JP2011104873A - Mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold the improvement in molding quality of which can be expected by devising the form of a mold runner gate. <P>SOLUTION: An in-cavity runner gate 12 is set in a mold cavity area where a mold cavity 8 molding a plurality of semiconductor elements 10 mounted on a substrate all together is formed. The in-cavity runner gate 12 is formed so that the depth of a groove is made to approach the depth of the mold cavity 8 stepwise from the side of a mold cull 11 toward the opposite edge 8a on the opposite side of the mold cavity 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mold for resin molding a semiconductor device.

In the transfer molding apparatus, a workpiece and a sealing resin (for example, a resin tablet) are supplied to a mold mold that is opened and clamped, and the molten resin loaded in the pot is molded through a mold cull and a mold runner gate. It is pressure-fed to the mold cavity and resin-molded.
Since the mold gate separates unnecessary resin from the molded product after resin molding (gate breaks), the shape of the die gate with a reduced cross-sectional area up to about 60% of the thickness of the molded product (for example, a V-shaped notch is provided). Formed shape).
In addition, there has been proposed a mold die having an equivalent cross-sectional area without providing a notch at a connecting portion between a sealing resin and an unnecessary resin in a molded product after resin molding (see Patent Document 1).

JP 2009-39867 A

  However, when the thickness of the package portion is reduced to, for example, about 0.25 mm, the conventional gate is formed to a depth of about 0.15 mm. The exchange speed is increased, the gel time is shortened, and the viscosity of the resin during the flow increases, which may cause a wire flow of the semiconductor element mounted on the substrate. Even if a mold having a cross-sectional area equivalent to the connecting portion between the sealing resin and the unnecessary resin in Patent Document 1 is used, the above-described problem cannot be overcome if the thickness of the package portion is reduced.

  In addition, microvoids (for example, invisible fine bubbles contained in the resin tablet) are flowing in the molten resin in the mold runner, and when passing through the mold gate with a reduced cross-sectional area, A vortex is generated on the downstream side of the mold gate, and micro voids (fine bubbles) are merged to grow into a visible size void, which is pushed further downstream and is formed by a row of bubbles at the periphery of the molded product. A flow mark is formed.

In the sealing resin, fillers of various diameters are uniformly mixed as a reinforcing material, but the distribution of filler diameters is biased by the vortex generated on the downstream side of the mold gate. For example, when the flow meanders or curves in the mold cavity, a large-diameter filler is deposited on the outside, and a small-diameter filler tends to be volumed on the inside. Further, in a high-speed flow, a large-diameter filler having a large pressure-receiving area of the flowing resin reaches the periphery of the mold cavity, but a small-diameter filler having a small pressure-receiving area tends to be volumed near the entrance of the mold cavity.
As described above, in a product in which a molded product becomes thin and is molded by batch molding, there is a concern that the molding quality may be deteriorated due to the structural factors of the mold described above. It takes time and cost to solve this problem by improving the quality of the sealing resin.

  An object of the present invention is to solve the above-described problems of the prior art and to provide a mold that can be expected to improve molding quality by devising the form of a mold runner gate.

In order to achieve the above object, the present invention comprises the following arrangement.
A mold mold that clamps a workpiece with an upper mold and a lower mold and fills a mold cavity with a mold runner that connects the sealing resin loaded in the pot to the mold cull. An in-cavity runner gate connected to the mold runner is engraved in the mold cavity area in which a mold cavity for collectively molding the semiconductor elements is formed, and the runner gate in the cavity is the mold The groove depth is engraved so as to gradually approach the depth of the mold cavity from the cull side toward the opposite side on the opposite side of the mold cavity.

  The in-cavity runner gate is formed with a stepped portion so that the groove depth decreases stepwise from the mold cull side to the opposite side of the mold cavity opposite to the mold cavity. A sealing resin is filled stepwise from the upstream side of the mold cavity close to the mold cull.

  The groove width of the in-cavity runner gate is formed so as to gradually increase from the mold cull through the mold runner toward the opposite side of the mold cavity.

  The in-cavity runner gate has a tapered surface so that the groove depth gradually decreases from the mold cull toward the middle of the mold cavity, and the mold cavity of the mold cavity is formed along the tapered surface. The sealing resin is filled stepwise from the upstream side close to the mold cull.

  An ejector pin that pushes and releases a molded product according to a mold opening operation is provided so as to protrude from the bottom of the runner gate in the cavity and the mold cavity corresponding to the extension line of the runner gate. And

If the mold is used, an in-cavity runner gate connected to the mold runner is engraved in the mold cavity area where a mold cavity is formed in which a plurality of semiconductor elements mounted on a substrate are molded together. The runner gate in the cavity is engraved so that the groove depth gradually approaches the depth of the mold cavity from the mold cull toward the opposite side of the mold cavity. Therefore, since the groove depth of the runner gate in the cavity is formed to be deeper than the depth of the mold cavity, the cross-sectional area is not reduced when the sealing resin flows into the mold cavity. The exchange speed is increased, the gel time is shortened, the viscosity of the resin during the flow is not increased, and there is no possibility of causing the wire flow of the semiconductor element mounted on the substrate.
In addition, since it does not pass through a mold gate with a reduced cross-sectional area, a vortex is generated on the downstream side of the mold gate, so that micro voids (fine bubbles) are combined and visible. It grows into a void and is pushed further downstream, so that a flow mark due to a row of bubbles is not formed at the periphery of the molded product.
Further, no vortex flow is generated on the downstream side of the mold gate having a reduced cross-sectional area, and there is no bias in the distribution of the filler diameter mixed in the sealing resin.
Therefore, the mold cavity for collectively molding a plurality of semiconductor elements mounted on the substrate can be spread from the upstream side near the mold cull to the downstream side of the peripheral edge of the mold cavity while being sequentially filled with the sealing resin. Therefore, it is possible to improve the molding quality. In particular, in a product in which a molded product becomes thin and is molded by batch molding, improvement in molding quality can be realized by the structural contrivance of the mold.

  A stepped portion is formed so that the groove depth decreases stepwise from the mold cull toward the opposite side of the mold cavity, or the groove depth from the mold cull toward the middle of the mold cavity. When the taper surface is formed so as to gradually become shallower, the sealing resin is gradually filled from the upstream mold cavity close to the mold cull, so that no vortex flow is generated downstream of the gate. Thus, sufficient gel time can be secured and uniform sealing resin can be filled.

  If an ejector pin that pushes and releases a molded product according to the mold opening operation can be projected at the bottom of the runner gate in the cavity and the mold cavity corresponding to the extension line, Although the unnecessary resin existing in the runner gate is formed thicker than the molded product, it can be released without affecting the molded product by hitting the ejector pin against the unnecessary resin.

It is sectional explanatory drawing before and after the start of the resin sealing operation | movement using the mold metal mold | die which concerns on Example 1. FIG. FIG. 2 is a plan view of the upper mold of FIG. 1 and a cross-sectional view of the upper mold as viewed from the end portion of the in-cavity gate runner. It is sectional explanatory drawing before and behind the completion of the resin sealing operation | movement using the mold metal mold | die which concerns on Example 1. FIG. FIG. 4 is a plan view of the upper mold of FIG. 3 and a cross-sectional view of the upper mold as viewed from the end portion of the gate runner in the cavity. It is a plane explanatory view showing the flow of sealing resin from a mold gate runner to a mold cavity. 6 is a cross-sectional view of a mold according to Example 2 and a plan view of an upper mold. FIG.

  Hereinafter, a preferred embodiment of a mold according to the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, description will be made using a transfer molding apparatus using a mold die in which a cavity recess is formed on the upper mold side and a pot is formed on the lower mold side. In the transfer molding apparatus, the lower mold is described as a movable mold and the upper mold is described as a fixed mold.

  First, a schematic configuration of the transfer molding apparatus will be described with reference to FIG. The mold 1 includes an upper mold 2 and a lower mold 3. The mold mold 1 clamps a workpiece with an upper mold 2 and a lower mold 3, and a mold cavity through a mold runner 7 in which a sealing resin (resin tablet) 5 loaded in a pot 4 is connected to a mold cal 6. 8 is filled.

The upper mold 2 is formed with a mold cavity 8 for collectively molding a plurality of rows and columns of semiconductor elements 10 mounted on a substrate 9 as a workpiece. In addition, a mold cull 6 is formed on the upper mold 2 at a position facing the pot 4, and an in-cavity runner gate 12 connected to the mold runner 7 is engraved in the mold cavity area.
The in-cavity runner gate 12 has a groove depth that gradually increases from the mold cull 6 (mold runner 7) side to the opposite side 8 a (peripheral edge) on the opposite side of the mold cavity 8. It is engraved so that it approaches.

Specifically, the in-cavity runner gate 12 is formed with a stepped portion 8b so that the groove depth decreases stepwise from the mold cull 6 toward the opposite side 8a on the opposite side of the mold cavity 8. Yes. For this reason, the sealing resin 5 is filled stepwise from the upstream side of the mold cavity 8 near the mold cull 6 along each stepped portion 8b (see FIG. 2).
In this way, the sealing resin 5 is gradually filled from the upstream side of the mold cavity 8 close to the mold cull 6 so that, for example, the entire cavity is sealed from the gate provided at the end of the mold cavity. Compared with a mold mold filled with resin, it is possible to shorten the moving distance of the sealing resin 5 in the mold cavity 8 to ensure a sufficient gel time. Further, since no vortex is generated on the downstream side of the gate, sufficient gel time can be secured and uniform sealing resin can be filled.

  In FIG. 2, the groove width of the intracavity runner gate 12 is formed so as to gradually widen from the mold cull 6 through the mold runner 7 toward the opposite side 8 a of the mold cavity 8. This is because the groove depth of the in-cavity runner gate 12 becomes shallower toward the opposite side 8a of the mold cavity 8, but the cross-sectional area of the in-cavity runner gate 12 does not rapidly decrease due to the widening of the groove width. It is for doing so.

  The lower mold 3 is provided with a lower mold insert 14 that supports the workpiece adjacent to the center insert 13 provided with the pot 4. The upper surface of the lower mold insert 14 is formed with a step corresponding to the plate thickness of the substrate 9 and the upper surface of the center insert 13 and is assembled to a lower mold base (lower mold tee) (not shown). When the substrate 9 is placed on the lower mold insert 14, the upper surface of the substrate is flush with the upper surface of the center insert 13. When the substrate 9 is placed on the upper surface of the lower mold insert 14 and the lower mold 3 is moved upward to close the mold 1, the substrate 9 is clamped by the upper mold 2 abutting against the outer edge of the substrate (FIG. 1). (See (B)).

  A plunger 15 that moves up and down by a known transfer drive mechanism is provided in the pot 4. The plunger 15 is a multi-plunger in which a plurality of plungers 15 are provided on a support block (not shown) corresponding to the plurality of pots 4. When the plunger 15 is moved upward, the molten sealing resin 5 in the pot 4 is pressure-fed to the mold cavity 8 through the mold cull 6, the mold runner 7, and the in-cavity runner gate 12.

  Here, a resin molding operation using the mold will be described with reference to FIGS. As an example, the thickness of the molded product (the depth of the mold cavity 10) is 0.2 mm from the substrate surface, the height of the mold cul 6 from the mold parting line (substrate surface) is 1.0 mm, and the mold cul 6 The height of the in-cavity runner gate 12 connected to the first stepped portion 8b is 0.5 mm, and the height of the stepped portion 8b at the end of the in-cavity runner gate 12 is 0.30 mm.

  In FIG. 1A, a work (substrate 9) is carried onto the upper surface of the lower mold insert 14, and the lower mold 3 to which the sealing resin 5 (resin tablet) is supplied to the pot 4 is raised, Thus, the substrate 9 is clamped.

  Next, as shown in FIG. 1B, when a transfer drive mechanism (not shown) is operated to raise the plunger 15, the mold cavity 8 through the mold cull 6, the mold runner 7, and the in-cavity runner gate 12 is used. Fill the inside with molten resin. At this time, as shown in FIG. 1B and FIG. 2, the sealing resin 5 is filled stepwise from the upstream mold cavity 8 close to the mold cull 6 along each stepped portion 8b.

  Specifically, as shown by the arrows in FIG. 5, along the in-cavity runner gate 12, filling is performed from the upstream side near the mold cull 6 to the mold cavities 8 on both sides along the first step portion 8 b. Then, after the operation of filling the mold cavities 8 on both sides along the second stepped portion 8b is repeated and finally reaches the fifth stepped portion 8b on the downstream side, the mold cavity 8 The sealing resin 5 is sequentially filled up to the peripheral edge (opposite side 8a) of the mold cavity 8 in the same height range (see FIGS. 3 and 4).

Thus, since the groove depth (0.5 mm to 0.3 mm) of the runner gate 12 in the cavity is formed to be deeper than the depth (0.2 mm) of the mold cavity 8, the sealing resin 5 is used as the mold. Since the cross-sectional area is not reduced when flowing into the cavity 8, the heat exchange speed is increased, the gel time is shortened, and the viscosity of the flowing resin is not increased. The wire flow of the semiconductor element 10 mounted on the substrate There is also no risk of causing.
In addition, since it does not pass through a mold gate with a reduced cross-sectional area, a vortex is generated on the downstream side of the mold gate, so that micro voids (fine bubbles) are combined and visible. It does not grow into a void and is pushed further downstream so that a flow mark due to a row of bubbles is not formed on the periphery of the molded product, and the distribution of the filler diameter mixed in the sealing resin 5 may be biased. Absent. Further, even when a gas such as air or gas is present in the mold cavity 8, the air trap is not generated because the gas is sequentially pushed downstream as the sealing resin 5 is filled.
Therefore, the peripheral portion of the mold cavity 8 is filled with the sealing resin 5 sequentially from the upstream side close to the mold cull 6 into the mold cavity 8 for collectively molding the plurality of semiconductor elements 10 mounted on the substrate. Since it can be spread downstream, the molding quality can be improved. In particular, in a product in which a molded product becomes thin and is molded by batch molding, improvement in molding quality can be realized by structural improvements of the mold 1.

As shown in FIGS. 2 and 4, the mold cavity 8 for batch molding is formed in a mold cavity area (one mold cavity 8) in a mold mold having a large resin mold area. A plurality of in-cavity runner gates 12 may be formed as shown by a broken line as well as a single one. In this case, the sealing resin 5 (resin tablet) of one pot 4 may be branched by the mold runner 7 and pumped to the runner gates 12 in each cavity. Moreover, it is good also as a structure which connects the die runner 7 of the sealing resin 5 (resin tablet) of the some pot 4 to each runner gate 12 in each cavity, and pumps. Thereby, a flat package having a thin molded product and a wide resin mold area (area of the mold cavity) can be resin-molded efficiently and with high quality.
Further, the molded product after the resin molding is removed from the mold 1 by an ejector pin mechanism (not shown) and conveyed to a degate portion not shown. The degate portion is twisted to cause stress concentration at the step portion between the die runner 7 and the cavity runner gate 12 and divided, and the degate line 11 from the step portion to the end of the substrate 9 (see FIG. 3B). The molded product after resin molding is separated from the molded product cal and the molded product runner (unnecessary resin).

Next, another example of the mold 1 will be described with reference to FIG. The same members as those in the first embodiment are denoted by the same reference numerals, and the description will be used.
In the present embodiment, since the configuration of the lower mold 3 in the mold 1 is the same, the description will be used, and the configuration of the upper mold 2 will be mainly described.

  6A, the in-cavity runner gate 12 formed in the upper mold 2 is formed with a tapered surface 12a so that the groove depth gradually decreases from the mold cull 6 toward the middle of the mold cavity 8. In FIG. Has been. In FIG. 6B, the sealing resin 5 is filled stepwise from the upstream side of the mold cavity 8 close to the mold cull 6 along the tapered surface 12a.

  Further, in FIG. 6A, an ejector pin that pushes and releases a molded product in accordance with a mold opening operation on the bottom 12b of the runner gate 12 in the cavity and the mold cavity bottom 8c corresponding to the extension line thereof. 16 is provided to be able to project and retract. The ejector pin 16 that abuts against the mold cavity bottom 8c having a relatively large area is provided with a diameter-expanding member 16a that expands the contact area of the tip in order to prevent cracks and the like in the molded product. Also good.

  As described above, the unnecessary resin existing in the runner gate 12 in the cavity is formed thicker than the molded product, but by releasing the ejector pin 16 against the unnecessary resin, the mold is released without affecting the molded product. Can do. Since the molded product is danced by a cutting device using a dicing blade or a laser after resin molding, unnecessary resin existing in the runner gate 12 in the cavity does not affect the molding quality.

The mold 1 described above has been described using an upper mold cavity and a lower mold pot arrangement type mold mold, but may be a lower mold cavity, or an upper mold pot and a lower mold cavity arrangement mold mold. 1 may be sufficient.
Further, although the fixed mold is described as the upper mold 2 and the movable mold is the lower mold 3, the present invention is not limited to this, and the fixed mold may be the lower mold 3 and the movable mold may be the upper mold 2.

1 Mold Die 2 Upper Die 3 Lower Die 4 Pot 5 Sealing Resin 6 Die Cull 7 Die Runner 8 Die Cavity 8a Opposite Side 8b Stepped Part 8c Die Cavity Bottom 9 Substrate 10 Semiconductor Element 11 Digate Line 12 Runner gate in cavity 12a Tapered surface 12b Bottom 13 Center insert 14 Lower mold insert 15 Plunger 16 Ejector pin 16a Diameter expansion material

Claims (5)

  A mold mold that clamps a workpiece with an upper mold and a lower mold and fills a mold cavity with a mold runner that connects the sealing resin loaded in the pot to the mold cull. An in-cavity runner gate connected to the mold runner is engraved in the mold cavity area in which a mold cavity for collectively molding the semiconductor elements is formed, and the runner gate in the cavity is the mold A mold die, wherein a groove depth is engraved so as to gradually approach the depth of the die cavity from the cull side toward an opposite side opposite to the die cavity.   The in-cavity runner gate is formed with a stepped portion so that the groove depth decreases stepwise from the mold cull side to the opposite side of the mold cavity opposite to the mold cavity. The mold according to claim 1, wherein the mold resin is filled stepwise from the upstream side of the mold cavity close to the mold cull.   The mold die according to claim 1 or 2, wherein a groove width of the runner gate in the cavity is formed so as to gradually widen from the die cull through the die runner toward the opposite side of the die cavity.   The in-cavity runner gate has a tapered surface so that the groove depth gradually decreases from the mold cull toward the middle of the mold cavity, and the mold cavity of the mold cavity is formed along the tapered surface. The mold according to claim 1, wherein the sealing resin is filled stepwise from the upstream side near the mold cull.   2. An ejector pin that pushes and releases a molded product in accordance with a mold opening operation is provided so as to protrude from a bottom of the runner gate in the cavity and a mold cavity corresponding to an extension of the runner gate. 5. The mold die according to any one of items 4 to 4.

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