JP2010073794A - Lead frame with dissipation plate and method for manufacturing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead frame with a dissipation plate which improves the reliability of a semiconductor package, in regard to the lead frame with the dissipation plate in which the dissipation plate is jointed to a lead frame body by inserting a projection for joint formed in the dissipation plate to an opening for joint formed in a lead frame body and crushing and processing a head of the projection for joint, and to provide a method for manufacturing the lead frame with the dissipation plate. <P>SOLUTION: The lead frame with the dissipation plate includes a thin wall part 2t around an opening 2h for joint in a lead frame body 2. The method for manufacturing the lead frame with the dissipation plate includes: a step of forming the opening 2h for joint in the lead frame body 2 and forming the thin wall part 2t around the opening 2h for joint; and a step of mutually jointing the lead frame body 2 and a dissipation plate 3 by inserting a projection 3p for joint of the dissipation plate to the opening 2h for joint of the lead frame body 2 and crushing and processing the head of the projection 3p for joint. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

    The present invention is directed to a lead frame for a semiconductor device, and more specifically, a bonding protrusion formed on a heat sink is fitted into a bonding hole formed in a lead frame body, and the head of the bonding protrusion is crushed. Thus, the present invention relates to a lead frame with a heat sink formed by coupling a heat sink to a lead frame main body, and a manufacturing method thereof.

    2. Description of the Related Art Conventionally, lead frames used in high-power semiconductor devices, in particular, use a heat sink made of a copper alloy or the like with good thermal conductivity to efficiently dissipate heat generated from the semiconductor chip. A so-called lead frame with a heat sink, which is joined to the main body, is used.

  The lead frame with a heat sink described above is composed of a lead frame main body having an expected shape with inner leads and the like, and a heat sink having an expected shape corresponding to the lead frame main body. The lead frame body and the heat sink are connected by caulking to each other by inserting the joint protrusion formed on the heat sink into the joint hole formed in and then crushing (caulking) the head of the joint protrusion. (For example, refer to Patent Document 1).

  In the conventional lead frame A with a heat sink shown in FIGS. 8 to 10, the lead frame main body L is provided with a pair of support portions Ls and Ls in which bonding holes Lh are formed together with inner leads Li, Li,. On the other hand, the heat sink H of the lead frame A with the heat sink is provided with a pair of mounting tabs Ht and Ht formed with bonding protrusions Hp.

Further, in the lead frame A with a heat sink, as shown in FIGS. 10 (a) and 10 (b), a bonding projection Hp is formed on the mounting tab Ht of the heat sink H, and then as shown in FIG. 10 (c). After inserting the joining projection Hp of the heat sink H into the joining hole Lh of the lead frame body L, the head of the joining projection Hp is crushed as shown in FIG. The main body L and the heat sink H are caulked and joined together.
JP 09-186285 A

    By the way, in the conventional lead frame A with a heat sink as described above, the lead frame main body L and the heat sink H are caulked and joined by crushing the heads of the joint protrusions Hp inserted into the joint holes Lh. Therefore, the bonding projection Hp of the heat sink H is formed higher than the plate thickness of the lead frame main body L, and the dimension of the bonding projection Hp is further increased as the plate thickness of the lead frame main body L increases. Must be set.

  Here, the joining protrusion Hp on the heat sink H is pressed at a predetermined portion of the heat sink H, and more specifically, pressure is applied from the back surface side of the heat sink H in the press device to perform crushing such as die forging. By carrying out, it is molded into the desired shape.

  For this reason, in order to form the above-mentioned joining protrusion Hp high, it is necessary to carry out a crushing process on the crushing region Ha (see FIG. 10B) of the heat sink H over a deep and wide range. As the crushing process is performed, the periphery of the joining projection Hp on the mounting tab Ht of the heat radiating plate H is deformed so as to bulge outward, and a clearance with the adjacent inner leads Li, Li. It becomes difficult.

  Further, by performing deep crushing processing on the crushing region Ha, warping deformation occurs in the heat sink H due to internal stress accompanying plastic processing, and in the resin sealing process at the time of manufacturing a semiconductor package, a mold mold Intrusion of the sealing resin into the gap between the heat sink and the heat sink causes inconveniences such as adhesion of the sealing resin to the back surface (surface exposed from the package) of the heat radiating plate H.

  An object of the present invention is to provide a lead frame with a heat sink that can improve the reliability of a semiconductor package in view of the above situation, and a manufacturing method thereof.

    In order to achieve the above object, a lead frame with a heat dissipation plate according to the invention of claim 1 is configured such that a bonding protrusion formed on the heat dissipation plate is fitted into a bonding hole formed in the lead frame body, and the head of the bonding protrusion is formed. A lead frame with a heat sink formed by crushing the portion to couple a heat sink to the lead frame main body, characterized in that a thin portion is provided around the bonding hole in the lead frame main body.

  The lead frame with a heat sink related to the invention of claim 2 is the lead frame with a heat sink related to the invention of claim 1, wherein the thin portion of the lead frame main body is formed flush with one surface of the lead frame main body. It is characterized by being.

  A lead frame with a heat sink related to the invention of claim 3 is characterized in that, in the lead frame with a heat sink related to the invention of claim 1 or claim 2, the thin portion of the lead frame main body is formed by pressing. Yes.

  A lead frame with a heat sink related to the invention of claim 4 is characterized in that, in the lead frame with a heat sink related to the invention of claim 1 or 2, the thin portion of the lead frame main body is formed by etching. Yes.

  According to a fifth aspect of the present invention, there is provided a method of manufacturing a lead frame with a heat sink, wherein a bonding protrusion formed on a heat sink is fitted into a bonding hole formed in a lead frame body, and a head portion of the bonding protrusion is crushed. A method of manufacturing a lead frame with a heat sink that couples a heat sink to the lead frame main body, forming a bonding hole in the lead frame main body, and forming a thin portion around the bonding hole; The step of fitting the lead frame main body and the heat radiating plate to each other by inserting the joint projection of the heat radiating plate into the joint hole of the lead frame main body and crushing the head of the joint protrusion. It is a feature.

  According to a sixth aspect of the present invention, there is provided a method for manufacturing a lead frame with a heat sink, wherein the thin portion of the lead frame main body is connected to one surface of the lead frame main body. It is characterized by being formed flush.

  A method for manufacturing a lead frame with a heat sink related to the invention of claim 7 is the method of manufacturing a lead frame with a heat sink related to the invention of claim 5 or claim 6, wherein the thin portion of the lead frame main body is formed by press working. It is characterized by that.

  A method for manufacturing a lead frame with a heat sink related to the invention of claim 8 is the method for manufacturing a lead frame with a heat sink related to the invention of claim 5 or claim 6, wherein the thin portion of the lead frame body is formed by etching. It is characterized by that.

In the lead frame with a heat sink according to the first aspect of the present invention, since the thin portion is formed around the joint hole in the lead frame main body, the height of the joint protrusion required for the caulking connection between the lead frame main body and the heat sink is high. Therefore, the crushing process for forming the joining projections on the heat sink can be performed in a shallow and narrow “crushing region”.
As described above, since the “crushing region” is suppressed in a shallow and narrow range, the phenomenon that occurs due to the crushing process for forming the joining protrusion, the heat sink deforms to bulge outward, Thus, it is possible to prevent as much as possible a phenomenon in which the heat sink is warped and deformed due to internal stress, and it is possible to improve the reliability of the semiconductor package including the lead frame with the heat sink according to the present invention as a constituent element.

  In the lead frame with a heat sink related to the invention of claim 2, the thin portion of the lead frame main body is formed flush with one surface of the lead frame main body, so that it is necessary for caulking coupling between the lead frame main body and the heat sink. Since the height dimension of the joining projections can be suppressed as much as possible, and the “crushing region” can be suppressed in a shallow and narrow range, the phenomenon that the heat sink deforms to bulge outward, It is possible to prevent as much as possible the phenomenon of warping deformation of the heat sink, and it is possible to improve the reliability of the semiconductor package including the lead frame with the heat sink according to the present invention as a component.

  In the lead frame with a heat sink related to the invention of claim 3, since the thin portion of the lead frame body is formed by pressing, the formation of the thin portion in the lead frame body is extremely possible by adopting the existing press processing. In addition, the series of steps can be performed without stopping by pressing from the desired lead frame pattern formation to the thin-walled portion formation. It becomes possible to further increase the productivity of the frame.

  In the lead frame with a heat sink according to the invention of claim 4, since the thin portion of the lead frame body is formed by etching, the formation of the thin portion in the lead frame body is extremely possible by adopting the existing etching processing. The process from the formation of the desired lead frame pattern to the formation of the thin-walled portion can be carried out by etching without stopping the above series of steps, thereby providing a lead with a heat sink. It becomes possible to further increase the productivity of the frame.

According to a fifth aspect of the present invention, there is provided a method of manufacturing a lead frame with a heat sink, a step of forming a bonding hole in the lead frame main body and forming a thin portion around the bonding hole, and a bonding hole of the lead frame main body. And inserting the protrusions for joining the heat sink into the joint, crushing the heads of the joint protrusions, and joining the lead frame main body and the heat sink to each other. It is possible to suppress the height of the bonding projections necessary for the coupling, and the crushing process for forming the bonding projections on the heat sink should be carried out in a shallow and narrow “crushing region”. Become.
As described above, since the “crushing region” is suppressed in a shallow and narrow range, the phenomenon that occurs due to the crushing process for forming the joining protrusion, the heat sink deforms to bulge outward, Thus, it is possible to prevent as much as possible a phenomenon in which the heat sink is warped and deformed due to internal stress, and it is possible to improve the reliability of the semiconductor package including the lead frame with the heat sink according to the present invention as a constituent element.

  In the method of manufacturing a lead frame with a heat sink related to the invention of claim 6, the lead frame main body and the heat sink are formed by forming the thin portion of the lead frame main body flush with one surface of the lead frame main body. As a result, the height of the joint projection required for crimping can be reduced as much as possible, and the “crushing area” can be kept shallow and narrow so that the heat sink bulges outward. It is possible to prevent as much as possible the phenomenon of deformation and the occurrence of warp deformation of the heat sink, and it is possible to improve the reliability of the semiconductor package including the lead frame with the heat sink according to the present invention as a component. .

  In the method of manufacturing a lead frame with a heat sink according to the invention of claim 7, the thin portion of the lead frame main body is formed by press working, so by adopting the existing press working, the thin portion of the lead frame main body is It can be easily formed, and the series of steps can be carried out without stopping by pressing from the desired lead frame pattern formation to the formation of the thin-walled portion. Productivity of a lead frame with a plate can be further increased.

  In the method of manufacturing a lead frame with a heat sink according to the invention of claim 8, the thin portion of the lead frame body is formed by etching, so that the thin portion of the lead frame body is removed by adopting the existing etching process. It can be easily formed, and from the formation of the desired lead frame pattern to the formation of the thin-walled portion can be performed without stopping the above-described series of steps by etching. Productivity of a lead frame with a plate can be further increased.

    Hereinafter, a lead frame with a heat dissipation plate and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings showing embodiments.

  1 to 4 show an embodiment of a lead frame with a heat sink according to the present invention. The lead frame 1 with a heat sink includes a lead frame body 2 and a heat sink 3 that are caulked to each other. Has been.

  As shown in FIG. 1 and FIG. 2, the lead frame main body 2 is formed of a desired lead by a known means such as etching or pressing (punching) from a thin plate made of copper and having a thickness of about 0.2 mm. The inner leads 2i, 2i..., The outer leads 2o, 2o... And the dam bars 2d, 2d... Are further bent and plated at predetermined locations.

  The lead frame body 2 is provided with a pair of left and right support portions 2s, 2s for coupling the heat sink 3, and the substantially rectangular support portions 2s, 2s are respectively provided with bonding projections 3p described later. A bonding hole 2h to be inserted is formed through.

  Further, each support portion 2s of the lead frame body 2 is formed with a thin portion 2t around the bonding hole 2h, and the thin portion 2t is a back surface 2b (lead frame) of the lead frame body 2 (support portion 2s). The surface 2a of the main body 2 is flush with the bonding hole 2h, and a circular recess 2r is defined on the surface 2a of the support 2s.

  Incidentally, in the present embodiment in which the plate thickness of the lead frame main body 2 is about 0.2 mm, the plate thickness of the thin portion 2t is set to about 0.1 mm, and the diameter of the bonding hole 2h is about 0 mm. 0.5 mm, and the diameter of the recess 2 r is set to about 1.2 mm.

  On the other hand, as shown in FIGS. 1 and 3, the heat radiating plate 3 is a plate-like member formed of a copper alloy having a high thermal conductivity and a heat radiating effect, and a main body 3m having a substantially rectangular shape, A pair of mounting tabs 3t and 3t having a substantially rectangular shape and projecting from the left and right side edges of the main body 3m are provided.

  In the pair of mounting tabs 3t and 3t, bonding protrusions 3p and 3p corresponding to the pair of bonding holes 2h and 2h in the lead frame main body 2 are respectively known in the crushing region 3a of the mounting tab 3t. The projection is formed by crushing.

  Incidentally, in this embodiment, the diameter of the bonding projection 3p is set to about 0.4 mm, and the height dimension of the bonding projection 3p is the height of the bonding hole 2h in the lead frame body 2 (that is, a thin wall). The thickness of the portion 2t is set to about 0.35 mm, which is 0.1 mm plus a height of 0.25 mm necessary for crushing the head.

  As shown in FIGS. 4A and 4B, the lead frame main body 2 and the heat radiating plate 3 configured as described above are provided with bonding protrusions 3p of the heat radiating plate 3 in the bonding holes 2h of the lead frame main body 2, respectively. After the insertion, the head of the joining projection 3p is crushed so that the heat radiating plate 3 is integrally crimped to the back surface 2b of the lead frame main body 2 to form the desired lead frame 1 with a heat radiating plate. Yes.

  Below, the manufacturing method of the lead frame 1 with a heat sink mentioned above is demonstrated in detail, referring FIGS.

  First, as shown in FIG. 5 (a), a heat radiating plate 3 (base material 3 ') having a desired planar shape formed from a copper alloy plate is prepared, and then mounted as shown in FIG. 5 (b). A known pressing process (crushing process) is applied to the crushing region 3a of the tab 3t, and a joining projection 3p having a predetermined shape is formed on the mounting tab 3t, thereby completing the heat radiating plate 3 exhibiting the desired shape.

  On the other hand, as shown in FIGS. 6A to 6F, a lead frame body 2 having a desired shape is formed by forming a bonding hole 2h and a thin portion 2t in the support portion 2s of the lead frame body 2. To do.

  Specifically, as shown in FIGS. 6A and 6B, a support hole 2s of the lead frame body 2 is formed with a small diameter punch Pa so as to penetrate through a bonding hole 2h having a diameter of about 0.5 mm. Next, as shown in FIGS. 6C and 6D, a large-diameter punch Pb is pressed down from the front surface 2a of the support portion 2s, so that the thin portion 2t having a plate thickness of about 0.1 mm becomes the back surface 2b of the support portion 2s. And a circular recess 2r is formed on the surface 2a of the support portion 2s.

  After that, as shown in FIGS. 6 (e) and 6 (f), the metal surplus generated in the inner periphery of the joining hole 2h due to the crushing process of the punch Pb is punched using a small diameter punch Pc. The lead frame main body 2 having the desired shape is completed by finishing the bonding hole 2h to an accurate dimension.

  As described above, after the lead frame main body 2 is completed, as shown in FIG. 5 (c), the joining protrusion 3p of the heat radiating plate 3 is inserted into the joining hole 2h of the support portion 2s of the lead frame main body 2. Then, as shown in FIG. 5 (d), by crushing the heads of the bonding projections 3p, the back surface 2b of the lead frame body 2 and the heat radiating plate 3 are integrally crimped and joined together. As a result, the lead frame 1 with a heat sink is completed.

  Incidentally, as shown in FIG. 7A, the crushing process of the head portion of the joining projection 3p is performed after the joining projection 3p of the heat radiating plate 3 is inserted into the joining hole 2h of the lead frame body 2, as shown in FIG. As shown in (b) and (c), it is carried out by pressing the crushing punch P. The recess Pr in the crushing punch P has an inner diameter of about 0.7 mm and a height (depth). It is set to about 0.15 mm.

  As described above, according to the lead frame 1 with the heat sink and the manufacturing method of the lead frame 1 with the heat sink according to the present invention, the back surface 2b of the lead frame main body 2 is provided around the bonding hole 2h in the lead frame main body 2. By forming the flush-walled portion 2t, the height dimension of the joining projection 3p necessary for caulking coupling between the lead frame body 2 and the heat sink 3 can be suppressed.

  Specifically, in a conventional lead frame with a heat sink using a lead frame body with a thickness of 0.2 mm, the height of the joining protrusion on the heat sink is reduced to a thickness of 0.2 mm of the lead frame body, and the head is crushed. In the above-described embodiment of the present invention, the lead frame main body 2 has a thin wall thickness of about 0.1 mm, whereas a dimension of about 0.45 mm, which is a height required for processing of 0.25 mm, is required. By forming the portion 2t, the height of the bonding projection 3p in the heat radiating plate 3 is suppressed to about 0.35 mm, and the size can be reduced by 25 to 30% compared to the conventional case.

  As described above, since the height of the bonding protrusion 3p on the heat radiating plate 3 is kept low, the crushing process for forming the bonding protrusion 3p may be performed in a shallow and narrow crushing region 3a. As a result, the outward deformation of the heat sink 3 (mounting tab 3t) accompanying the crushing process is reduced by about 30% compared to the conventional lead frame with a heat sink, and the clearance between the adjacent inner leads 2i, 2i. Therefore, the degree of freedom in designing the lead frame body is increased, and the semiconductor package can be further downsized.

  Further, as described above, the crushing process for forming the bonding projections 3p may be performed in the crushing region 3a in a shallow and narrow range, so that warping deformation of the heat sink 3 accompanying the crushing process is suppressed as much as possible. It is possible to prevent inconveniences such as adhesion of the sealing resin to the back surface (surface exposed from the package) of the heat sink 3 in the resin sealing process at the time of manufacturing the semiconductor package. It becomes possible to improve the reliability of the semiconductor package including the frame 1 as a constituent element.

  Further, according to the above-described configuration of the present invention, the thinned portion 2t that is flush with the back surface 2b of the lead frame body 2 is formed around the bonding hole 2h in the lead frame body 2, so 4 and 5, the head of the protrusion 3p is accommodated in a recess 2r defined on the surface 2a of the lead frame main body 2 (support portion 2s) and protrudes greatly from the surface 2a of the lead frame main body 2. Therefore, when manufacturing the semiconductor package, it becomes difficult for the loop of the bonding wire to come into contact with the bonding projection 3p, thereby improving the reliability of the semiconductor package having the lead frame 1 with the heat sink as a constituent element. It becomes possible.

  Further, in the embodiment described above, as shown in FIG. 6, the thin portion 2t of the lead frame main body 2 is formed by press working. In contrast, the thin portion 2t can be formed very easily.

  In the embodiment described above, as shown in FIG. 6, the thin portion 2t of the lead frame body 2 is formed by pressing. However, as another embodiment, the thin portion 2t of the lead frame body 2 is formed. It is possible to form the thin-walled portion 2t with respect to the lead frame main body 2 very easily by adopting the existing etching processing.

  In the above-described embodiment, a thin copper plate is used for the lead frame body 2 constituting the lead frame 1 with a heat sink, but ALLOY 42 (iron alloy containing 42% Ni), aluminum plate, etc. Various metal materials that satisfy the requirements for the lead frame can be employed.

  Similarly, in the above-described embodiment, a copper alloy plate material is employed for the heat radiating plate 3 constituting the lead frame 1 with a heat radiating plate. However, a thermal conductivity that is recognized as a heat radiating effect such as an aluminum plate material. It is possible to adopt various metal materials having high levels.

  In the above-described embodiment, the lead frame body 2 constituting the lead frame 1 with the heat sink is formed from a thin copper plate having a thickness of about 0.2 mm. The thickness is not limited to only about 0.2 mm in the embodiment, and a thin plate having an appropriate thickness according to the specifications of the semiconductor device such as about 0.125 mm or about 0.25 mm may be employed. Is possible.

  Further, in the above-described embodiment, the thin portion 2t having a plate thickness of about 0.1 mm is formed on the lead frame body 2 having a plate thickness of about 0.2 mm, while the heat sink 3 has a height of about 0.35 mm. However, the thickness of the thin portion 2t and the height of the bonding projection 3p are appropriately set according to the material and thickness of the lead frame main body 2 and the heat radiating plate 3. It goes without saying that it is possible.

(a) And (b) is the whole top view and whole side view which show one Example of the lead frame with a heat sink concerning this invention. (a) is a whole top view of the lead frame main body which comprises the lead frame with a heat sink concerning the present invention, (b) is a bb line sectional view in (a). (a) is a whole top view of the heat sink which comprises the lead frame with a heat sink concerning this invention, (b) is the bb sectional view taken on the line in (a). (a) And (b) is a cross-sectional view of the main part showing a state in which the joining projection of the heat sink is inserted into the joining hole of the lead frame body of the lead frame with the heat sink according to the present invention, The principal part sectional drawing which shows the state which crushed the head and combined the lead frame main body and the heat sink with each other. (a)-(d) is principal part sectional drawing which shows the manufacturing process of the lead frame with a heat sink concerning the present invention. (a)-(f) is principal part sectional drawing which shows the process of forming the hole for a lead frame main body which comprises the lead frame with a heat sink, and the thin part which concern on this invention. (a)-(c) is principal part sectional drawing which shows the process of couple | bonding the lead frame main body and heat sink of the lead frame with a heat sink concerning the present invention. (a) And (b) is the whole top view and whole side view which show the conventional lead frame with a heat sink. (a) The whole top view of the lead frame main body which comprises the conventional lead frame with a heat sink, (b) is the whole top view of the heat sink which comprises the conventional lead frame with a heat sink. (a) And (b) is principal part sectional drawing which shows the state which inserted the protrusion for joining of the heat sink in the hole for joining of the lead frame main body in the conventional lead frame with a heat sink, and the head of the protrusion for joining The principal part sectional drawing which shows the state which crushed and processed the lead frame main body and the heat sink.

Explanation of symbols

1 ... Lead frame with heat sink,
2 ... Lead frame body,
2a ... surface,
2b ... back side,
2i ... Inner lead,
2s ... support part,
2h ... hole for joining,
2t ... Thin part,
2r ... recess,
3 ... heat sink,
3m ... body,
3t ... Mounting tab,
3p ... projection for bonding,
3a: Crushing region.

Claims (8)

A joining projection formed on the heat dissipation plate is inserted into a joining hole formed on the leadframe body, and the head of the joining projection is crushed to bond the heat dissipation plate to the leadframe body. A lead frame with a heat sink,
A lead frame with a heat sink, wherein a thin portion is provided around a bonding hole in the lead frame main body. 2. The lead frame with a heat sink according to claim 1, wherein the thin portion of the lead frame body is formed flush with one surface of the lead frame body. The lead frame with a heat sink according to claim 1 or 2, wherein the thin portion of the lead frame body is formed by pressing. The lead frame with a heat sink according to claim 1 or 2, wherein the thin portion of the lead frame body is formed by etching. A heatsink that joins the heatsink to the leadframe body by inserting a jointing protrusion formed on the heatsink into a jointing hole formed in the leadframe body and crushing the head of the jointing protrusion. A method of manufacturing a lead frame with
Forming the bonding hole in the lead frame body, and forming a thin portion around the bonding hole;
Inserting the joining projection of the heat sink into the joining hole of the lead frame body, crushing the head of the joint projection and coupling the lead frame body and the heat sink to each other;
The manufacturing method of the lead frame with a heat sink characterized by including. 6. The method for manufacturing a lead frame with a heat sink according to claim 5, wherein the thin portion of the lead frame body is formed flush with one surface of the lead frame body. The method for manufacturing a lead frame with a heat sink according to claim 5 or 6, wherein the thin portion of the lead frame body is formed by pressing. The method for manufacturing a lead frame with a heat sink according to claim 5 or 6, wherein the thin portion of the lead frame body is formed by etching.

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