JP2007301777A - Mold for forming resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold which is free from the occurrence of the impression or scratch caused by the friction of a lead frame with the mold and also from the occurrence of resin burr in a semiconductor device caused by the impression or the scratch. <P>SOLUTION: When the lead frame 10 is inserted in and set to a cavity block 20, a product lead part 12 and a positioning lead part 13 are respectively received in and held to groove parts 21 and 23 respectively different in shape to position the lead frame in an X-direction and a Y-direction with respect to the groove parts 21 and 23 to stabilize positional precision. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin molding die and relates to a technique for insert molding a resin package on a lead frame used in a semiconductor device.

  Conventionally, semiconductor devices including semiconductor elements, such as diodes, transistors, integrated circuits, and light-emitting diodes, are mounted with a semiconductor element on a lead frame made of a metal plate, and the semiconductor elements are encapsulated by resin molding using a resin molding die. is doing. The resin molding by the resin molding die is performed on the whole or a part of the lead frame on which a plurality of semiconductor elements are mounted.

  More specifically, in the resin molding step, a lead frame having a plurality of lead portions is first placed on the lower mold of the resin mold, and then the upper mold is stacked on the lower mold and clamped. Next, a thermoplastic or thermosetting synthetic resin is injected, the resin is filled in the mold, the mold is opened, and the lead frame is taken out.

  In conventional resin molding dies, the lead frame inserted into the resin molding dies is prevented from shifting from a fixed position due to the resin injection pressure at the time of resin injection, thereby preventing the occurrence of resin burrs. There is. There exists a thing described in patent document 1, for example.

  5 to 7 show a conventional resin mold described in Patent Document 1. FIG. 5 to 7, the resin molding die includes a lower mold 44 and an upper mold 48 that perform resin molding on the lead frame 40. Each of the lower die 44 and the upper die 48 is of a block build type in which a cavity block 41 is sandwiched and a connector block 42 and a tie bar block 43 are combined on both sides thereof.

  The tie bar block of the lower mold 44 is divided into a fixed block 45 and a movable frame pressing block 46 disposed outside the fixed block 45, and the frame pressing block 46 is applied to the outer peripheral end surface of the lead frame 40.

  Further, the frame presser block 46 is provided with a return spring 47 that urges the block to the retracted position, and a cam portion 46a that abuts and follows the cam portion 43a provided on the tie bar block 43 of the upper die 48.

  In the resin molding method according to this configuration, as shown in FIG. 5, first, the resin molding die is opened, and the lead frame 40 is set on the lower mold 44. When the lead frame 40 is set, the frame holding block 46 is urged by the return spring 47 and retracted to the retracted position, so that there is a slight deviation in its positioning as shown in FIG. Even in this case, interference between the lead frame 40 and the tie bar block 43 and interference between the lead frame 40 and the cavity block 41 can be avoided as indicated by a dashed box C in the drawing.

  Next, when the lower die 44 and the upper die 48 are clamped, the cam portion 46a formed on the frame holding block 46 of the tie bar block 43 of the lower die 44 is replaced with the cam portion 43a formed on the tie bar block 43 of the upper die 48. Abut.

  As shown in FIG. 7 (b), the frame pressing block 46 is pushed out toward the fixed block 45 against the return spring 47 by the contact between the cam portion 46a and the cam portion 43a. The lead frame 40 is pushed out.

  Then, the lead frame 40 is held at a predetermined position by the frame pressing block 46 so that the predetermined portion of the lead frame 40 corresponds to the groove 50 of the cavity block 41, and the lead frame 40 is prevented from being displaced due to the resin injection pressure. .

Next, molten resin is injected into the cavity block 41 in this state, and the semiconductor element of the lead frame 40 is resin-sealed to form a resin package.
Another prior art is described in Patent Document 2.
JP 2004-103823 A JP-A-9-76300

  However, even if the lead frame 40 is placed on the lower mold 44 and the tie bar block 43 having the cam mechanism is used to secure the positional accuracy of the lead frame 40 in the above-described conventional configuration, the cavity block 41 and the lead frame Since the relative alignment with the 40 lead portions 40a (leads of the completed semiconductor device) is performed with reference to the pilot hole 51, the lead portion 40a is accurately inserted and set in the groove portion 50 of the cavity 41 itself. Is very difficult.

  Further, the cavity groove 42a formed in the lead block 40a and the connector block 42 forming one side wall of the cavity 41 is formed and processed in a state in which the gap between the lead width and the groove width is eliminated as much as possible. When the lead part 40a is inserted and set in the groove part 42a, the lead part 40a and the cavity groove part 42a rub against each other to generate indentations and scratches, and there is a problem that a resin burr is generated therefrom.

  Also, when the lead portion 40a is inserted into the cavity groove portion 42a and set, and the position accuracy of the lead frame 40 is secured by the tie bar block 43 provided with the cam mechanism, it can be used against the pressing force by the frame pressing block 46. Since the thickness of the lead frame 40 is limited, the lead frame itself may be deformed with respect to a thin lead frame or a lead frame for a small semiconductor device. Furthermore, a resin molding die formed of a plurality of blocks provided with a cam mechanism has a problem that maintenance is very complicated.

  The present invention solves the conventional problems, and does not generate indentations or scratches caused by rubbing between the lead frame and the resin molding die, and resin burrs are caused in the semiconductor device due to the indentations or scratches. An object of the present invention is to provide a resin molding die that does not occur.

  In order to solve the above-mentioned problems, a resin molding die according to the present invention is a resin molding die in which a lead frame is disposed on a lower die, and the upper die is clamped to the lower die and resin molding is performed on the lead frame. In the mold, the lower mold receives and holds the product lead formed on the lead frame, and the positioning lead formed on the lead frame is received and held at a predetermined position of the lower mold. It has a lead holding part for use.

  The product lead holding portion and the positioning lead holding portion each have a groove portion for receiving the lead portion, and a protrusion portion disposed on both sides of the groove portion, and the protrusion portion of the positioning lead holding portion is the product. It is characterized by being set higher than the protruding portion of the lead holding portion for use.

  The product lead holding portion and the positioning lead holding portion each receive and hold the lead portion on a lead receiving surface between opposing guide surfaces, and the positioning lead holding portion includes a guide surface and the positioning lead. A positioning gap is provided between the guide lead and the product lead in the product lead holding portion, and the positioning gap is set narrower than the interference prevention gap. And

  The product lead holding portion and the positioning lead holding portion receive and hold the lead portions on the lead receiving surfaces between the opposing guide surfaces, respectively, and the lead receiving surface width and the positioning for the positioning lead holding portions. A difference value between the lead width and the lead width of the lead is set to be smaller than a difference value between the lead receiving surface width of the product lead holding portion and the lead width of the product lead.

  Further, the angle formed between the guide surface and the lead receiving surface in the positioning lead portion holding portion is set to be narrower than the angle formed between the guide surface and the lead receiving surface in the product lead holding portion. To do.

  As described above, according to the resin molding die of the present invention, when the lead frame is placed on the lower die in the resin molding step, the positioning lead holding portion places the positioning lead portion on the lower die. The product lead holding part that accepts and holds the product lead part by holding in position does not require a configuration for positioning the product lead part, and the product lead part is highly accurate with respect to the cavity. Can be positioned.

  In addition, since the product lead holding part does not require a configuration for positioning the product lead part, the product lead holding part can have a structure with a margin with respect to the product lead part. The product lead portion can be received and held without causing friction due to contact.

  Therefore, the positioning lead holding part accepts and holds the positioning lead part at a predetermined position of the lower mold, so that the lead frame can be prevented from shifting due to the resin injection pressure, and the positioning lead holding part is positioned in the worst case. Even if the lead part is rubbed, the product lead holding part does not rub against the product lead part. As a result, the product lead part is not rubbed or has a resin burr caused by a scratch. It does not occur and high-precision resin molding becomes possible.

  Further, when manufacturing a resin molding die, it is not necessary to prepare a plurality of blocks and further a block provided with a cam mechanism as in the prior art, so that the maintainability is improved and the cost can be reduced.

  Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1A, the lead frame 10 has a pilot hole 11, a product lead part 12, a positioning lead part 13, and a positioning hole 14.

  1B is a top view of the cavity block 20, FIG. 1C is a sectional view taken along line XX ′ of FIG. 1B, and FIG. 2A is an enlarged view of A ′ of FIG. 1B. FIG. 2 and FIG. 2B are enlarged views of B ′ in FIG.

  In FIG. 1B and FIG. 1C, the cavity block 20 is provided in the lower mold of the resin molding die, and the resin molding die is set by inserting the lead frame 10 onto the lower mold. The upper mold is clamped to the mold and the lead frame 10 is resin-molded.

  The cavity block 20 forming a part of the lower mold is formed with a guide block 20b and a cavity convex portion 15 on a main surface 20a. The guide block 20b extends the lead frame 10 and the cavity block 20 in the longitudinal direction (in the drawing). (X direction along XX ′), and the cavity convex portion 15 positions the lead frame 10 and the cavity block 20 in the short direction (Y direction orthogonal to the X direction).

  The guide block 20 b has a product lead holding portion 28 for receiving and holding the product lead portion 12 formed on the lead frame 10 and a positioning lead portion 13 formed on the lead frame 10 on the main surface 20 a of the cavity block 20. A positioning lead holding portion 29 for receiving and holding is formed, and the positioning lead holding portion 29 receives and holds the positioning lead portion 13 so that the lead frame 10 is positioned at a predetermined position of the lower die.

  The product lead holding portion 28 includes a groove portion 21 for receiving the product lead portion 12 and guide protrusion portions 22 disposed on both sides of the groove portion 21, and guide surfaces 22 a formed on both guide protrusion portions 22 face each other. A lead receiving surface forming the bottom surface of the groove portion 21 is formed between the guide surfaces 22a.

  The positioning lead holding portion 29 includes a groove portion 23 that receives the positioning lead portion 13 and guide protrusion portions 24 disposed on both sides of the groove portion 23, and guide surfaces 24 a formed on the guide protrusion portions 24 are opposed to each other. A lead receiving surface that forms the bottom surface of the groove 23 is formed between the guide surfaces 24a.

The height t of the guide protrusion 24 of the positioning lead holding portion 29 is set to be higher than the height t1 of the guide protrusion 22 of the product lead holding portion 28.
As shown in FIG. 2B, the difference value β between the bottom width (W + β) of the groove 23 forming the lead receiving surface in the positioning lead holding portion 29 and the lead width W of the positioning lead 13 is the product lead holding. In the portion 28, the difference is set to be smaller than the difference value α between the bottom surface width (W + α) of the groove portion 21 forming the lead receiving surface and the lead width W of the product lead portion 12.

In other words, the difference value α in the product lead holding portion 28 is set wider than the difference value β in the positioning lead holding portion 29.
In addition, the angle θ formed between the guide surface 24a and the bottom surface of the groove portion 23 that forms the lead receiving surface in the positioning lead portion holding portion 29 is the bottom surface of the groove portion 21 that forms the guide surface 22a and the lead receiving surface in the product lead holding portion 28. The angle is set to be narrower than the angle θ1 formed by

  Therefore, as shown in FIG. 3, on the interface (parting line) 26 between the upper die and the lower die, the distance (W + E) between the guide surfaces 24a of the positioning lead holding portion 29 is the product lead holding portion. It becomes narrower than (W + E1) between the 28 guide surfaces 22a.

  That is, in the positioning lead holding part 29, the gap (1/2) E between the guide surface 24a and the positioning lead 13 forms a positioning gap, and in the product lead holding part 28, the guide surface 22a and the product lead part 12 The gap (1/2) E1 is an interference prevention gap, and the positioning gap is set narrower than the interference prevention gap.

  Hereinafter, the operation of the above-described configuration will be described. FIG. 4 is a state diagram showing a process flow when the lead frame 10 is inserted and set in the cavity block 20 of the resin molding die in the injection molding process forming the resin molding process.

  First, as shown in FIGS. 4 (a) and 4 (b), the pilot pin 31 is inserted into the pilot hole 11 provided in the lead frame 10, and the pilot hole 11 is guided by the pilot pin 31. Going down.

  Next, as shown in FIG. 4C, the height t of the guide projection 24 of the positioning lead holding portion 29 is set higher than the height t1 of the guide projection 22 of the product lead holding portion 28. Therefore, before the product lead portion 12 contacts the guide projection portion 22, the positioning lead portion 13 contacts the guide projection portion 24, and the guide mechanism of the positioning lead holding portion 29 functions first.

  Further, the inclination angle θ of the guide surface 24a of the guide protrusion 24 of the positioning lead holding portion 29 is narrower than the inclination angle θ1 of the guide surface 22a of the guide protrusion 22 of the product lead holding portion 28. In the positioning lead holding portion 29, a positioning gap forming a gap (1/2) E between the guide surface 24a and the positioning lead portion 13 is formed in the product lead holding portion 28. It is narrower than the interference preventing gap forming the gap (1/2) E1.

  Therefore, when the lead frame 10 descends toward the cavity block 20, even if the positioning lead portion 13 that does not contribute to the product shape contacts the guide surface 24 a of the guide protrusion 24, the product lead portion 12 is guided. There is no contact with the protrusion 22. That is, while the positioning lead 13 reaches the groove 23 while being guided by the guide surface 24a of the guide protrusion 24, the product lead 12 reaches the groove 21 without contacting the guide surface 22a of the guide protrusion 22, In the worst case, even if the positioning lead holding portion 29 rubs against the positioning lead portion 13, the product lead holding portion 28 does not rub against the product lead portion 12.

  Therefore, as shown in FIG. 4D, when the lead frame 10 is placed on the lower cavity block 20 in the resin molding step, the positioning lead holding portion 29 lowers the positioning lead portion 13. The product lead holding portion 28 for receiving and holding the product lead portion 12 by receiving and holding it at a predetermined position of the mold does not require a configuration for positioning the product lead portion 12, and the product leads to the cavity. The lead portion 12 can be positioned with high accuracy.

  Since the product lead holding portion 28 does not require a configuration for positioning the product lead holding portion 12, the difference value α between the groove portion 21 of the product lead holding portion 28 and the product lead portion 12 is the positioning lead. The holding portion 29 can be set wider than the difference value β between the positioning lead portion 13 and the product lead portion 12 so that the product lead portion 12 has a margin. The product lead portion 12 can be received and held without causing rubbing.

  Then, as shown in FIG. 4 (e), the lead frame 10 is two-staged by the guide of the pilot hole 11 by the pilot pin 31 and the guide of the positioning lead portion 13 that does not contribute to the product shape by the positioning lead holding portion 29. In a state where the lead frame 10 is inserted and set in the cavity block 20 so that the product lead portion 12 is not rubbed against the guide projection portion 22 with high precision positioning, the cavity block 25 provided in the upper die is lowered. Clamping and injection molding are performed.

  In this injection molding, the lead frame 10 inserted and set between the cavity blocks 20 and 25 of the resin mold has a highly accurate positioning lead portion 13 where the positioning lead holding portion 29 does not contribute to the product in the groove portion 23. By positioning and holding the lead frame 10, it is possible to prevent the lead frame 10 from being displaced due to the resin injection pressure, and the product lead portion 12 is not scratched or indented. Resin burrs do not occur, and high-precision resin molding becomes possible.

  In this embodiment, the positioning lead holding portion 29 receives and holds the positioning lead portion 13 to position the lead frame 10 with respect to the cavity block 20 in the longitudinal direction (X direction). In the state shown in FIG. 4E, the positioning hole 14 formed in the lead frame 10 is fitted into the cavity convex portion 15 so that the lead frame 10 is positioned in the short direction (Y direction) with respect to the cavity block 20. is doing.

  The positioning of the lead frame 10 with respect to the cavity block 20 in the X direction and the Y direction can also be performed by simultaneously positioning the X direction and the Y direction with the positioning holes 14.

  In the present embodiment, the width of the positioning lead portion 13 and the product lead portion 12 is shown as the same dimension with W as the width of the positioning lead portion 13 and the product lead portion 12 in order to simplify the description. Of course, different dimensions may be used, and in the padding line 26, the gap E between the distance between the left and right guide projections 24 and the lead width of the positioning lead 13 is determined by the left and right guide projections 22. The cavity block 20 may be formed so as to be narrower than the gap E1 between the distance between them and the lead width of the product lead portion 12.

  Further, it is not necessary to divide the cavity into a plurality of blocks having a cam mechanism as in the prior art, and the grooves 21 and 23 can be processed in the same process when the resin molding mold is processed into a product shape. Costs such as material costs and mold processing costs can be reduced.

  In addition, the removal process of resin burrs by sandblasting, water jet, air jet, or the like, which has been conventionally required for removing resin burrs, is unnecessary, and the effect of improving the production efficiency by reducing the number of semiconductor device manufacturing processes. Is also played.

  According to the present invention, when the lead frame is placed on the lower die, the X direction and the Y direction of the lead frame with respect to the cavity without causing friction between the product lead portion and the groove portion of the die. The position accuracy of the lead can be guaranteed at the same time, and the lead frame can be prevented from shifting due to the molding pressure during resin injection. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an embodiment of the present invention, where (a) is a top view of a lead frame, (b) is a plan view of a resin molding die, and (c) is a cross-sectional view taken along line X-X 'in (b). FIG. 1A is an enlarged view of the A ′ portion in FIG. 1B, and FIG. 1B is an enlarged view of the B ′ portion in FIG. Enlarged view of B 'portion in FIG. State diagram showing a process flow for inserting and setting a lead frame into the cavity block of the resin molding die of the present invention Schematic configuration diagram showing the mold opening state of a resin mold used in a conventional manufacturing method Outline perspective view of lower mold of resin mold used in conventional manufacturing method and lead frame to be inserted and set It explains the operation of a resin molding die used in a conventional manufacturing method, (a) is a plan view showing a mold open state of a mold with a lead frame inserted and set, (b) shows a state of mold clamping. Plan view

Explanation of symbols

10, 40 Lead frame 11 Pilot hole 12 Product lead part 13 Positioning lead part 14 Positioning hole 15 Cavity convex part 20 Cavity block (lower mold)
20a Main surface 20b Guide blocks 21, 23 Groove parts 22, 24 Guide protrusions 25 Cavity block (upper mold)
26 Parting line 28 Product lead holding part 29 Positioning lead holding part 31 Pilot pin 41 Cavity block 42 Connector block 43 Tie bar block 43a, 46a Cam part 44 Lower mold 45 Fixed block 46 Frame pressing block 47 Return spring 48 Upper mold

Claims (5)

In a resin molding mold in which a lead frame is disposed on a lower mold, and the upper mold is clamped to the lower mold and resin-molded on the lead frame, a product lead portion formed on the lead frame by the lower mold is provided. A resin molding die comprising: a product lead holding portion for receiving and holding; and a positioning lead holding portion for receiving and holding a positioning lead portion formed on the lead frame at a predetermined position of the lower die. The product lead holding portion and the positioning lead holding portion each have a groove portion for receiving the lead portion, and a protrusion portion disposed on both sides of the groove portion, and the protrusion portion of the positioning lead holding portion is the product lead. The resin molding die according to claim 1, wherein the resin molding die is set to be higher than a protruding portion of the holding portion. The product lead holding part and the positioning lead holding part respectively receive and hold the lead part on a lead receiving surface between opposing guide surfaces, and the positioning lead holding part between the guide surface and the positioning lead. A positioning gap is provided, an interference prevention gap is provided between the guide surface and the product lead in the product lead holding portion, and the positioning gap is set narrower than the interference prevention gap. The resin molding die according to claim 1 or 2. The product lead holding portion and the positioning lead holding portion receive and hold the lead portions on the lead receiving surfaces between the opposing guide surfaces, respectively, and the lead receiving surface width of the positioning lead holding portion and the positioning lead The difference value with a lead width is set smaller than the difference value between the lead receiving surface width in the said product lead holding part and the lead width of the said product lead, The any one of Claims 1-3 characterized by the above-mentioned. The resin molding die as described in the item. The angle formed between the guide surface and the lead receiving surface in the positioning lead holding portion is set to be narrower than the angle formed between the guide surface and the lead receiving surface in the product lead holding portion. Or the resin molding die of 4.

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