JP2006080300A - Lead frame and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a lead frame by which a gap can be narrowed between a frame element to be used as a component mounting part and a frame element adjacent to the frame element. <P>SOLUTION: After forming the blank of a lead frame which consists of arraying a plurality of frame elements including the component mounting part 101 at a prescribed pattern by punching, a part of frame elements 1C, 1D arranged on both the sides of the component mounting part 101 is deformed like a round shape in the plate thickness direction so as to shorten a distance between the component mounting part 101 and the adjacent frame element 102 which becomes a connected destination of a wire connected to a component mounted on the component mounting part, to form deformed works 1C1, 1D1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lead frame used for mounting a chip such as a semiconductor element or a semiconductor integrated circuit, and a manufacturing method thereof.

  In an electronic component including a semiconductor element such as a thyristor, a diode, or a MOSFET, or a chip such as a semiconductor integrated circuit, a lead frame is used in the manufacturing process in order to have a structure in which lead terminals are drawn from the chip.

  As shown in Patent Document 1, the lead frame has a structure in which a plurality of frame elements including a component mounting portion and a lead terminal portion are arranged in a predetermined pattern with a gap interposed therebetween. ing. This lead frame is formed by punching or etching a frame material made of a conductive plate.

For example, an electronic component manufacturing process using a lead frame is performed as follows.
First, a chip such as a semiconductor element or a semiconductor integrated circuit is attached to a component attachment portion of a lead frame by soldering or bonding using a die bonder. After the chip is attached, wiring wires are connected by a wire bonder. At that time, among the electrode portions of the chip attached to the component attachment portion, the electrode portion connected to the external circuit is wired to the lead terminal portion adjacent to the component attachment portion to which the chip is attached via a gap. It is connected via a wire.

  In addition, when a plurality of chips that are electrically connected to each other are attached to the lead frame, a plurality of component attachment portions are provided on the lead frame in a state of being adjacent to each other via a gap. A chip is attached to each of the electrodes, and predetermined electrodes of the chips respectively attached to a plurality of adjacent component attaching portions are connected by wiring wires.

  After the chip is attached to the lead frame and wiring is performed using a wire, a package made of a mold resin is formed so as to cover the chip and a part of the lead terminal portion connected to the chip via the wire. Thereafter, the connecting portion connecting the component attaching portion to the frame portion and the lead terminal portion are separated from the frame portion, thereby completing the electronic component.

  As described above, when configuring an electronic component having a structure in which a lead terminal is drawn out from a chip using a lead frame, between the chip attached to the component mounting portion of the lead frame and the lead terminal portion, or A plurality of chips are connected by wiring wires. The wiring wire connects between the chip and the lead terminal portion or between adjacent chips across the gap between the component mounting portion and the lead terminal portion or the gap between the plurality of component mounting portions. Therefore, in order to reduce the cost by shortening the length of the wire connecting each part as much as possible, the distance between the component mounting portion and the frame element adjacent to the component mounting portion or the distance between a plurality of component mounting portions is set. It is necessary to keep it as short as possible.

  In order to reduce the size of the electronic component by reducing the size of the package made of the mold resin, it is desirable that the distance between the component mounting portion and the frame element adjacent thereto be as short as possible.

  Furthermore, when the flowability of the resin is different between the front side and the back side of the lead frame when forming the package, if the distance between the frame elements of the lead frame is long (the gap between the frame elements is wide), In some cases, the resin cannot be completely filled in the mold and the appearance of the package is deteriorated.

  As described above, in the lead frame, it is desirable to make the gap between the component mounting portion and the lead terminal portion and the gap between the plurality of component mounting portions as narrow as possible, but the lead frame is formed by punching. In this case, if the distance D between the frame elements is set to be equal to or less than the plate thickness t, the punch for punching and the die are likely to be damaged, and therefore the distance between the frame elements cannot be set to be equal to or less than the plate thickness. For this reason, D≈t, and it is inevitable that the distance D between the frame elements becomes longer than necessary particularly when it is necessary to increase the thickness of the lead frame in order to pass a relatively large current.

  In some cases, a lead frame may be formed by etching. In this case as well, it is difficult to make the distance between the frame elements equal to or less than the plate thickness.

  Therefore, Patent Document 1 proposes a method of apparently shortening the distance between adjacent frame elements. In the method described in Patent Document 1, a frame material made of a conductive plate is punched out to form a lead frame semi-processed product having a plurality of frame elements such as a component mounting portion and a lead terminal portion, and then adjacent by a punch. The part facing the gap of the frame element is crushed, and the metal on both sides of the gap is moved in a direction to approach each other. Thus, after forming thin projections close to each other at adjacent ends of adjacent conductive portions, the shape is adjusted by cutting the tips of the projections, and flat plates are formed from adjacent ends of adjacent frame elements. A lead frame having a structure with protruding protrusions is obtained.

  The structure of the main part of an electronic component using a lead frame that has not been processed to reduce the distance between frame elements is shown in FIG. 12 (A), and adjacent frames by the method described in Patent Document 1 FIG. 12B shows the structure of the main part of an electronic component using a lead frame in which protrusions are formed at adjacent ends of the element. In these drawings, La is a component mounting portion, Lb is a lead terminal portion, and a gap G is formed between the component mounting portion La and the lead terminal portion Lb. T is a chip attached to the component attachment portion La, W is a wire having one end connected to the electrode of the chip T and the other end connected to the lead terminal portion Lb, and P is a package made of mold resin. In the case of the method shown in Patent Document 1, as shown in FIG. 12 (B), the metal moved by the punch protrudes at the adjacent ends of the component mounting portion La and the lead terminal portion Lb. La1 and Lb1 are formed, a reduced gap g ′ is formed between these protrusions, and the distance between the component mounting portion La and the lead terminal portion Lb is apparently shortened from D to d.

In Patent Document 2, after forming a semi-processed product of a lead frame provided with a deformed portion curved in the width direction of the frame element (a direction perpendicular to the plate thickness direction) at a key point of the frame element, A lead frame manufacturing method has been proposed in which the distance between predetermined frame elements is shortened by crushing the deformed portions of the semi-processed product. In the case of obtaining a lead frame in which the distance between the component mounting portion and the lead terminal portion is shortened by the method disclosed in Patent Document 2, for example, as shown in FIG. As shown in FIG. 13B, a semi-finished product of a lead frame in which deformed portions L11 and L21 curved in the width direction are formed in frame elements L1 and L2 provided on both sides of the lead terminal portion Lb by punching, respectively. Further, the distance between the component mounting portion La and the lead terminal portion Lb is shortened by crushing the deforming portions L11 and L21.
Japanese Patent Laid-Open No. 10-261755 JP-A-4-313263

  In the lead frame described in Patent Document 1, the distance between the component mounting portion and the lead terminal portion itself is not shortened, but a protrusion is formed at each adjacent end portion, so that they are adjacent to each other. Since the distance between the end portions is only shortened, as shown in FIG. 12 (B), at least a part of the chip is placed on the thin projection La1 formed at the end portion of the component mounting portion. If it is not attached, the effect of shortening the length of the wire W cannot be obtained.

  However, in the case of such a configuration, the thickness of the portion on which the chip T is placed becomes thin, so that heat is dissipated from the chip and the temperature of the chip rises. Therefore, the lead frame obtained by the method disclosed in Patent Document 1 is not suitable for a semiconductor element chip having a large energization current.

  In addition, in the lead frame described in Patent Document 1, the flatness of the component mounting surface of the component mounting portion La is impaired when the protrusions La1 and Lb1 are formed by crushing a predetermined portion of the semifinished product of the lead frame with a punch. There is a risk of being. If the flatness of the component mounting surface is damaged and the component mounting surface can be inclined, solder or adhesive may flow when the chip is mounted on the component mounting portion by the die bonder, which hinders chip mounting. There was a risk of coming.

  Furthermore, in the lead frame described in Patent Document 1, since it is necessary to mount a chip on the protrusion La1, there is a problem that the surface of the lead frame that can be used for mounting components is limited to the front side.

  In the case of the method described in Patent Document 2, as shown in FIG. 13, it is necessary to form the deformed portions L11 and L21 that can be easily crushed when punching a semi-finished lead frame product. There is a deformed part that can be easily crushed, but the width dimension of the deformed part must be sufficiently smaller than the width dimension of the frame element. It is not easy to form by punching. In particular, when the thickness of the frame material is thick, it is difficult to form a deformed portion having a width dimension smaller than that of the frame element by punching a part of the frame element.

  In addition, when the deformed portions L11 and L21 curved in the width direction of the frame element are provided, it is inevitable that the cross-sectional area of the frame elements L1 and L2 is reduced at these deformed portions. When the frame elements L1 and L2 are used as the energization paths, the resistance value of the energization paths becomes high, which is not preferable.

  Furthermore, according to the method described in Patent Document 2, when the deformed portions L21 and L22 are crushed, there is a risk that the portions on both sides of each deformed portion may be inclined, so that the component mounting portion La and the lead terminal portion Lb There is also a problem that it is difficult to form a uniform gap between the two by moving them linearly.

  The object of the present invention is to provide a component mounting portion without changing the thickness of a part of the frame element used as the component mounting portion, making it difficult to punch the lead frame, or increasing the resistance value of the frame element. Provided is a lead frame capable of shortening the distance between a frame element used and an adjacent frame element to which a wire connected to a component attached to the frame element is crossed, and a method of manufacturing the lead frame. There is.

  The present invention is directed to a lead frame in which a plurality of frame elements including a component mounting portion are arranged in a predetermined pattern. In the present invention, a component mounting portion and a component attached to the component mounting portion ( Usually, the wiring wire connected to the component attached to the component mounting portion so as to shorten the distance between the adjacent frame elements to which the wiring wire connected to the chip-shaped component) is connected. A part of a specific frame element selected from among the plurality of frame elements is deformed in a mountain shape in the plate thickness direction so as to reduce the gap between the two.

  If comprised as mentioned above, when assembling an electronic component, when assembling an electronic component, the distance between the adjacent frame element used as the destination of the wire for wiring connected to the component attached to this component attachment part is shortened. Therefore, the length of the wire can be shortened. Accordingly, the amount of wire used in the wire bonding process when assembling the electronic component can be reduced, and the cost can be reduced.

  Further, when the distance between the component mounting portion and the adjacent frame element is shortened as described above, it is possible to reduce the size of the package made of the mold resin provided so as to cover the main part of the lead frame together with the chip. Therefore, not only can the electronic parts be reduced in size and weight, but also the amount of resin used can be reduced to reduce the cost.

  Furthermore, when configured as described above, when the flowability of the resin is different between the front side and the backside of the lead frame, the flowability of the resin is improved, and the resin is satisfactorily filled into each part in the package molding die. Therefore, it is possible to prevent the appearance of the package from being deteriorated.

  In addition, since the distance between the component mounting portion and the adjacent frame element can be reduced without changing the thickness of a part of the lead frame, the above configuration can be applied to a chip with a large amount of heat generation. can do.

  Further, as described above, a part of a specific frame element is deformed into a mountain shape in the plate thickness direction, so that the adjacent frame serving as a crossover of the wire connected to the component attachment portion and the component attached to the component attachment portion. If the distance between the elements is shortened, it is not necessary to process the component mounting surface, and therefore, the flatness of the component mounting surface is impaired and the possibility of hindering the mounting of the component can be eliminated.

  In addition, when configured as described above, the length of the wire can be shortened, the heat dissipation performance from the chip can be prevented from being lowered, even when the chip is attached to either the front or back side of the lead frame component mounting part. An effect of reducing the size can be obtained. Therefore, both the front and back surfaces of the lead frame can be used for mounting components, and the effect that the surface of the lead frame that can be used is not restricted is obtained.

  In addition, as described above, a part of the frame element is deformed into a chevron by pressing in the plate thickness direction, and adjacent to the connecting portion of the component attachment portion and the wire connected to the component attached to the component attachment portion. If the distance between the frame element is shortened, a portion having a small cross-sectional area is not formed in the middle of the frame element, and the resistance value of the frame element does not increase.

  Further, when configured as described above, since it is not necessary to provide a deformed portion curved in the width direction in a part of the frame element, it is possible to easily punch the lead frame.

  In addition, as described above, a part of a specific frame element is deformed into a mountain shape in the thickness direction, so that the frame element used as the component mounting portion and the adjacent frame element are relatively moved to reduce the distance between the two. Then, when part of a specific frame element is deformed into a chevron shape, it is adjacent to the frame element used as a component mounting part simply by applying a flat mold to both sides of the lead frame and regulating both sides. The frame element can be easily linearly moved to form a uniform gap between them.

  The present invention provides a lead in which a plurality of frame elements including a component mounting portion are formed by punching a frame material made of a conductive plate having a thick portion and a thin portion, and the component mounting portion is formed of a thick portion. It can also be applied to frames. In this case, among the plurality of frame elements so as to shorten the distance between the component mounting portion and the adjacent frame element to which the wire connected to the component mounted on the component mounting portion is crossed, A part of the portion formed by the thin portion is deformed into a mountain shape in the plate thickness direction.

  According to the present invention, there is also provided a method of manufacturing a lead frame in which a plurality of frame elements including a component mounting portion are arranged in a predetermined pattern. In the manufacturing method according to the present invention, after forming a semi-processed product of a lead frame having a plurality of frame elements including a component mounting part by punching a frame material made of a conductive plate, the component mounting part of the semi-processed product and the The specific frame element selected from the multiple frame elements of the semi-finished product so as to reduce the distance between adjacent frame elements to which the wire connected to the part attached to the part attachment part is routed. A process is performed in which a part is pressed in the thickness direction and deformed into a chevron.

  In a preferred embodiment of the manufacturing method according to the present invention, a half of a lead frame having a plurality of frame elements including a frame element for component mounting portion configuration that forms a component mounting portion by punching a frame material made of a conductive plate. A first punching step for forming a processed product, and a chevron projecting to one side in the plate thickness direction of the component mounting portion constituting frame element by drawing the semi-finished component mounting portion constituting frame element The drawing step for forming the projecting portion and the bottom portion of the projecting portion are punched to form a gap, and the component mounting portion constituting frame element is divided into the first portion and the second portion facing each other through the gap. A distance between the first part and the second part by performing a flat pressing process so as to eliminate the projecting portion across the first part and the second part. The short And a flat pushing process in which a flat surface suitable for holding a part is formed on the first part and the second part, and at least one of the first part and the second part is used as a part mounting part. And do.

  As described above, the flat parts suitable for holding the parts are formed by drawing and punching the frame elements for component mounting parts provided on the semi-finished product of the lead frame, followed by flat pressing. By doing so, it is possible to reduce the gap across which the wiring wires are routed without performing a pressing process in which a specific frame element of the lead frame is bent in a chevron shape in the thickness direction, so that the vertical and horizontal dimensions of the lead frame are changed. In this way, it is possible to obtain a lead frame in which the gap for passing the wiring wire is reduced, and by performing the process for reducing the gap for passing the wire, the lead frame complementary dimension accuracy is deteriorated. Can be prevented.

  In the above method, the lead frame semi-processed product is punched, and then the drawing process and the punching process are performed to form the reduced gap. It is also possible to form a lead frame by punching the frame material after forming a reduced gap at a critical point. In this case, a drawing step of drawing a specific portion of the frame material made of a conductive plate to form a chevron-like protruding portion protruding on one side of the frame material in the plate thickness direction, and the specific portion The first punching step of forming a gap by punching the bottom of the protruding portion formed on the surface, and the width of the gap is reduced by flat pressing the portion where the protruding portion is formed so as to eliminate the protruding portion. In addition, a flat pressing process for forming a flat surface suitable for holding a component around the gap, and one and the other of the portions where the flat surfaces on both sides of the narrowed gap are formed are part mounting frames. A frame material is punched out to form an element and an adjacent frame element, and a second punching process for forming a plurality of frame elements is performed.

  As described above, according to the present invention, it is possible to shorten the distance between the component attachment portion and the adjacent frame element that is the destination of the wiring wire connected to the component attached to the component attachment portion. Therefore, it is possible to reduce costs by reducing the amount of wires used for wiring.

  Further, according to the present invention, since the distance between the component mounting portion and the adjacent frame element can be shortened, the package provided so as to cover the chip can be reduced in size, and the electronic component can be reduced in size and weight. In addition to reducing the amount of resin used, the cost can be reduced.

  Further, according to the present invention, since the gap between the frame elements can be reduced, the flowability of the resin on the front side and the back side of the lead frame is improved when forming a package made of mold resin, and the frame The resin can be satisfactorily filled into the gaps between the elements.

  Further, according to the present invention, since the gap between the wires can be reduced without reducing the thickness of a part of the component mounting portion to which the chip is attached, the heat dissipation performance from the chip is reduced. Can be prevented.

  Further, in the present invention, a part of a specific frame element is deformed into a mountain shape in the plate thickness direction, and an adjacent frame element serving as a crossover of a wire connected to a part attached to the part attachment part. When the distance between the two is shortened, there is no need to process the component mounting surface, so that the flatness of the component mounting surface is impaired and the possibility of hindering component mounting can be eliminated. .

  In addition, according to the present invention, when a chip is mounted on any surface of the lead frame component mounting portion, the length of the wire can be shortened, the heat dissipation performance from the chip can be prevented from being reduced, and the package can be downsized. Therefore, it is possible to use both the front and back surfaces of the lead frame for mounting components, and there is an advantage that the surface of the lead frame that can be used is not restricted.

  Further, in the present invention, a part of the frame element is pressed in the plate thickness direction so as to be deformed into a chevron and adjacent to the connection point between the component attachment portion and the wire attached to the component attachment portion. When the distance between the frame element and the frame element is shortened, the frame element used as the component mounting part is crushed by the deformed part curved in the width direction of the frame element and the adjacent frame element. As in the case of the prior art that shortens the distance, there is no need to provide a deformed portion with a small cross-sectional area in the middle of the frame element, which makes it difficult to punch the lead frame or increase the resistance value of the frame element. The distance between the frame element used as the component mounting portion and the adjacent frame element can be shortened.

  Further, in the present invention, the distance between the component attachment portion and the adjacent frame element to which the wire connected to the component attached to the component attachment portion is subjected to drawing processing, punching processing, and flat pressing processing. When the length of the lead frame is shortened, the gap between the wiring wires can be reduced without performing a pressing process in which a specific frame element of the lead frame is bent in a mountain shape in the plate thickness direction. Without changing the vertical and horizontal dimensions, it is possible to obtain a lead frame with a reduced gap for passing the wiring wire, and by processing to reduce the gap that allows the wire to pass, the lead frame complementary dimension accuracy Can be prevented.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. 1 to 3 show the steps of manufacturing a lead frame in the first embodiment of the present invention step by step. 1A is a front view showing a first semi-finished product of a lead frame, and FIGS. 1B and 1C are cross-sectional views taken along lines B1-B1 and C1-C1 of FIG. 1A, respectively. The figure is shown. 2A is a front view showing a second semi-finished product of the lead frame, and FIGS. 2B and 2C are a cross-sectional view taken along line B2-B2 and a line C2-C2 in FIG. It is sectional drawing. 3A shows a front view of the completed lead frame, and FIGS. 3B and 3C show a cross-sectional view taken along line B3-B3 and a cross-sectional view taken along line C3-C3 in FIG. 3A, respectively. ing.

  In the present embodiment, first, a frame material made of a conductive plate having a uniform thickness is punched to obtain a first half-processed product 1 ″ of a lead frame as shown in FIGS. 1 (A) to (C). In these drawings, the plate thickness of the lead frame is exaggerated to be larger than the actual thickness.

  In FIG. 1, 1A and 1B are strip-shaped first and second transverse bone portions extending in parallel with each other, and 1C and 1D are parallel to each other between the first transverse bone portion 1A and the second transverse bone portion 1B. The first and second longitudinal bone portions 1E extending in the direction of the belt are provided so as to connect the first and second transverse bone portions 1A and 1B between the first and second longitudinal bone portions 1C and 1D. This is a plate-like middle bone portion, and the middle bone portion 1E is composed of a wide portion 1E1 and a narrow portion 1E2.

  As shown in FIGS. 2A to 2C, after forming the first semi-processed product 1 ″ shown in FIG. 1, the wide portion 1E1 of the middle bone portion 1E is punched to form a gap G. The wide portion 1E1 is divided into a first wide portion 1E11 and a second wide portion 1E12 to form a second half-finished product 1 'of the lead frame.

  Next, in a state where flat surfaces are applied to both the front and back surfaces of the second semi-processed product 1 ′ and both surfaces thereof are regulated, a part of the longitudinal bone portions 1C and 1D of the second semi-processed product 1 ′ is pressed. Then, by bending a part of these longitudinal bones into a chevron in the thickness direction, as shown in FIGS. 3 (A) to (C), a part of each of the longitudinal bones 1C and 1D Mountain-shaped deformed portions 1C1 and 1D1 projecting with the same projecting length h are formed on the same side in the plate thickness direction. As a result, the first wide portion 1E11 and the second wide portion 1E11 and the second wide portion 1E12 are linearly moved in the directions approaching each other to form a reduced gap g between the first wide portion 1E11 and the second wide portion 1E12. The distance from 1E12 is reduced from D shown in FIG. 2 to d shown in FIG. 3 to complete the lead frame 1 according to the present invention.

  In the present embodiment, the lateral bone portions 1A and 1B, the longitudinal bone portions 1C and 1D, the component mounting portion 1a, the first wide portion 1E11 and the second wide portion 1E12 and the narrow portion 1E2 of the middle bone portion. Each constitutes a frame element of the lead frame 1, and the plurality of frame elements are arranged in a predetermined pattern with a gap between each other. In the present embodiment, a frame element including the first wide portion 1E11 of the middle bone portion is used as the component mounting portion 101, and a frame element including the second wide portion 1E12 and the narrow portion 1E2 is used as the component mounting portion 101. It is used as an adjacent frame element (in this example, a lead terminal portion) 102 that serves as a destination of a wiring wire connected to a component (chip) to be attached.

  An electronic component configured using the lead frame 1 shown in FIG. 3 is shown in FIG. FIG. 4A is a front view showing a part of the cross section, and FIGS. 4B and 4C are a cross-sectional view taken along the line B4-B4 and a cross-sectional view taken along the line C4-C4 in FIG. The chip 3 is attached to the component attachment portion 101 by a die bonder, and the wiring wire 4 connects the electrode of the chip 3 and the frame element 102 constituting the lead terminal portion. Further, a mold is formed so as to cover most of the vertical bone portion 1C and the horizontal bone portion 1A, and the part mounting portion 101 and the portion including the wide portion and the narrow portion of the frame element 102 together with the chip 3 and the wire 4. A package 5 made of resin is formed. In this embodiment, the package 5 is formed such that the top of the mountain-shaped deformed portion 1C1 is exposed to the outside, and the top of the deformed portion 1C1 exposed from the package (see FIG. 4C) is used as an electrode. Yes.

  If comprised as mentioned above, the distance between the component attachment part 101 and the adjacent frame element 102 used as the destination of the wiring wire 4 connected to the chip | tip attached to this component attachment part can be shortened. Therefore, it is possible to reduce the cost of the electronic component by reducing the amount of wire used when assembling the electronic component.

  Further, since the distance between the component mounting portion 101 and the adjacent frame element 102 is shortened when configured as described above, the package made of mold resin provided to cover the chip together with a part of the lead frame can be downsized. As a result, the electronic component can be reduced in size and weight. In addition, the amount of resin used when forming the package can be reduced to reduce the cost.

  Further, since the distance between the component mounting portion 101 and the adjacent frame element 102 can be shortened without changing the thickness of the lead frame, the thickness of the frame where the chip is placed can be reduced. It becomes thin, and it can prevent that the thermal radiation performance from a chip | tip deteriorates. Therefore, the lead frame according to the present invention can be applied to a chip having a large amount of heat generation without any problem.

  Further, when configured as described above, when the distance between the component mounting portion 101 and the adjacent frame element 102 to which the wire connected to the component mounted on the component mounting portion is shortened, the component mounting surface is reduced. Therefore, it is possible to eliminate the possibility that the flatness of the component mounting surface is impaired and the chip mounting is hindered.

  Moreover, since the actual distance between the component mounting part 101 of the lead frame and the adjacent frame element 102 is shortened when configured as described above, when a chip is mounted on any surface of the component mounting part of the lead frame In addition, it is possible to obtain an effect of shortening the length of the wiring wire or reducing the size of the package. Therefore, both the front and back surfaces of the lead frame can be used for mounting the component, and the surface used for mounting the component is not limited to one side.

  Further, as described above, when the distance between adjacent frame elements can be shortened, the flowability of the resin on the front side and the back side of the lead frame 1 is improved when the package is formed, and the package is formed. Since the resin can be satisfactorily filled into each part in the mold, it is possible to prevent the appearance of the package from being deteriorated.

  FIG. 11 schematically shows a process of injection molding a package and an electronic component completed by molding the package when the gap between the component mounting portion of the lead frame and the adjacent frame element is wide. is there. FIG. 11A shows a state in which the lead frame to which the chip is attached is inserted into the package molding die, and FIGS. 11B to 11D show the inside of the molding die when the package 5 is molded. Shows how the resin flows in FIG. 11E shows an electronic component completed by molding a package.

  11A to 11D, reference numerals 11 and 12 respectively denote an upper mold and a lower mold for molding, and 13 denotes a gate of the mold. In this example, since the chip 3 is present on the surface side of the lead frame 1, the distance between the surface of the lead frame 1 and the inner surface of the upper die 11 is the distance between the back surface of the lead frame 1 and the inner surface of the lower die 12. It is wider than the interval between them. Therefore, the resin is less likely to flow on the back side than the front side of the lead frame 1, and the resin 15 injected from the gate 13 into the mold is as shown in FIGS. 11 (B) to 11 (D). The back side of the lead frame flows later than the front side. Since the resin flowing on the surface side of the lead frame has a high flow velocity, most of the resin flows through the gap G between the component mounting portion 101 and the adjacent frame element 102. In contrast, since the flow rate of the resin flowing on the back side of the lead frame is lower than the flow rate of the resin flowing on the front side, the resin flowing on the back side of the lead frame flows toward the endmost part in the mold. On the way, it flows a lot into the gap G between the component mounting portion 101 and the frame element 102. Therefore, if the gap G between the component mounting portion 101 and the frame element 102 is wide, the resin 15 flowing on the back side of the lead frame is often used to fill the gap G, and the resin reaches the end of the mold. May not be reachable. When such a state occurs, as shown in FIG. 11E, on the back side of the lead frame, a defective portion 5a in which the resin is insufficient is generated in a part of the package 5, and the appearance of the package is deteriorated. The protection function of the package may be impaired.

  On the other hand, FIG. 10 schematically shows a process of injection molding a package and an electronic component completed by molding the package when the width of the gap between the component mounting portion of the lead frame and the adjacent frame element is narrowed. It is shown in. 10A shows a state in which the lead frame to which the chip is attached is inserted into the package molding die, and FIGS. 10B to 10D show the inside of the molding die when the package 5 is molded. Shows how the resin flows in FIG. 10E shows an electronic component completed by molding a package.

  When the gap g between the component mounting portion of the lead frame and the adjacent frame element is narrowed as in the present invention, the back surface of the lead frame 1 is shown in FIGS. 10 (C) and 10 (D). Since the resin 15 flowing on the side does not easily enter the gap g, the resin used to fill the gap g out of the resin flowing on the back side of the lead frame 1 is reduced, so that the resin can be used on both the front side and the back side of the lead frame. The resin injected into the mold can reach the extreme end. Therefore, it is possible to prevent a portion where the resin is insufficient from being formed in a part of the package 5, and it is possible to prevent the appearance of the package from being deteriorated and the protection function thereof from being impaired.

  Further, in the present invention, a part of a specific frame element of the lead frame is deformed into a mountain shape in the plate thickness direction to form a deformed portion so that a distance between a predetermined component mounting portion and an adjacent frame element is increased. For shortening, as shown in FIG. 13, the deformed portions L11 and L21 having a narrow width curved in the width direction of the frame element are provided, and the deformed portions are crushed so that the part mounting portion is adjacent to the adjacent frame element. It is possible to solve various problems that occur when the method of shortening the distance is taken.

  As described above, in the present invention, a plurality of components are attached so as to shorten the distance between the component attachment portion and the adjacent frame element to which the wire connected to the component attached to the component attachment portion is crossed. A part of a specific frame element selected from the frame elements is deformed into a mountain shape in the thickness direction. Therefore, the arrangement pattern of the frame elements of the lead frame is set so that any one of the frame elements can be selected as a specific frame element to be deformed.

  In the above embodiment, the lead frame is formed by punching a frame material made of a conductive plate having a uniform thickness. However, the thickness of the frame element used as the component mounting portion is increased to dissipate heat from the chip. In order to improve the performance, the present invention can also be applied to the case where a lead frame is formed by punching a frame material made of a conductive plate having a thick portion in part.

  FIG. 5 shows a second embodiment of the present invention in which a component attachment portion is formed by a thick portion by punching out a frame material having a thick portion and a thin portion, and FIG. ) Is a front view of the lead frame semi-finished product 1 ′ formed by punching in this embodiment, FIG. 5B is a cross-sectional view taken along line B 5 -B 5 of FIG. 4A, and FIG. It is sectional drawing of the C5 part and C5 'part of (A).

  In this example, the lead frame blank 1 'includes first and second transverse bone portions 1a and 1b extending in parallel to each other, and first and second longitudinal bone portions extending between the transverse bone portions. 1c and 1d, and a first island portion 1g between the first and second longitudinal bone portions 1c and 1d and connected to the first transverse bone portion 1a via crank-shaped connecting portions 1e and 1f, Similarly, it is composed of a second island portion 1i between the first and second longitudinal bone portions 1c and 1d and connected to the second transverse bone portion 1b via a strip-like connecting portion 1h. A gap G extending in a direction inclined by 45 ° with respect to the longitudinal direction of the longitudinal bone portions 1c and 1d is formed between the first island portion 1g and the second island portion 1i. The first island portion 1g and the second island portion 1i and the portions 1c1 and 1d1 corresponding to the island portions 1g and 1i of the first and second longitudinal bone portions 1c and 1d are thick in the conductive plate (frame material). It is formed by the part. The width dimension of the gap G (distance between the island portions 1g and 1i) D (see FIG. 7A) is substantially equal to the thickness of the thick portion of the conductive plate constituting the lead frame.

  The connecting portion 1e connecting the first island portion 1g to the transverse bone portion 1a includes a bending portion 1e1 extending in parallel with the transverse bone portion 1a, and a longitudinal bone portion 1c of the island portion 1g at one end of the bending portion. It consists of a non-bending portion 1e2 provided so as to be connected to the end portion on the side, and a non-bending portion 1e3 provided so as to connect the other end of the bending portion 1e1 to the transverse bone portion 1a. The connecting portion 1f connecting the second island portion 1g to the transverse bone portion 1a includes a bending portion 1f1 extending in parallel with the transverse bone portion 1a, and one end of the bending portion as the longitudinal bone portion of the island portion 1g. It consists of a non-bending portion 1f2 provided so as to be connected to the end portion on the 1d side, and a non-bending portion 1f3 provided so as to connect the other end of the bending portion 1f1 to the transverse bone portion 1a. . At the stage where the conductive plate (lead frame material) is punched to form the semi-processed product 1 'shown in FIG. 5, as shown in FIG. 5C, the bent portions 1e1 and 1f of the connecting portions 1e and 1f and 1f1 is formed in a flat plate shape.

  After the lead frame semi-finished product shown in FIG. 5 is formed, the bent portions 1e1 and 1f1 of the connecting portions 1e and 1f are bent in a mountain shape in the respective plate thickness directions, as shown in FIG. 6B. Are formed with bent portions 1e4 and 1f4. As a result, as shown in FIG. 7B, the island portion 1g is moved to the island portion 1i side so that the gap between the two island portions 1g and 1i is shortened, and the island portions 1g and 1i The lead frame 1 is completed by shortening the distance between D shown in FIG. 7A to d shown in FIG. 7B.

  Next, as shown in FIG. 6A, the chip 3 is attached to the island part 1g of the lead frame 1, and the wire 4 connected to the electrode part of the chip 3 is connected to the island part 1i across the gap g. Thereafter, most of the horizontal bone portion 1a of the lead frame 1, most of the vertical bone portion 1c, island portions 1g and 1i, connecting portions 1e and 1f, and almost half of the connecting portion 1h are connected to the chip 3 and the wire. A package 5 made of a mold resin is formed by injection molding so as to be coated together with 4, and an unnecessary part of the lead frame is cut off to complete an electronic component.

  In FIG. 6A, a broken line 1g ′ indicates the position of the island portion 1g before the bending portions of the connecting portions 1e and 1f are bent.

  In the second embodiment shown in FIG. 5 to FIG. 7, the lead frame includes the horizontal bone portions 1a and 1b, the vertical bone portions 1c and 1d, the connecting portions 1e and 1f, the island portions 1g and 1i, and the connecting portion 1h as frame elements. Of these frame elements, the island portion 1g is used as a component mounting portion. Further, the connecting portion 1h and the end portion of the longitudinal bone portion 1c on the lateral bone portion 1b side are used as lead terminal portions.

  As described above, the present invention can also be applied to a case where a plurality of frame elements including a component mounting portion and a lead terminal portion are formed by punching out a conductive plate having a thick portion and a thin portion. In this case, in order to facilitate bending, the portion to be bent is formed by a thin portion of the conductive plate.

  In each of the above embodiments, after a lead frame material made of a conductive plate is punched to form a lead frame semi-processed product, a part of a specific frame element selected from a plurality of frame elements is arranged in the plate thickness direction. By changing the shape to a chevron, the distance between the component mounting portion and the adjacent frame element that is the destination of the wire connected to the component mounted on the component mounting portion is shortened. By performing drawing processing, punching processing and flat pressing processing on the lead frame, it is possible to obtain a lead frame in which the gap between the frame elements is shortened.

  FIGS. 8A to 8D sequentially show the process of forming a lead frame in the third embodiment of the present invention in which a lead frame is manufactured by subjecting the lead frame material to drawing, punching, and flat pressing. It is shown. FIG. 8E shows a cross-sectional view of an electronic component assembled using the lead frame obtained by this method. In the case of this method, a lead frame semi-finished product having a plurality of frame elements including the component attachment portion constituting frame element 21 which will constitute the component attachment portion by first punching out a frame material made of a conductive plate. A first punching step for forming 22 is performed. The semi-processed product 22 is provided with a plurality of other frame elements in addition to the component mounting portion constituting frame elements, but the illustration of these other frame elements is omitted. In this case, the front view of the semi-processed product 22 is the same as that shown in FIG. 1A, for example, and the component attachment portion constituting frame element 21 is formed similarly to the wide portion 1E shown in FIG. .

  After the lead frame semi-processed product 22 is formed, the component mounting portion constituting frame element 21 of the semi-processed product 22 is subjected to a drawing process, and the component mounting portion constituting frame element projects to one side in the plate thickness direction. A squeezing step is performed to form the chevron-shaped protrusion 21A (see FIG. 8B).

  Thereafter, as shown in FIG. 8C, a gap G is formed by punching out the bottom of the projecting portion 21A, and the first portion 21a and the second portion which are opposed to each other through the gap G are formed with the component mounting portion constituting frame elements. A second punching step is performed to divide the portion 21b.

  After performing the second punching step, flat push so as to eliminate the protruding portion 21A across the first portion 21a and the second portion 21b (to restore the shape of the portion where the protruding portion is formed) By performing the processing, as shown in FIG. 8D, the distance between the first portion 21a and the second portion 21b is shortened, and parts are added to the first portion 21a and the second portion 21b. The flat surfaces 21a1 and 21b1 suitable for holding are formed, and a flat pressing process is performed in which at least one of the first portion 21a and the second portion is a component mounting portion. As a result, the lead frame 23 in which the distance between the frame element (first portion 21a) used as the component mounting portion and the adjacent frame element (second portion 21b) is reduced is obtained.

  When assembling an electronic component using this lead frame, for example, as shown in FIG. 8 (E), the first portion 21a is used as a component mounting portion, and the chip 3 is mounted on the component mounting portion. After connecting the second part 21b with the wire 4, the package 5 made of mold resin is formed to complete the electronic component.

  As described above, a flat portion suitable for holding a component by subjecting the component mounting portion constituting frame element 21 provided on the lead frame semi-finished product 22 to drawing and punching and then flat pressing. If the surfaces 21a1 and 21b1 are formed, the gap that allows the wiring wires to cross can be reduced without performing a pressing process in which a specific frame element of the lead frame is bent in a mountain shape in the plate thickness direction. Without changing the vertical and horizontal dimensions of the lead frame, it is possible to obtain a lead frame with a reduced gap for passing the wiring wires. Therefore, it is possible to perform a process of reducing the gap where the wire is passed without deteriorating the complementary dimension accuracy of the lead frame.

  In the embodiment shown in FIG. 8, the lead frame semi-processed product 22 is punched and then the drawing, punching, and flat pressing are performed to form a reduced gap. A lead frame can be obtained by punching and flat-pressing to form a reduced gap at a point of the frame material and then punching the frame material.

  In this case, a drawing process is performed in which a specific portion of the frame material made of a conductive plate is drawn to form a chevron-shaped protruding portion protruding on one side of the frame material in the plate thickness direction (see FIG. 8B). Corresponding step), a first punching step (step corresponding to FIG. 8C) for forming a gap by punching the bottom of the chevron-shaped protruding portion formed in the specific portion, and the protruding portion so as to eliminate the protruding portion. A flat pressing step (step corresponding to FIG. 8D) for forming a flat surface suitable for holding a part around the gap, while narrowing the width of the gap by applying flat pressing to the formed portion; A plurality of frame elements are formed by punching the frame material so that one and the other of the portions where the flat surfaces on both sides of the narrowed gap are formed are a component mounting frame element and an adjacent frame element, respectively. Performing a second punching step (step corresponding to FIG. 8A) to form a lead frame.

  In each of the above embodiments, a lead frame in which frame elements are arranged in a simple pattern is taken as an example. However, as shown in FIG. 9, a lead frame 30 in which a number of frame elements are arranged in a more complicated pattern is used. The present invention can also be applied. The lead frame 30 shown in FIG. 9 includes a frame portion 31 formed in a rectangular shape by short side portions 31A and 31B and long side portions 31C and 31D, and two short side portions 31A and 31B of the frame portion 31, respectively. Lead terminal portions a1 to a4 and a5 to a8 provided so as to protrude, and lead terminal portions b1 to b6 and b7 to b12 provided so as to protrude from the two long side portions 31C and 31D of the frame portion 31, respectively. And component attachment portions c1 to c3 connected to the long side portion 31C of the frame portion 31 via the connection portion, and component attachment portions c4 connected to the other long side portion 31D of the frame portion 31 via the connection portion. Or c6.

  In the lead frame having the pattern as shown in FIG. 9, the lead terminal portions a1 to a4 and the component mounting portions c1 and c4 are formed by deforming the portions indicated by the symbols Y1 and Y1 'into a mountain shape in the plate thickness direction. The gap G1 can be shortened, and the portions indicated by reference characters Y2 and Y2 'are deformed in a mountain shape in the plate thickness direction, so that the component mounting portions c1 and c5 and the component mounting portions c4 and c5 Can be shortened. Further, by deforming the portions indicated by reference characters Y3 and Y3 'into a chevron shape in the thickness direction, the gap G3 between the component mounting portions c2 and c3 and between the component mounting portions c5 and c6 can be shortened. . Further, by deforming the portions indicated by reference characters Y4 and Y4 'in a chevron shape in the thickness direction, the gap G4 between the lead terminal portions a5 to a8 and the component mounting portions c3 and c6 can be shortened. , X1 ′, the gap G5 between the component mounting portions c1 to c3 and c4 to c6 can be shortened by deforming the portion indicated by X1 ′ into a mountain shape in the plate thickness direction.

(A) is the front view which showed the 1st semi-processed product of the lead frame used in the 1st Embodiment of this invention, (B) and (C) are the B1-B1 sectional view taken on the line of (A), and C1, respectively. FIG. (A) is the front view which showed the 2nd semi-finished product of the lead frame used in the 1st Embodiment of this invention, (B) and (C) are the B2-B2 sectional view taken on the line of (A), and C2, respectively. FIG. (A) is the front view which showed the completed product of the lead frame formed in the 1st Embodiment of this invention, (B) and (C) are the B3-B3 sectional view taken on the line of (A), and C3-C3, respectively. It is line sectional drawing. (A) is the front view which showed an example of the electronic component comprised using the lead frame of the 1st Embodiment of this invention, (B) and (C) are the B4-B4 sectional view taken on the line of (A), respectively. It is a C4-C4 line sectional view. The front view which showed the semi-finished product of the lead frame formed in the 2nd Embodiment of this invention, (B) is the B5-B5 sectional view taken on the line of (A), (C) is C5 part and C5 of (A) It is sectional drawing of a part. FIG. 5B is a cross-sectional view of an example of an electronic component configured using the lead frame according to the second embodiment of the present invention, and FIG. 5B is a cross-sectional view of the C6 and C6 ′ portions of FIG. . (A) And (B) is explanatory drawing for demonstrating the process of shortening the distance between frame elements in the 2nd Embodiment of this invention. It is sectional drawing which showed the process in which the lead frame is formed in the 3rd Embodiment of this invention later on. It is the front view which showed the semi-finished product of the lead frame of the 4th Embodiment of this invention. (A) thru | or (D) is sectional drawing explaining the flow of the resin at the time of forming the package which consists of mold resin using the lead frame concerning this invention, (E) is comprised using the lead frame concerning this invention. It is sectional drawing of the manufactured electronic component. (A) thru | or (D) is sectional drawing explaining the flow of the resin at the time of forming the package which consists of mold resin using the conventional lead frame, (E) is the electronic component comprised using the conventional lead frame It is sectional drawing. (A) is sectional drawing which showed typically the structure of the principal part of the electronic component using the conventional lead frame in which the process for shortening the distance between frame elements was not given, (B) is adjacent. It is sectional drawing which showed typically the structure of the principal part of the electronic component using the conventional lead frame which shortened the distance between adjacent frame elements by forming a protrusion in the adjacent edge part of a frame element. (A) is the front view which showed the semi-processed product of the conventional lead frame which formed the deformation | transformation part curved in the width direction in the frame element provided in the both sides of a component attachment part and a lead terminal part, (B) is (A). It is the front view which showed the state which shortened the distance between a component attachment part and a lead terminal part by crushing the deformation | transformation part shown by (3).

Explanation of symbols

1 ", 1 'lead frame semi-finished product
1 Lead frame 101 Component mounting portion 102 Lead terminal portion 1g Component mounting portion 1i Component mounting portion
3 chips
4 wires

Claims (5)

In a lead frame in which a plurality of frame elements including a component mounting portion are arranged in a predetermined pattern,
The plurality of frame elements are selected from among the plurality of frame elements so as to shorten a distance between the component attachment portion and an adjacent frame element to which a wire connected to a component attached to the component attachment portion is passed. A lead frame characterized in that a part of a specific frame element is deformed into a mountain shape in the thickness direction. A plurality of frame elements including a component attachment portion are formed by punching a frame material made of a conductive plate having a thick portion and a thin portion, and the component attachment portion is a lead frame formed by the thick portion.
Among the plurality of frame elements, the thin-walled portion is used to shorten the distance between the component mounting portion and an adjacent frame element to which a wire connected to the component mounted on the component mounting portion is connected. A lead frame, wherein a part of the portion formed by the step is deformed into a mountain shape in the thickness direction. In a method of manufacturing a lead frame in which a plurality of frame elements including a component mounting portion are arranged in a predetermined pattern,
After forming a semi-processed product of a lead frame having a plurality of frame elements including the component mounting portion by punching a frame material made of a conductive plate, the component mounting portion of the semi-processed product and a component attached to the component mounting portion A part of the specific frame element selected from the plurality of frame elements of the semi-finished product is reduced in the thickness direction so as to shorten the distance between adjacent frame elements to which wires connected to the A method of manufacturing a lead frame, comprising performing a step of deforming into a chevron by pressing. In a method of manufacturing a lead frame in which a plurality of frame elements including a component mounting portion are arranged in a predetermined pattern,
A first punching step of forming a semi-finished product of a lead frame having a plurality of frame elements including a frame element for constituting a part mounting part that constitutes the part mounting part by punching a frame material made of a conductive plate When,
A drawing step of drawing the half-finished component mounting portion constituting frame element to form a chevron-like projecting portion projecting on one side in the thickness direction of the component mounting portion constituting frame element;
A second punching step in which a gap is formed by punching out the bottom of the protruding portion, and the component mounting portion constituting frame element is divided into a first portion and a second portion facing each other through the gap;
The flat pressing process is performed so as to eliminate the protruding portion across the first portion and the second portion, thereby reducing the distance between the first portion and the second portion and the first portion. A flat pushing process in which a flat surface suitable for holding a part is formed on the part and the second part, and at least one of the first part and the second part is used as the part attaching part;
A method for manufacturing a lead frame. Manufacture a lead frame having a plurality of frame elements including a component mounting frame element used for mounting a component and an adjacent frame element to which a wire connected to the component mounted on the component mounting frame element is passed. In the way to
A drawing process in which a specific portion of the frame material made of a conductive plate is drawn to form a mountain-shaped protruding portion protruding on one side of the frame material in the thickness direction of the frame material;
A first punching step of forming a gap by punching a bottom portion of the protruding portion formed in the specific portion;
By flat-pressing the portion where the protrusion is formed so as to eliminate the protrusion, the width of the gap is narrowed, and a flat surface suitable for holding components around the gap is formed. Flat pressing process;
The frame material is punched out so that one and the other of the portions where the flat surfaces on both sides of the narrowed gap are formed are the component mounting frame element and the adjacent frame element, respectively. A second punching process to be formed;
A method for manufacturing a lead frame.

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