Metal foil element and method for manufacturing power semiconductor device

Abstract

To provide a technique capable of appropriately picking up a metal foil element.SOLUTION: The method of manufacturing the metal foil element includes a cutting step of cutting the metal foil 14 along a scheduled cutting line, and a pickup step of picking up the element formation region 15 as the metal foil element 7 after the cutting step. The cutting line 17 includes an element forming line 17-1 and a surplus region dividing line 17-2 for dividing the surplus region into a plurality of regions so that the expanding step can be performed. The element forming region 15 is connected to the outer periphery of the metal foil 14 via the surplus region dividing line 17-2 in at least two places.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a metal foil element and a power semiconductor device. [Background technology]

[0002] Metal foil elements are used in a variety of situations. For example, Non-Patent Document 1 describes a technology related to power modules called a die-top system. Non-Patent Document 1 describes a method of attaching a copper foil having a special shape to a die (chip) via a sintering paste. Specifically, the copper foil described is roughly rectangular, but has a notch on one side. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Heraeus Electronics, Die Top System (DTS) - Get the most out of your power module, Internet (URL: https: / / www.heraeus.com / en / het / products_and_solutions_het / material_systems / die_top_system / dts_page.html) Summary of the Invention [Problem to be solved by the invention]

[0004] As a means for producing a metal foil element having a special shape (for example, a shape other than a rectangle), a hollowing process such as punching can be considered. In this case, a metal foil is first prepared. Then, the metal foil is cut out along the shape of the metal foil element. Specifically, the metal foil is cut along the shape of the metal foil element, and the metal foil element is picked up after cutting.

[0005] However, when hollowing is used, the metal foil element may come into contact with the excess portion of the metal foil during pickup, making it impossible to properly pick up the element.

[0006] Even if the metal foil element does not have a special shape, when producing multiple metal foil elements from a single metal foil, if the regions that will become the metal foil elements are set apart from each other, hollowing out is usually considered, which can cause the same problems as in the case of a special shape.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide a technique that allows metal foil elements to be picked up appropriately. [Means for solving the problem]

[0008] In one aspect, a method for manufacturing a metal foil element according to the present invention includes a cutting step of setting lines to cut on a metal foil and cutting the metal foil along the lines to cut. The lines to cut include element formation lines corresponding to the periphery of an element formation region and excess region dividing lines that divide an excess region, which is a region other than the element formation region, into multiple regions. The element formation region has a shape other than a rectangle. The element formation region is connected to the periphery of the metal foil via the lines to cut at least two places.

[0009] In another aspect, a method for manufacturing a metal foil element according to the present invention includes a cutting step of setting lines to cut on the metal foil and cutting the metal foil along the lines to cut. The lines to cut include element formation lines corresponding to the periphery of the element formation region and excess region dividing lines that divide the excess region, which is a region other than the element formation region, into multiple regions. A plurality of element formation regions are set apart from each other. Each of the multiple element formation regions is connected to the periphery of the metal foil via the lines to cut at least two places. [Effects of the Invention]

[0010] According to the present invention, a technique is provided that allows metal foil elements to be picked up appropriately. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a power semiconductor device. [Figure 2] FIG. 2 is a plan view showing an example of a metal foil element. [Figure 3] FIG. 3 is a cross-sectional view schematically showing the cutting step. [Figure 4] FIG. 4 is a plan view schematically showing the cutting step. [Figure 5] FIG. 5 is a schematic cross-sectional view showing the expanding step and the picking up step. [Figure 6] FIG. 6 is a schematic cross-sectional view showing a method for manufacturing a power semiconductor device. [Figure 7] FIG. 7 is a plan view showing a layout of lines to cut according to the first modification. [Figure 8] FIG. 8 is a plan view showing a layout of lines to cut according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a method for manufacturing a metal foil element according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiment, as an example, a case where the metal foil element is used in a power semiconductor device using a die-top system will be described. However, the use of the metal foil element manufactured by this embodiment is not limited to such use.

[0013] First, the configuration of a power semiconductor device manufactured using a metal foil element will be described. Fig. 1 is a cross-sectional view showing a power semiconductor device 1 using a metal foil element 7 according to this embodiment. This power semiconductor device 1 generally includes a substrate 2, a power semiconductor element 5, and a metal foil element 7.

[0014] The substrate 2 is an insulating substrate made of, for example, ceramic or the like. A metal layer 3 is formed on the substrate 2 as wiring. Furthermore, a pad 4 and a power semiconductor element 5 are arranged on the metal layer 3. The power semiconductor element 5 is a semiconductor chip.

[0015] The metal foil element 7 is adhered to the power semiconductor element 5 via a conductive adhesive layer 6. The metal foil element 7 is also connected to the pad 4 via a wire 8. With this configuration, the metal foil element 7 can promote heat dissipation from the power semiconductor element 5. The power semiconductor element 5 can also be electrically connected to the pad 4 via the metal foil element 7. Another advantage of this configuration is the reliability of wire bonding. That is, the difference in the linear expansion coefficient between the metal foil element 7 and the wire 8 is usually smaller than the difference in the linear expansion coefficient between the power semiconductor element 5 and the wire 8. Therefore, by using the metal foil element 7, the reliability of wire bonding can be improved compared to when the wire 8 is directly bonded to the power semiconductor element 5.

[0016] Fig. 2 is a plan view showing an example of the metal foil element 7. As shown in Fig. 2, the metal foil element 7 has a special shape. Specifically, the metal foil element 7 has a shape other than a rectangle. More specifically, the metal foil element 7 has a rectangular shape with a notch 7-1 formed on one side.

[0017] In this embodiment, a manufacturing method is devised for manufacturing the metal foil element 7. The manufacturing method for the metal foil element 7 will be described below.

[0018] The method for manufacturing the metal foil element 7 according to this embodiment includes a cutting step (step S1), an expanding step (step S2), and a picking up step (step S3). Each step will be described in detail below.

[0019] (Step S1) Cutting process Fig. 3 is a cross-sectional view schematically showing the cutting step, and Fig. 4 is a plan view schematically showing the cutting step.

[0020] First, as shown in FIGS. 3(a) and 4(a), a ring frame 12 to which a dicing tape 9 is attached is prepared. Then, a metal foil 14 is placed on the dicing tape 9. In this embodiment, the metal foil 14 is provided as a laminate 11 with a bonding film-like material 13. That is, the laminate 11 is placed on the dicing tape 9. The laminate 11 is placed on the dicing tape 9 so that the metal foil 14 faces upward.

[0021] The bonding film-like material 13 is the part that will eventually be fired to become the adhesive layer 6 (see FIG. 1). The bonding film-like material 13 has a configuration in which, for example, a thermally conductive material having electrical conductivity is dispersed in a binder.

[0022] 3(b) and 4(b), a cutting line 17 is set on the metal foil 14. Then, the laminate 11 is cut along the cutting line 17. By simultaneously cutting the metal foil 14 and the bonding film-like material 13 in the laminate 11, not only can the metal foil 14 and the bonding film-like material 13 be cut simultaneously, but also the metal foil 14 and the bonding film-like material 13 can be cut into exactly the same shape.

[0023] 4(b), the cutting lines 17 have a complex shape. In detail, the cutting lines 17 include element formation lines 17-1 and excess region separation lines 17-2.

[0024] The element formation line 17-1 is a line for separating the element formation region 15 from its surrounding area. In other words, the element formation line 17-1 corresponds to the outer periphery of the element formation region 15. The element formation region 15 is the portion that will become the metal foil element 7. In this embodiment, a plurality of element formation regions 15 are set on the metal foil 14. The plurality of element formation regions 15 are spaced apart from each other. However, the element formation region 15 may be a single region.

[0025] On the other hand, the excess region dividing lines 17-2 are provided to enable the next process, the expanding process (step S2), to be carried out. The excess region dividing lines 17-2 divide the excess region 16 into multiple regions. The excess region 16 is the region of the metal foil 14 other than the element formation region 15.

[0026] The excess region separation lines 17-2 are set so that each element formation region 15 is connected to the outer periphery of the metal foil 14 at at least two locations via the intended cutting lines 17. That is, each element formation region 15 is connected to the outer periphery of the metal foil 14 at at least two locations via the excess region separation lines 17-2, or via the excess region separation lines 17-2 and the element formation lines 17-1 that separate other element formation regions 15. In the specific example shown in FIG. 4(b), the excess region separation lines 17-2 are set on multiple straight lines extending in a grid pattern. Each element formation region 15 is connected to both the excess region separation lines 17-2 extending vertically and the excess region separation lines 17-2 extending horizontally. With this configuration, each element formation region 15 is connected to the outer periphery of the metal foil 14 at at least two locations. As a result, the excess region 16 is divided into multiple regions.

[0027] In the expanding step described below, the cut laminate 11 is supported on a stretchable sheet, and the stretchable sheet is stretched. This widens the gap between the element formation region 15 and its surrounding region. Simply cutting the laminate 11 along the element formation line 17-1 would result in the element formation region 15 being surrounded by a closed excess region 16. If a closed excess region 16 exists outside the element formation region 15, the expanding step cannot widen the gap between the element formation region 15 and its surrounding region. In other words, the expanding step cannot be performed. In contrast, in this embodiment, the presence of the excess region separation line 17-2 prevents the formation of a closed region surrounding each element formation region 15. Therefore, the expanding step can widen the gap between each element formation region 15 and its surrounding region.

[0028] As described above, in this embodiment, the lines to cut 17 have a complex shape, making it difficult to use a means capable of cutting only in a linear direction (e.g., a rotary blade). Therefore, a cutting method capable of cutting at any position is used. Examples of such a cutting method include laser ablation, chemical etching, and plasma etching. Furthermore, if the cutting method is laser ablation, chemical etching, or plasma etching, as described in Modification 2 below, it is easy to form the first lines 17-2-1 or the second lines 17-2-2 at desired positions and in desired numbers to adjust the X / Y value for first lines 17-2-1 located on X straight lines extending along a first direction and second lines 17-2-2 located on Y straight lines extending along a second direction perpendicular to the first direction. Among these, since the chemical properties of the metal foil 14 and the bonding film-like material 13 are different, it is preferable to adopt laser ablation or plasma etching, as a method that does not rely on chemical action is desirable, and it is more preferable to adopt laser ablation, as it is easy to melt and cut the inorganic materials and metal materials contained in the bonding film-like material 13.

[0029] (Step S2) Expanding process Next, the expanding step is carried out. Figures 5(a) and 5(b) are schematic cross-sectional views showing the expanding step. As described above, in the expanding step, the extensible sheet 18 is stretched while the laminate 11 is supported on the extensible sheet.

[0030] Specifically, first, the cut laminate 11 is transferred from the dicing tape 9 onto the extensible sheet 18, and the laminate 11 is adhered to the extensible sheet 18 (FIG. 5(a)). Then, the extensible sheet 18 is stretched in the planar direction (FIG. 5(b)). This widens the gap between the cut portions. In other words, the gap between each element formation region 15 and its surrounding region widens.

[0031] (Step S3) Pick-up process Next, the element formation regions 15 are picked up as metal foil elements 7. FIG. 5(c) is a schematic cross-sectional view showing the pick-up process. As shown in FIG. 5(c), each element formation region 15 (metal foil elements 7) is pulled away from the extensible sheet 18 together with the bonding film-like material 13. At this time, since the gap between the metal foil element 7 and its surrounding area is widened in step S2, the metal foil element 7 is less likely to interfere with its surrounding area. In addition, the bonding film-like materials 13 are less likely to come into contact with each other. Therefore, it is possible to properly pick up the metal foil elements 7.

[0032] The metal foil element 7 according to this embodiment is obtained by the method described above. The obtained metal foil element 7 is used to manufacture the power semiconductor device 1 in accordance with the process (step S4) described below.

[0033] (Step S4) Manufacturing of power semiconductor devices FIG. 6 is a schematic cross-sectional view showing a method for manufacturing the power semiconductor device 1.

[0034] First, as shown in FIG. 6( a), a substrate 2 on which a power semiconductor element 5 is mounted is prepared. Then, a picked-up metal foil element 7 is bonded to the upper surface of the power semiconductor element 5. The metal foil element 7 is temporarily fixed to the power semiconductor element 5 via a bonding film material 13. Next, the bonding film material 13 is fired. This decomposes organic substances such as binders in the bonding film material 13. Furthermore, if the conductive thermally conductive material is metal particles as described below, the metal particles may fuse together to form an adhesive layer 6 made of the thermally conductive material. That is, as shown in FIG. 6( b), the metal foil element 7 is bonded to the power semiconductor element 5 via the adhesive layer 6. Note that if the power semiconductor element 5 is temporarily fixed to the substrate 2 (metal layer 3) using a separate firing material, the firing of the bonding film material 13 and the firing of the firing material between the power semiconductor element 5 and the substrate 2 may be performed simultaneously.

[0035] 6(c), the metal foil element 7 is connected to the pad 4 via the wire 8. In this way, the power semiconductor device 1 according to this embodiment is obtained.

[0036] The method for manufacturing the metal foil element 7 according to this embodiment has been described above, taking the case of manufacturing a power semiconductor device 1 as an example. According to this embodiment, a surplus area dividing line 17-2 of a specific shape is set on the cutting line 17 set in the cutting step (step S1). This makes it possible to carry out the expanding step (step S2). This makes it possible to avoid interference between the metal foil element 7 and the surrounding area in the picking up step (step S3), making it possible to easily pick up the metal foil element 7.

[0037] In this embodiment, the metal foil element 7 has a rectangular shape with a notch 7-1 formed on one side. However, the shape of the metal foil element 7 is not limited to this shape. When the metal foil element 7 has a special shape, hollowing out is generally considered. However, as mentioned above, simply hollowing out the metal foil element 7 does not effectively allow the expansion process to be carried out. Therefore, according to this embodiment, it is effective to set the excess region separation line 17-2 so that expansion can be carried out.

[0038] Generally, the "special shape" for which hollowing is considered is a shape other than a rectangle. Examples of the "shape other than a rectangle" include the following shapes: (1) A shape that cannot be formed by simply setting a plurality of straight lines extending from one periphery to the other periphery of the metal foil 14. (2) Shapes that cannot be processed by means that can only cut in a straight line, such as a rotary blade (3) Shape with curved sections (4) A shape with a convex or concave portion (notch) on one side

[0039] Here, to elaborate on (1) above, even if such a shape is a polygonal shape composed only of straight line portions, there will be a vertex that cannot be formed by the intersection of two or more straight lines connecting one end of the metal foil 14 to the other, or there will be a side that cannot be formed by straight lines connecting one end of the metal foil 14 to the other. Note that the term "vertex" also includes those with angles exceeding 180°.

[0040] On the other hand, even if the metal foil element 7 is simply rectangular (a rectangular shape without cutouts, etc.), when multiple element formation regions 15 are set apart from each other in the metal foil 14, it is common to adopt a hollowing process as a manufacturing method. However, as mentioned above, the expansion process cannot be performed if hollowing is simply performed. Therefore, even if the metal foil element 7 is rectangular, when multiple element formation regions 15 are set apart from each other, it is effective to set the excess region separation line 17-2 according to this embodiment so that expansion can be performed.

[0041] In this embodiment, the case where the laminate 11 is transferred from the dicing tape 9 to the extensible sheet 18 (see FIG. 5) in the expanding step (step S2) has been described. However, the dicing tape 9 itself may be used as the extensible sheet 18. Alternatively, the extensible sheet 18 may be laminated on the laminate 11 in advance in the cutting step (step S1). That is, the laminate 11 may be placed on the dicing tape 9 with the extensible sheet 18 interposed therebetween. In this case, after the cutting step (step S1) is completed, the dicing tape 9 is peeled off from the extensible sheet 18 before the expanding step (step S2). In the above cases, there is no need to transfer the laminate 11. The extensible sheet 18 may be laminated on the bonding film-like material 13 via an adhesive layer, or may be laminated directly on the bonding film-like material 13 without an adhesive layer interposed therebetween. When an adhesive layer is used, the adhesive layer can be formed using an energy ray-curable adhesive, or can be formed using an adhesive that does not harden with energy rays. In this embodiment, the metal foil 14 is placed on the dicing tape 9 as a laminate 11 with the bonding film-like material 13. However, a bonding composite sheet may be prepared in which the bonding film-like material 13 is pre-laminated on the dicing tape 9, and the metal foil 14 may be placed on the bonding film-like material 13 of the bonding composite sheet. The bonding composite sheet is convenient because it is provided as a set of the dicing tape 9 and the bonding film-like material 13.

[0042] The adhesive layer of the extensible sheet 18 generally lacks the strength to maintain its sheet shape, and therefore the extensible sheet 18 typically includes a substrate. Resin films are preferred as the substrate material, and resins for forming the resin film are preferably polyolefin resins such as polyethylene and polypropylene, olefin copolymers such as ethylene-methacrylic acid copolymer and ethylene-vinyl acetate copolymer, polybutylene terephthalate, cured films of urethane acrylate or urethane methacrylate, vinyl chloride, flexible polyester resins, etc., from the viewpoint of imparting flexibility suitable for expanding. These resins can also be used as ionomers by adding a metal ion crosslinking agent. Furthermore, these resins may be subjected to a modification treatment such as crosslinking by electron beam irradiation. Furthermore, if the substrate is self-adhesive, the substrate may also serve as the adhesive layer.

[0043] In this embodiment, the metal foil element 7 is used in a power semiconductor device 1 that utilizes a die-top system. However, the use of the metal foil element 7 is not limited to this. For example, the metal foil element 7 can also be suitably used as a heat dissipation material for other electronic components, such as semiconductor devices and batteries, that are used for purposes other than power control or conversion.

[0044] In this embodiment, the bonding film-like material 13 included in the laminate 11 together with the metal foil 14 is described as having a configuration in which an electrically conductive thermally conductive material is dispersed in a binder. This type of bonding film-like material 13 is suitable when the metal foil element 7 is used for a power semiconductor device such as a die-top system. A suitable example of this type of bonding film-like material 13 is a film-like sintered material containing metal particles, as described in WO 2019 / 163568. This film-like sintered material contains first metal particles, second metal particles, and a binder component. The first metal particles have an average particle diameter of 100 nm or less and a maximum particle diameter of 250 nm or less. The second metal particles have an average particle diameter of 1,000 to 7,000 nm, a minimum particle diameter of more than 250 nm, and a maximum particle diameter of 10,000 nm or less. The mass ratio of the first metal particles to the second metal particles is 0.1 or greater. Examples of metal species for the metal particles include silver, gold, copper, iron, nickel, aluminum, silicon, palladium, platinum, titanium, barium titanate, and oxides or alloys thereof, with silver and silver oxide being preferred. Examples of binder components that can be included in the film-shaped fired material together with the metal particles include resins. Examples of resins include acrylic resins, polycarbonate resins, polylactic acid, and polymers of cellulose derivatives, with acrylic resins being preferred.

[0045] However, the thermally conductive material contained in the bonding film-like material 13 does not necessarily have to be electrically conductive. Even when an insulating thermally conductive material is used, the metal foil element 7 can be suitably used for heat dissipation depending on the application. For example, other materials constituting the bonding film-like material 13 include film-like sintered materials containing inorganic thermally conductive materials, such as the green sheets for obtaining boron nitride sintered bodies described in WO2022 / 163646.

[0046] In this embodiment, the bonding film-like material 13 is baked to form the adhesive layer 6. That is, the bonding film-like material 13 is a baked film-like material, preferably a baked film-like material containing metal particles or an inorganic thermally conductive material. However, the bonding film-like material 13 does not necessarily have to be a baked material. For example, a curable adhesive sheet, such as an adhesive sheet made of an epoxy resin composition containing a thermally conductive material such as alumina or boron nitride, as described in JP 2014-156531 A, can also be used as the bonding film-like material 13. The curable adhesive sheet may contain a thermally conductive and electrically conductive material, such as the metal particles described above.

[0047] Alternatively, the metal foil 14 does not necessarily have to be processed in the state of the laminate 11. That is, the metal foil 14 may be processed independently. For example, if the bonding film-like material 13 is placed on the power semiconductor element 5 in advance, the metal foil element 7 can be attached to the power semiconductor element 5 even when the metal foil element 7 is processed independently.

[0048] (Variation 1) Next, a first modified example of the present embodiment will be described. This modified example relates to the layout of the lines to cut 17.

[0049] 7 is a plan view showing the layout of the lines to cut 17 according to Modification 1. As in the example shown in FIG. 4(b), in this modification, the element formation region 15 is rectangular with a notch on one side. However, in this modification, the surplus region dividing line 17-2 is connected to the element formation region 15 at a position different from the portion where the notch is provided.

[0050] 4(b), if the surplus region separation line 17-2 is connected to the element formation region 15 at the cutout, each surplus region 16 will have a complex shape after cutting. In contrast, according to this modification, each surplus region 16 will not have a complex shape after cutting, and therefore, contact between adjacent regions can be prevented in the expanding step (step S2).

[0051] (Variation 2) Next, a second modification of the present embodiment will be described. This modification also relates to the layout of the lines to cut 17.

[0052] Fig. 8 is a plan view showing the layout of the lines to cut 17 according to Modification 2. As shown in Fig. 8, in this modification, the excess area dividing lines 17-2 have first lines 17-2-1 located on X straight lines extending along a first direction and second lines 17-2-2 located on Y straight lines extending along a second direction perpendicular to the first direction. Here, 0.65≦X / Y≦1.5. Note that Fig. 8 shows an example in which both X and Y are 5.

[0053] According to this modification, since 0.65≦X / Y≦1.5, the spacing between the cut portions is more likely to be uniformly expanded in the expanding process (step S2). For example, if the gap between adjacent regions in a cut portion is excessively expanded, a large stress is generated in the extensible sheet 18 at that portion, making the extensible sheet 18 more likely to tear. On the other hand, if the expansion is insufficient, the metal foil element 7 is more likely to come into contact with its surrounding areas during the pick-up process (step S3). In particular, if the element formation region 15 has a special shape, the shapes of the multiple regions formed after cutting are likely to be nonuniform. Therefore, it is difficult to uniformly expand the gap between adjacent regions in the expanding process. However, according to this modification, since 0.65≦X / Y≦1.5, the cut portions are more likely to be uniformly expanded. As a result, the possibility of tearing the extensible sheet 18 is reduced, and the metal foil element 7 can be easily picked up. When the chip is rectangular, the dividing lines are formed in a grid pattern to match the chip shape, so the position and number of the dividing lines are necessarily determined. On the other hand, as shown in FIG. 4(b), since the excess region separation line 17-2 only needs to connect to the element formation region 15 at one point, it is not common to add unnecessary separation lines. In particular, when cutting the metal foil 14 using a rotary blade, forming extra separation lines tends to be avoided due to considerations such as increased processing time and blade wear. In the embodiment of FIG. 8, the X / Y ratio is intentionally set to approach 1 by providing extra excess region separation lines 17-2 (excess region separation lines 17-2 that do not connect to the element formation region 15) to achieve the above-mentioned effect. The X / Y ratio is preferably 0.7≦X / Y≦1.4, more preferably 0.8≦X / Y≦1.2, and even more preferably X / Y=1 (X and Y are equal).

[0054] In the example shown in FIG. 8, the excess region separating line 17-2 (first line 17-2-1) is connected to a cutout portion in the element forming region 15. However, as in Modification 1, the excess region separating line 17-2 may be connected to the element forming region 15 at a position other than the portion where the cutout is provided. In such a case, as described above, the individual shapes formed after cutting are not complex. However, the shapes are likely to be non-uniform between multiple regions, making it difficult to uniformly expand adjacent regions in the expanding process. However, according to Modification 2, 0.65≦X / Y≦1.5 is satisfied, making it easier to uniformly expand adjacent regions.

[0055] The present invention has been described above using embodiments and modifications. Representative configurations and effects of the present invention will be summarized below.

[0056] In one embodiment, a method for manufacturing a metal foil element 7 includes a cutting step of setting cutting lines 17 on a metal foil 14 and cutting the metal foil 14 along the cutting lines 17. The cutting lines 17 include element formation lines 17-1 corresponding to the periphery of the element formation region 15 and excess region separation lines 17-2 that separate the excess region 16, which is the region other than the element formation region 15, into multiple regions. The element formation region has a shape other than rectangular. The element formation region is connected to the periphery of the metal foil at least two locations via the cutting lines. According to this method, the excess region separation lines 17-2 separate the excess region 16 into multiple regions so that the expanding step can be performed. Therefore, even if the element formation region has a special shape, the expanding step can be performed after the cutting step. This reduces the likelihood of the metal foil element 7 coming into contact with its surrounding regions during pickup, allowing for proper pickup.

[0057] In another embodiment, a method for manufacturing a metal foil element 7 includes a cutting step of setting cutting lines 17 on the metal foil 14 and cutting the metal foil 14 along the cutting lines 17. The cutting lines 17 include element formation lines 17-1 corresponding to the periphery of the element formation regions 15 and excess region separation lines 17-2 that separate the excess region 16, which is the region other than the element formation regions 15, into multiple regions. A plurality of element formation regions 15 are set apart from one another. Each of the multiple element formation regions 15 is connected to the periphery of the metal foil 14 at at least two locations via the cutting lines 17. According to this method, the excess region 16 is separated into multiple regions by the excess region separation lines 17-2 so that the expanding step can be performed. Therefore, even if the multiple element formation regions are set apart from one another, expanding can be performed after the cutting step. This reduces the likelihood of the metal foil element 7 coming into contact with its surrounding regions during pickup, allowing for appropriate pickup.

[0058] In one embodiment, after the cutting step, an expanding step is performed in which the extensible sheet 18 is expanded while the metal foil is supported on the extensible sheet 18. The expanding step separates the element formation region 15 from the surrounding regions, which allows the element formation region 15 to be easily picked up.

[0059] In one embodiment, in the cutting step, the metal foil 14 is cut by laser ablation, chemical etching, or plasma etching, which allows cutting the metal foil at any desired position.

[0060] In one embodiment, the element formation region 15 is rectangular with a notch on at least one side. The excess region separation line 17-2 is connected to the element formation line 17-1 at a position different from the notch. With this configuration, the individual excess regions 16 after cutting do not have complex shapes, making it easier to prevent contact between adjacent regions.

[0061] In one embodiment, the excess region dividing lines 17-2 include first lines 17-2-1 located on X straight lines extending in a first direction and second lines 17-2-2 located on Y straight lines extending in a second direction perpendicular to the first direction. The ratio X / Y satisfies 0.65≦X / Y≦1.5. This configuration tends to make the shapes of the multiple regions formed after cutting uniform, which in turn tends to make the cut portions uniformly expand during the expanding process.

[0062] In one embodiment, the metal foil 14 is prepared as a laminate 11 with a bonding film-like material 13 containing a thermally conductive material. Then, in the cutting process, the laminate 11 is cut to cut the metal foil 14. With this configuration, a metal foil element 7 on which the bonding film-like material 13 is laminated can be obtained. Furthermore, by cutting the metal foil 14 and the bonding film-like material 13 simultaneously, not only can the metal foil 14 and the bonding film-like material 13 be cut simultaneously, but the metal foil 14 and the bonding film-like material 13 can also be cut into exactly the same shape. Then, the metal foil element 7 can be used as a heat dissipation material simply by placing the metal foil element 7 on a component that is to be heat dissipated.

[0063] In one embodiment, a metal foil element 7 is bonded to the power semiconductor element, thereby obtaining a power semiconductor device having a heat dissipation material. [Explanation of symbols]

[0064] 1 power semiconductor device, 2 substrate, 3 metal layer, 4 pad, 5 power semiconductor element, 6 adhesive layer, 7 metal foil element, 7-1 notch, 8 wire, 9 dicing tape, 10 base film, 11 laminate, 12 ring frame, 13 bonding film material, 14 metal foil, 15 element formation area, 16 excess area, 17 planned cutting line, 17-1 element formation line, 17-2 excess area separation line, 18 stretchable sheet

Claims

1. A cutting step of setting a cutting line on the metal foil and cutting the metal foil along the cutting line, The planned cutting line is an element formation line corresponding to the periphery of an element formation region; an excess region dividing line dividing an excess region, which is a region other than the element forming region, into a plurality of regions; the element formation region has a shape other than a rectangle, the element forming region is connected to the outer periphery of the metal foil via the cutting line at least at two points; Method for manufacturing metal foil elements.

2. A cutting step of setting a cutting line on the metal foil and cutting the metal foil along the cutting line, The planned cutting line is an element formation line corresponding to the periphery of an element formation region; an excess region dividing line dividing an excess region, which is a region other than the element forming region, into a plurality of regions; a plurality of the element formation regions are set apart from each other, each of the plurality of element forming regions is connected to the outer periphery of the metal foil via the cutting line at least at two locations; Method for manufacturing metal foil elements.

3. 3. A method for producing a metal foil element according to claim 1 or 2, comprising: The method further includes, after the cutting step, an expanding step of expanding the extensible sheet with the metal foil supported on the extensible sheet. Method for manufacturing metal foil elements.

4. 3. A method for producing a metal foil element according to claim 1 or 2, comprising: In the cutting step, the metal foil is cut by laser ablation, chemical etching, or plasma etching. Method for manufacturing metal foil elements.

5. 3. A method for producing a metal foil element according to claim 1 or 2, comprising: the element formation region has a rectangular shape with a notch provided on at least one side, the excess region dividing line is connected to the element formation region at a position different from a portion where the notch is provided; Method for manufacturing metal foil elements.

6. 3. A method for producing a metal foil element according to claim 1 or 2, comprising: The excess area dividing line is First lines located on X straight lines extending along a first direction; and second lines located on Y straight lines extending along a second direction perpendicular to the first direction, 0.65≦X / Y≦1.5; Method for manufacturing metal foil elements.

7. 3. A method for producing a metal foil element according to claim 1 or 2, comprising: The metal foil is prepared as a laminate with a bonding film-like material containing a thermally conductive material, In the cutting step, the metal foil is cut by cutting the laminate. Method for manufacturing metal foil elements.

8. manufacturing the metal foil element according to the method of claim 1 or 2; bonding the metal foil element to a power semiconductor element; Including, A method for manufacturing a power semiconductor device.

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