JP2693834B2 - Mold for package molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding an air vent of a runner of a package molding die by a transfer molding method, a synthetic resin is introduced into a cavity through a runner for the purpose of preventing resin residue in the air vent of the runner. In a mold for injecting into a mold to form a package, an air vent at the end of the runner is provided with a gap portion on the end side that does not cause resin leakage, and the gap increases as it gets closer to the runner. Configure in shape.

[Industrial applications]

The present invention relates to an air vent for a runner of a package molding die by a transfer molding method.

FIG. 6 shows a transfer molding type package molding die 1 with the upper die removed for the right half.

 2 is a lower mold and 3 is an upper mold.

4 is a pot, 5 is a runner extending radially, and 6 is a cavity for molding a package.

 Reference numeral 7 is an air vent at the end of the runner 3.

The air vent 7 is for letting air and gas at the time of resin injection escape to the outside, and it is necessary that there is no clogging at the end stage of each molding operation which is repeatedly and cyclically performed. This is because if clogging occurs, the air will not escape easily and voids will often remain, leaving bubbles in the package.

Further, the air vent 7 needs to be a narrow gap such that the resin does not leak outside. With such a narrow width, the resin that has flowed into the air vent 7 becomes a film and easily adheres to the mold, and when the runner is released from the mold, it is easily broken and partly adheres and remains.

Therefore, the air vent 7 is required to be a narrow passage that allows air to escape but to limit leakage of the resin, and has a structure in which the resin cured in the air vent 7 is easily released from the mold.

[Conventional technology]

FIG. 7 shows the end portion of the runner of the conventional package molding die 10. It is an expanded sectional view which follows the XX line in FIG.

 11 is a lower mold and 12 is an upper mold.

As shown in FIG. 8, the lower mold 11 is provided with a groove 13 forming a runner and an extremely shallow groove 14 having a depth d ₁ of about 50 μm for forming an air vent.

 Reference numeral 15 is a protruding pin, which faces the bottom surface of the groove 13.

When the lower mold 11 and the upper mold 12 are combined, the runner 5 and the air vent 16 having the gap g ₁ of 50 μm are formed as shown in FIG. 7.

The resin is injected into each cavity 6 from the pot 4 in FIG. 6 through the runner 5 to form a package. The air in the runner 5 is released to the outside through the air vent 16.

When the resin reaches the end of the runner 5, as shown in FIG. 9, a part of the resin flows into the air vent 16 so as to soak into the air vent 16, and is cured in the middle to form an overhang portion 18.

Further, a rod portion 19 corresponding to this is formed in the runner 5.

FIG. 10 shows the state at the time of mold release. Similarly to the package, the rod portion 19 is also pushed up by the ejection pin 15 and released from the runner 5.

The package is taken out of the mold, and the upper and lower molds 1 again
1,12 are combined and the package is molded again.

 The above operation is repeated cyclically.

[Problems to be solved by the invention]

The overhanging portion 18 is an extremely thin film having a thickness of 50 μm, and the thickness t ₁ of the connecting portion 17 with the rod 19 is as thin as 50 μm, and the mechanical strength of this portion is weak. Therefore, at the time of mold release, depending on the adhesive force to the lower mold, the reference numeral in FIG.
As shown by 18a, it breaks and remains in the groove 14 of the lower mold 11.

As shown in FIG. 11 in which the overhanging bent portion 18a remains in the groove 14, the air vent 16 is clogged when the upper and lower molds 11 and 12 are combined.

If the air vent 16 is clogged, the air will not escape easily, resulting in frequent void defects in the package.

Looking at the air vent of the cavity 6, there is a lead frame in this portion, and the resin overhanging portion adheres to the lead frame as well, and the resin is more closely attached to the lead frame than to the mold, so the mold release Sometimes it is released from the mold together with the lead frame, and it is unlikely that it will stick to the mold and remain, so there is no problem.

It is an object of the present invention to provide a package molding die capable of preventing resin residue on the air vent of the runner.

[Means for solving the problem]

According to the present invention, in a mold for molding a package by injecting a synthetic resin into a cavity through a runner, an air vent at the end of the runner has a gap portion at the end side that does not cause resin leakage. From this, the shape is such that the clearance increases as it gets closer to the runner.

[Action]

By making the air vent the above shape, the cross-sectional area of the connection portion with the rod portion formed in the runner of the overhang portion that has entered and hardened becomes wider than the conventional one,
The strength of the connecting portion is stronger than that in the conventional case, and it is less likely that the protruding portion will break at the connecting portion when the rod portion is released.

As a result, it becomes difficult for resin to remain in the air vents, the air vents are less likely to be identified, and air void defects in the package are less likely to occur.

〔Example〕

FIG. 1 is a view corresponding to FIG. 7, showing a terminal portion of a runner of a package molding die 20 according to an embodiment of the present invention.

 21 is a lower mold and 22 is an upper mold.

As shown in FIG. 2, the lower mold 21 is provided with a groove 23 forming a runner, a shallow groove 24 forming an air vent, and a protrusion pin 25.

From the outer wall side of the lower mold 21, the groove 24 has a first groove 24 _-1 having a depth d ₂ of 50 μm and a length l ₁ of 10 mm, and a length l ₂ of 10 mm, which is the same as the upper length l _1. , The second groove 24 _-2 having a gradually increasing depth from d ₂ = 50 μm to d ₃ = 200 μm, and a depth d ₄ = 200 μm
At m, the width gradually widens to a width w _{2 that} is twice the width w ₁ of the groove 23, and is a substantially semicircular shape in plan view, and includes a third groove portion 24 _-3 communicating with the groove 23. . The width of the first and second groove portions 24 _-1 , 24 _-2 is the same as that of the groove 23.

When the lower die 21 and the upper die 22 are combined, a runner 5 is formed as shown in FIG. 1, and an air vent 27 is formed at the end of the runner 5 opposite to the resin injection port. It

The air vent 27 has an inlet portion 27 _-1 , an intermediate portion 27 _-2, and an end portion.
It consists of 27 _-3 .

The terminal portion 27 _-3 is a portion formed by the first groove portion 24 _{-1 and} is a cross-sectional view taken along the line III A-III A in FIG. 1. Third
As shown in Figure (A), the width is w ₁ and the gap (height) g ₂ is 50.
μm. 50 μm is narrow enough to limit leakage of resin, and this portion functions similarly to the conventional air vent 16.

Intermediate portion 27 _-2 is a part of the second groove portion 24 _-2 to form the middle is a sectional view taken along in FIG. 1 III B-III B line. As shown in FIG. 3 (B), the width is w ₁ , the gap (height) g ₃ is 100 μm, and the end on the inlet portion 27 ₋₁ side is line III C-III C in FIG. As shown in FIG. 3C, which is a sectional view taken along the line, the width is w ₁ and the gap (height) g ₄ is 200 μm.

The inlet portion 27 _-1 is a portion formed by the third groove portion 24 _{-3 and} has a width as shown in FIG. 3 (D) which is a sectional view taken along the line III D-III D in FIG. 1. With w ₂ , the gap (height) g ₅ is 200
μm.

The air vent 27 has a shape in which the clearance (height) gradually increases as the air vent 27 deviates from the end on the side of the intermediate portion 27 _-2 of the end portion 27 _-3 toward the runner 5.

The intermediate portion 27 _-2 and the inlet portion 27 _-1 have a function of making the resin that flows into this portion and hardened thick to increase the strength of the connecting portion with the rod portion 19 and to make it difficult to break during release.

In addition, the inlet portion 27 _-1 is wide and has a function of enlarging the contact area between the resin and the mold to promote curing of the resin.

 FIG. 4 shows a state during resin injection.

The resin is injected from the pot 4 in FIG. 6 through the runner 5 into each cavity 6 to form a package. The air in the runner 5 is released to the outside through the air vent 27.

When the resin fills the runner 5, the resin enters the air vent 27.

The resin first spreads left and right to fill the inlet portion 27 _-1 , then enters the intermediate portion 27 _-2 , and finally enters the terminal portion 27 _-3 .

First, at the inlet 27 _-1 , the thickness t ₂ is 200 μm, which is about 4
Although it is twice as thick, it spreads to the left and right to increase the contact area with the mold, so the resin cures relatively quickly.

The resin gradually becomes thinner as it enters the middle portion 27 _-2 , and the curing further proceeds.

When the tip of the resin reaches the end of the middle part 27 _-2 ,
That is, the end portion 27 _-3 is hardened without entering into the end portion 27 _-3 .

FIG. 5 shows a state in which the rod portion 19 formed in the runner 5 is pushed up by the push-out pin 25 and released from the mold.

Along with the rod portion 19, the protruding portion 30 that has entered and hardened in the air vent 27 is also released from the groove 24.

Here, in the overhanging portion 30, the thickness t ₁ of the connecting portion 31 with the rod portion 19 is 200 μm, which is four times that of the conventional _one , and the strength of the connecting portion 31 with the rod portion 19 is several times that of the conventional one.

As a result, when the rod portion 19 is released from the mold, the overhanging portion 30 is released from the groove 24 (lower mold 21) without being broken at the connection portion 31, and no resin residue remains in the groove 24.

Therefore, when the molded package is taken out of the mold and the upper and lower molds 21 and 22 are combined, the result is as shown in FIG. 1, and the air vent 27 is not clogged. In this way, the air vent 27 is not clogged, and the occurrence of void defects in the package is satisfactorily avoided.

〔The invention's effect〕

As described above, according to the present invention, the overhang portion that enters the air vent from the runner and overhangs and hardens, and the strength of the connection portion with the lot portion formed in the runner becomes stronger than the conventional one, and It is possible to effectively prevent breakage during molding. As a result, it is possible to prevent the resin from remaining in the air vents, and to prevent frequent occurrence of void defects in the package due to clogging of the air vents of the runner in the transfer molding method in which molding is performed one after another.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mold for molding a package according to an embodiment of the present invention, FIG. 2 is a diagram showing a lower mold in FIG. 1, FIG. 3 is a diagram showing a shape of an air vent, and FIG. Is a diagram showing a state at the time of resin injection, FIG. 5 is a diagram showing a state at the time of mold release, FIG. 6 is a diagram showing a general package molding die, and FIG. 7 is a conventional package molding die. Fig. 8, Fig. 8 is a diagram showing a lower mold in Fig. 7, Fig. 9 is a diagram showing a state at the time of resin injection, Fig. 10 is a diagram showing a state at the time of mold release, and Fig. 11 is an air vent. It is a figure which shows a clogged state. In the figure, 5 is a runner, 20 is a package molding die, 21 is a lower die, 22 is an upper die, 23 is a groove, 24 is a shallow groove, 24 _-1 is a first groove portion, 24 _-2 is a first groove portion. 2 groove portion, 24 _-3 is a third groove portion, 25 is a protruding pin, 27 is an air vent, 27 _-1 is an inlet portion, 27 _-2 is an intermediate portion, 27 _-3 is an end portion, 30 is a protruding portion, 31 is Shows connections.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-3613 (JP, A) Actually developed S56-154046 (JP, U)

Claims (1)

(57) [Claims] 1. A mold for molding a package by injecting a synthetic resin into a cavity through a runner, wherein an air vent (27) at the end of the runner (5) is provided so that resin leakage does not occur at the end side. The mold for package molding is characterized in that it has a gap (g ₂ ) part (27 _-3 ) and the gap increases as it gets closer to the runner.