Resin sealing part, 11...Gate, 12...Runner, 13...Cull, 14...Lower die ejector pin, 15...Upper die ejector pin.

Claims (1)

[Claims] 1 A method in which a semiconductor element mounted on a lead frame is housed in an upper and lower cavity, and the semiconductor element is sealed with resin that is press-fitted into the cavity from a pot with a plunger, and the semiconductor element is sealed by waiting for the press-fitting resin to harden. After opening the upper mold, the plunger is moved back, and the plunger is separated from the cull formed in a part of the hardened resin sealing part.Before cleaning the mold, the plunger is moved back and forth to remove the pot. and a step of peeling off and removing resin burrs attached to the plunger.