JP2009038196A - Electronic device and wire bonding method - Google Patents

Abstract

In a wire bonding method in which a wire is connected to a lead frame having a groove formed on the surface by press working, the wire connecting portion in the lead frame can be supported by the support base without being lifted from the support base and bonded. To.
A portion 30b of the lead frame 30 that is positioned on the opposite side of the connecting portion 30a of the wire 50 from the groove 35 is positioned horizontally, and the lower surface 32 of the lead frame 30 is oriented in the ground direction. The lead frame 30 is bent at the groove 35 so that the connecting portion 30a of the wire 50 is bent downward from the groove 35, and the bent lead frame 30 is supported by the support base 300. By mounting and pressing on the flat surface 310, the straight shape is restored and wire bonding is performed in this state.
[Selection] Figure 2

Description

  The present invention relates to a wire bonding method for connecting a wire to a lead frame in which grooves are formed on at least one of the front and rear surfaces by pressing, and to a lead frame in which such grooves are formed. The present invention relates to an electronic device having a structure.

  A general resin-sealed type electronic device is configured by connecting an electronic device and a lead frame with bonding wires and sealing them so as to be wrapped with a mold resin. Here, in general, in wire bonding, a wire is connected to the lead frame while the lead frame is supported on a flat surface of a support base.

A lead frame used in such an electronic device has a surface and a surface opposite to each other, for example, a plate-like one, like a general one. Since the lead frame is sealed with the mold resin, it has been conventionally practiced to form a groove for preventing the mold resin from peeling off by pressing at least one of the one side and the other side of the lead frame. (For example, refer to Patent Document 1).
JP 2006-32774 A

  Based on the prior art, the present inventor conducted a trial study on a wire bonding method for a lead frame having such a groove. FIG. 10 is a process diagram showing a cross-sectional view of the wire bonding process in this trial study.

  The support base 300 has a flat surface 310, and the lead frame 30 is mounted on and supported by the flat surface 310. Here, the lead frame 30 has grooves 35 formed on both the one surface 31 to which the wire 50 is connected and the other surface 32 opposite to the one surface 31, and the lead frame 30 has the other surface 32 in a flat surface 310. Is mounted on the flat surface 310.

  The end portion of the one surface 31 of the lead frame 30 that is located on the opposite side of the wire 50 from the connection portion 30a is pressed against the flat surface 310 by a pressing jig (not shown). Fixed to a flat surface 310. Then, the wire 50 is connected to the one surface 31 of the lead frame 30 in such a fixed state.

  However, since the lead frame 30 is provided with the groove 35 by press working, the lead frame 30 is bent from the groove 35 portion due to pressure during processing. Although the lead frame 30 is warped by this bending, the direction of the warping is random and cannot be determined in a certain direction.

  Therefore, in some cases, as shown in FIG. 10, when the lead frame 30 is pressed and fixed on the flat surface 310 of the support base 300, the portion on the connection portion side of the wire 50 is separated from the portion of the groove 35. It floats on the opposite side of the flat surface 310, that is, upward. In such a case, when wire bonding is performed, transmission of ultrasonic vibration is hindered, which causes bonding failure.

  Further, as a method of providing the above-mentioned groove in the lead frame, there is a method by cutting or etching other than the press working, but in this case, the warp as in the press working hardly occurs. However, there is a problem that the man-hour for providing the groove is increased and the productivity is lowered as compared with the press working.

  The present invention has been made in view of the above problems, and in a wire bonding method for performing wire connection to a lead frame formed by forming grooves on the surface by press working, the wire connection portion in the lead frame is connected from the support base. It is intended to be able to bond by supporting on a support stand without floating.

  In order to achieve the above object, the present invention relates to the step of placing the lead frame (30) into the groove (35) before mounting the lead frame (30) on the flat surface (310) of the support base (300). And bend.

  Here, in this bending, the part (30b) located on the opposite side of the lead frame (30) from the groove (35) on the side opposite to the connection part (30a) of the wire (50) is positioned horizontally, and When the other surface (32) of the lead frame (30) is directed to the ground direction, the connecting portion (30a) of the wire (50) is bent downward from the groove (35). In addition, the lead frame (30) is bent, and the bent lead frame (30) is mounted on the flat surface (310) of the support base (300) and pressed down, whereby a flat surface ( 310), the lead frame (30) is returned to a straight shape, and wire bonding is performed in this state (see FIG. 2 described later). Such a wire bonding method is the first feature of the present invention.

  According to this, the lead frame (30) is pressed against the support base (300) by determining the warping direction of the lead frame (30) so as to protrude in a direction away from the flat surface (310) of the support base (300). Since (30) can be straightly deformed, the connecting portion (30a) of the wire (50) of the lead frame (30) in which the groove (35) is formed by press working is floated from the support base (300). It is possible to perform bonding without being supported on the support base (300).

  Here, the groove (35) is formed on both the one surface (31) and the other surface (32) of the lead frame (30), and the lead frame (30) is bent on the one surface (31) side. You may make it carry out by forming a groove | channel (35) so that the groove | channel (35) of the other surface (32) side may become deeper than (35) (refer FIG. 3 mentioned later).

  According to this, the lead frame (30) can be bent simultaneously with the formation of the groove (35), which is efficient.

  Furthermore, in this case, in the formation of the groove (35), if the position of the groove (35) on the one surface (31) side and the groove (35) on the other surface (32) side are shifted (described later). 4), it is preferable because the lead frame (30) can be prevented from being thinned by the formation of the groove (35).

  Further, the groove (35) has the same depth formed on both the one surface (31) and the other surface (32) of the lead frame (30), and the lead frame (30) is bent on one surface ( After the groove (35) is formed on the 31) side, the groove (35) may be formed in the order of forming the groove (35) on the other surface (32) side.

  Further, when the groove (35) is formed on both the one surface (31) and the other surface (32) of the lead frame (30), the groove (35) on the one surface (31) side may be bent (described later). FIG. 5). According to this, it is preferable to realize the bent shape of the lead frame (30) described above.

  Further, according to the present invention, in the step of forming the groove (35) on at least one of the one surface (31) and the other surface (32) of the lead frame (30), the one surface (31) of the lead frame (30) is formed. Of these, the second feature is to form grooves (35) on both sides of the connecting portion (30a) of the wire (50) (see FIG. 7 described later).

  According to this, the connecting portion (30a) of the wire (50) is sandwiched between both grooves (35) on the one surface (31) side, and the portion sandwiched between the both grooves (35) is straight. If this part is supported on the flat surface (310) of the support base (300), the connection part (30a) of the wire (50) of the lead frame (30) is supported without being lifted from the support base (300). It is possible to perform bonding while supporting the table (300).

  Further, according to the present invention, the warped shape of the lead frame (30) in which the groove (35) is formed is obtained in advance, and the surface (310) on which the lead frame (30) is mounted serves as the support base (300). The third feature is to use a frame (30) having an inclination following the warped shape (see FIG. 8 described later).

  According to this, since the surface (310) on which the lead frame (30) is mounted in the support base (300) has an inclination following the warped shape of the lead frame (30), the wire (50) of the lead frame (30). It is possible to bond the connecting portion (30a) to the support base (300) without floating from the support base (300).

  The present invention also includes a lead frame (30) in which a groove (35) is formed on at least one of the one surface (31) and the other surface (32) by pressing, and the electronic component (10) and the lead frame (30). In the electronic device in which the one surface (31) is connected by the bonding wire (50), the lead frame (30) is located on the opposite side of the groove (35) from the connecting portion (30a) of the wire (50). When the portion (30b) that is positioned is positioned horizontally and the other surface (32) of the lead frame (30) is oriented in the ground direction, the connecting portion (30a) of the wire (30) is The fourth feature is that the groove is bent downward from the groove (35) (see FIG. 1 described later).

  The present invention is appropriately manufactured by the wire bonding method having the first feature, and the effect is the same as described above.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1A is a diagram showing a schematic cross-sectional configuration of the electronic device 100 according to the first embodiment of the present invention. FIG. 1B shows a wire bonding connection portion of a lead frame 30 in the electronic device 100. It is a partial schematic plan view shown.

  In the following description, the upper surface and the lower surface of each component of the electronic device 100 are the upper surface and the lower surface of each component in FIG. It only means a surface to be positioned, and does not limit the vertical relationship corresponding to the actual top-and-bottom direction. That is, the upper surface of a certain component is one surface of the component, and the lower surface is the other surface located on the opposite side of the one surface.

  The electronic device 100 is roughly formed by sealing an electronic component 10 and a lead frame 30 electrically connected via a bonding wire 50 with a mold resin 40 as a sealing material.

  The electronic component 10 is not particularly limited as long as it is a surface mount component such as an IC chip, a capacitor, and a resistance element. However, in the example shown in FIG. 1, the electronic component 10 is shown as an IC chip made of a silicon semiconductor. Has been.

  The electronic component 10 is mounted and fixed on the upper surface 21 of the die pad 20 via a die mount material (not shown) made of solder, Ag paste, or the like. The die pad 20 may be a heat sink fixed to the lead frame 30 by caulking or the like, but here is formed of an island formed integrally with the lead frame 30.

  The lead frame 30 is made of a general lead frame material such as copper or iron, and is disposed around the die pad 20 inside the mold resin 40. Although a plurality of lead frames 30 are arranged in the present embodiment, one lead frame 30 may be provided in some cases.

  The lead frame 30 has a plate shape having an upper surface 31 and a lower surface 32 which are front and back plate surfaces. Here, the lead frame 30 has an elongated plate shape in which one end portion is located on the electronic component 10 side and a portion on the other end side extends on the opposite side to the electronic component 10 in the same manner as a general one. Yes.

  The electronic component 10 and the upper surface 31 of the lead frame 30 are electrically connected by a bonding wire 50. Here, the bonding wire 50 is made of general Au (gold), Al (aluminum), or the like, and is formed by ordinary wire bonding.

  Further, as the mold resin 40, a mold material usually used for this type of mold package, for example, a thermosetting resin such as an epoxy resin can be adopted. Here, as shown in FIG. 1, the mold resin 40 has a general rectangular plate shape in which an upper surface 41 and a lower surface 42 which are front and back plate surfaces are rectangular. The outer shape of the mold resin 40 substantially constitutes the outer shape of the electronic device 100.

  The lower surface 42 of the mold resin 40 is a facing surface that faces the member to be bonded when the electronic device 100 is connected to a member to be bonded such as a wiring board or a bus bar (not shown). Further, the surface 43 located on the outer periphery of the upper surface 41 and the outer surface of the lower surface 42 of the mold resin 40 is a side surface 43 constituting the outer peripheral end of the mold resin 40.

  In the electronic device 100, as shown in FIG. 1, the inner lead portion, which is a portion to which the bonding wire 50 is connected, is covered with the mold resin 40 in the lead frame 30, and the outer lead portion is molded resin. It protrudes from the side surface 43 of 40 and is exposed.

  The outer lead portion is a portion that is electrically connected to the member to be joined via solder, conductive adhesive, or the like. Here, the outer lead portion includes a root portion and a tip portion on the mold resin 40 side. It is the shape bent in the middle part. This bent shape is common, and in this case, the outer lead portion is usually connected to the member to be joined at the tip portion.

  Here, the inner lead portion of the lead frame 30 is provided with a groove 35 for preventing the mold resin 40 from peeling off. Here, the groove 35 is formed on both the upper surface 31 and the other surface 32 of the lead frame 30 by pressing.

  The groove 35 of the present embodiment is formed by pressing the mold 200 against the upper and lower surfaces 31 and 32 of the lead frame 30 as shown in FIG.

  Further, as shown in FIG. 1A, the inner lead portion of the lead frame 30 has a connection portion 30 a of the wire 50 that is a portion to which the wire 50 is connected across the groove 35, and the groove 35. It is comprised by the site | part 30b (henceforth a wire connection part opposite part 30b) located in the opposite side to the connection part 30a of the wire 50. FIG.

  In FIG. 1A, the wire connection portion opposite portion 30b is positioned so as to extend in the horizontal direction (the left-right direction in FIG. 1A). Further, the lower surface 32 of the lead frame 30 is in a state of facing the ground direction (downward in FIG. 1A). In this state, the wire connecting portion 30a is bent downward from the groove 35.

  Next, a method for manufacturing the electronic device 100 of this embodiment will be described. FIG. 2 is a process diagram showing a method of manufacturing a wire bond structure, that is, a wire bonding method in the present manufacturing method. This wire bonding method includes a step of forming a groove 35 in the lead frame 30 (groove forming step), and then a step of connecting the wire 50 to the lead frame 30 (connecting step).

  First, the material plate of the lead frame 30 is patterned into a shape having the die pad 20 and the lead frame 30 by etching or pressing. In this way, as shown in FIG. 2A, the lead frame 30 having the upper surface 31 and the other surface 32 that are in the front and back positions is prepared. At this stage, the die pad 20 and the lead frame 30 are integrally connected via a tie bar or a suspension lead (not shown).

  Next, in the groove forming step, grooves 35 are formed on the upper surface 31 and the lower surface 32 of the lead frame 30 by pressing. Specifically, as shown in FIGS. 2A and 2B, grooves are formed on the upper and lower surfaces 31, 32 by pressing the mold 200 against the upper surface 31 and the lower surface 32 of the lead frame 30. 35 is formed.

  Next, the electronic component 10 is mounted and fixed on the upper surface 21 of the die pad 20 via the above-described die mount material (not shown). Next, a connection process is performed. In this connection step, as shown in FIG. 2C, a support base 300 having a flat surface 310 is prepared, and the lower surface 32 of the lead frame 30 in which the groove 35 is formed is opposed to the flat surface 310. The lead frame 30 is mounted on the flat surface 310 of the support base 300.

  Next, as shown in FIG. 2D, in this state, the lead frame 30 is pressed against the flat surface 310 and fixed. This fixing is performed by pressing a portion of the upper surface 31 of the lead frame 30 on the side opposite to the connection portion 30 a of the wire 50 with the pressing jig 400. Then, the wire 50 is connected to the upper surface 31 of the lead frame 30 by wire bonding while being pressed and fixed in this way.

  The above is the basic operation in the present wire bonding method. In the present bonding wire method, the following unique devices are further added. That is, in the present embodiment, before the lead frame 30 is mounted on the support base 300, the lead frame 30 is bent at the groove 35.

  In this state, the lead frame 30 is bent into a shape that protrudes upward from the support table 300 at the groove 35 before the lead frame 30 is mounted on the support table 300 and pressed. (See FIG. 2 (c)).

  That is, the lead frame 30 is bent at the groove 35 so that the upper surface 31 side is convex and the lower surface 32 side is concave. The lower surface 32 of the lead frame 30 is a surface that faces the flat surface 310 when the lead frame 30 is mounted on the flat surface 310 of the support base 300.

  As shown in FIG. 2 (c), this bending causes this state when the wire connection portion opposite portion 30b is positioned horizontally and the lower surface 32 of the lead frame 30 faces the ground. , The wire connection portion 30a is bent so as to be lowered from the groove 35, that is, toward the ground.

  In this embodiment, the groove forming process also serves as a bending process, and the bending process is performed at the same time as the groove forming process to improve work efficiency. That is, in the present embodiment, the lead frame 30 is bent at the same time as the formation of the groove 35 by using the pressure at the time of forming the groove 35 by press working on the lead frame 30.

  FIG. 3 is a process diagram specifically illustrating the bending method of the present embodiment. As described above, in the present embodiment, the grooves 35 are formed in the upper and lower surfaces 31 and 32 by pressing the mold 200 against the upper surface 31 and the lower surface 32 of the lead frame 30. At this time, as shown in FIG. 3, the groove 35 on the lower surface 32 side is formed deeper than the groove 35 on the upper surface 31 side of the lead frame 30.

  In general, when a groove is formed by press working, the deeper the groove, the larger the pressure during processing. Therefore, by forming the groove 35 on both sides 31 and 32 so that the groove 35 on the lower surface 32 side of the both surfaces 31 and 32 of the lead frame 30 is deeper, the upper surface 31 of the lead frame 30 is convex. The bent shape is such that the lower surface 32 is concave.

  After the bending process, in the connecting process, the lead frame 30 is mounted on the support base 300, and the lead frame 30 is elastically bent at the groove 35 by pressing, so that the lead frame 30 is flat on the support base 300. The surface 310 is restored to a straight shape following the surface 310 (see FIG. 2D). In this state, wire bonding is performed.

  Thus, with the completion of the connection process, the wire bonding of the present embodiment is completed, and the electronic component 10 and the lead frame 30 are connected via the bonding wire 50. After that, when the lead frame 30 is separated from the support base 300, as shown in FIG. 2 (e), the lead frame 30 returns to the bent shape again by the elastic force.

  Thereafter, the electronic component 10 and the lead frame 30 in which the wire bonding connection is completed are placed in a mold mold (not shown), and a mold resin 40 such as an epoxy resin melted by heating is injected into the mold mold.

  As a result, the electronic component 10, the lead frame 30, the bonding wire 50, and the die pad 20 are sealed with the mold resin 40. After the mold resin 40 is cooled and solidified, the workpiece is taken out of the mold, whereby the package molding using the mold resin 40 is completed.

  Thereafter, the lead frame 30 is formed by cutting off the die pad 20, cutting off the lead frame 30 at the outer lead portion, or performing bending, thereby completing the electronic device 100 of this embodiment.

  As described above, according to the wire bonding method of the present embodiment, since the lead frame 30 is bent into the above-described shape at the groove 35 before the connecting step, it is flat when mounted on the support base 300. The warping direction of the lead frame 30 is determined so that the lead frame 30 is convex in a direction away from the surface 310.

  Accordingly, the lead frame 30 can be straightly deformed along the flat surface 310 by being pressed against the support base 300. Therefore, according to the present wire bonding method, the connecting portion 30a of the wire 50 of the lead frame 30 in which the groove 35 is formed by press working can be supported and bonded to the support base 300 without floating from the support base 300. It becomes.

  In this wire bonding method, the groove 35 is formed on the upper and lower surfaces 31 and 32 of the lead frame 30 by pressing, and the groove 35 on the lower surface 32 side is deeper than the groove 35 on the upper surface 31 side. As described above, since the lead frame 30 is bent by forming the groove 35, the formation of the groove 35 and the bending of the lead frame 30 can be performed simultaneously, which is efficient.

  Here, although the dimensions are not limited, a specific example of the bending shape in the bending step will be described using the dimensions L, t, and θ shown in FIG.

  The dimension L is the length L of the connecting portion 30 a of the wire 50 on the upper surface 31 side of the lead frame 30, and the dimension t is the thickness t of the lead frame 30. Further, the angle θ is an angle θ formed by the connection portion 30a of the wire 50 and the wire connection portion opposite portion 30b on the one surface 31 side of the lead frame 30 after bending, that is, the bending angle θ.

  Here, when 0.5 mm <t <1.5 mm and 0.5 mm <L <1.5 mm, the bending angle θ is preferably greater than 0 and less than 10 °. In this case, if the bending angle θ is 10 ° or more, it is likely to be difficult to straighten the lead frame 30 by mounting and pressing on the support base 300.

  In addition, as described above, according to the present embodiment, the electronic component 10 and the lead frame 30 in which the groove 35 is formed on the upper and lower surfaces 31 and 32 by press working are provided, and the upper surface of the electronic component 10 and the lead frame 30 is provided. An electronic device 100 is provided in which 31 is connected by a bonding wire 50.

  In the electronic device 100, by using the wire bonding method described above, the wire connection portion opposite portion 30b of the lead frame 30 is positioned horizontally, and the lower surface 32 of the lead frame 30 is directed in the ground direction. The electronic device 100 is provided that is bent so that the connecting portion 30a of the wire 30 is lowered downward from the groove 35 when in the state. And as mentioned above, such an electronic device 100 is appropriately manufactured using the wire bonding method of this embodiment.

(Second Embodiment)
FIG. 4 is a process diagram specifically illustrating a bending process in the wire bonding method according to the second embodiment of the present invention. The present embodiment is different from the wire bonding method shown in the first embodiment in that the bending process is partially deformed.

  Also in the bending process of the present embodiment, the groove on the lower surface 32 side than the groove 35 on the upper surface 31 side is utilized by using the pressure at the time of forming the groove 35 by press working on the lead frame 30 in order to increase the efficiency of the work. By forming both grooves 35 so that 35 is deeper, the lead frame 30 is bent into the above shape simultaneously with the formation of the grooves 35.

  Here, if the groove 35 on the lower surface 32 side is deeper than the groove 35 on the upper surface 31 side of the lead frame 30, when the grooves 35 on the both surfaces 31 and 32 are at the same position, The lead frame 30 may become thin, and the mechanical strength of the lead frame 30 may be reduced.

  In consideration of this point, in this embodiment, in the groove forming step, the positions of the groove 35 on the upper surface 31 side and the groove 35 on the lower surface 32 side of the lead frame 30 are shifted from each other. Thus, if the groove 35 on the upper surface 31 side and the groove 35 on the lower surface 32 side are shifted, the thinning of the lead frame 30 due to the formation of the groove 35 is suppressed compared to the case where both the grooves 35 are in the same position. can do.

  Thus, after performing the bending and groove forming step, the wire connection by the wire bonding method of the present embodiment is completed by performing the connection step in the same manner as described above. Thereafter, similar to the above, if sealing with the mold resin 40 is performed, the present embodiment is the same as that shown in FIG. 1 except that the positions of the grooves 35 of the upper and lower surfaces 31 and 32 are shifted. The electronic device is manufactured.

  Even in the wire bonding method of the present embodiment, the position of the groove 35 on the upper surface 31 side and the groove 35 on the lower surface 32 side are shifted, but the lead frame 30 is bent as in the first embodiment. Therefore, the connection portion 30a of the wire 50 of the lead frame 30 can be bonded to the support base 300 without being lifted from the support base 300.

(Third embodiment)
The third embodiment of the present invention provides a bending step in the wire bonding method. The folding process of this embodiment can be applied to the groove forming process as the bending process shown in the first and second embodiments.

  That is, in the bending and groove forming process of the present embodiment, in the groove formation shown in FIG. 3 and FIG. 4, the groove 35 is first formed on the upper surface 31 side of the lead frame 30 by pressing, and then the lower surface 32 side. Both grooves 35 are formed in the order of forming the grooves 35 by pressing. In this way, the lead frame 30 is bent into the above shape simultaneously with the formation of the groove 35.

  In particular, if the grooves 35 on the upper and lower surfaces 31 and 32 are formed in the order of forming the groove 35 on the lower surface 32 side later, even if the grooves 35 on the upper and lower surfaces 31 and 32 have the same depth, Simultaneously with the formation of the groove 35, the lead frame 30 is bent into the above shape.

  That is, if the order of groove formation as in the present embodiment is used, it is not necessary to make the depths of the grooves 35 of the upper and lower surfaces 31, 32 different in order to bend the lead frame 30 in the same manner as described above. Then, the connection portion 30 a of the wire 50 of the lead frame 30 can be supported and bonded to the support base 300 without being lifted from the support base 300.

(Fourth embodiment)
FIG. 5 is a process diagram showing the main part of the bending process in the wire bonding method according to the fourth embodiment of the present invention. The present embodiment is applicable to the groove forming process as the bending process shown in the first to third embodiments, and in these groove forming processes, the plane of the groove 35 on the upper surface 31 side of the lead frame 30 is applied. The place where the shape was changed is different.

  In the bending and groove forming step of the present embodiment, the groove 35 on the upper surface 31 side of the lead frame 30 is bent. That is, the planar shape of the groove 35 on the upper surface 31 side is not a single straight line but a pattern having a bent portion. This can be realized by changing the mold shape.

  According to this, compared with the case where the planar shape of the groove 35 on the upper surface 31 side is a single straight line, the bending force that becomes concave on the upper surface 31 side in the lead frame 30 is weakened. Therefore, according to this embodiment, it is easy to realize the bent shape of the lead frame 30 described above.

  The bent shape of the groove 35 on the upper surface 31 side is not limited to the V shape shown in FIG. As shown in FIGS. 6A to 6H, the curved shape of the groove 35 on the upper surface 31 side may be a curved shape, a cross shape, a zigzag shape, or the like. The effect of form is demonstrated.

(Fifth embodiment)
FIG. 7 is a process diagram specifically illustrating a groove forming process in the wire bonding method according to the fifth embodiment of the present invention.

  The wire bonding method according to the present embodiment also includes a groove forming step for forming the groove 35 in the lead frame 30 and a connecting step for connecting the wire 50 to the lead frame 30 thereafter, as described above.

  Here, in the present embodiment, in the groove forming step, the grooves 35 are formed by pressing on both sides of the connection portion 30a of the wire 50 in the upper surface 31 of the lead frame 30, respectively. Here, the groove 35 is similarly formed on the lower surface 32 of the lead frame 30, but the groove 35 may not be formed on the lower surface 32 side, and may be only on the upper surface 31 side.

  According to this, the connection portion 30a of the wire 50 is sandwiched between both the grooves 35 on the upper surface 31 side, and the portion sandwiched between the both grooves 35 is straight. In the lead frame 30, the portions on the outer side of the grooves 35 on both sides of the connecting portion 30 a of the wire 50 may be bent in any direction.

  Then, if the connecting portion 30a of the straight wire 50 is supported on the flat surface 310 (see FIG. 2) of the support base 300, the connection portion 30a of the wire 50 is bonded without floating from the support base 300. It becomes possible.

(Sixth embodiment)
FIG. 8 is a process diagram specifically illustrating a connection process in the wire bonding method according to the fifth embodiment of the present invention.

  The wire bonding method according to the present embodiment also includes a groove forming step for forming the groove 35 in the lead frame 30 and a connecting step for connecting the wire 50 to the lead frame 30 thereafter, as described above.

  Here, in this embodiment, in the groove forming step, the grooves 35 are formed by pressing as in the conventional case. In this case, the lead frame 30 is bent at the groove 35. However, in the wire bonding method of the present embodiment, the bent shape of the lead frame 30 is obtained in advance before the connecting step, and any bent state is obtained. Know if it is.

  In the connecting step, a support base 300 having a surface 310 on which the lead frame 30 is mounted has an inclination that follows the warped shape of the lead frame 30 that has been obtained in advance. Here, in FIG. 8, the inclination angle θ ′ is shown.

  According to this, since the lead frame 30 is supported in close contact with the support base 300 along the inclination, it is possible to bond the connecting portion 30a of the wire 50 without floating from the support base 300.

  Here, the inclination angle θ ′ in FIG. 8 is determined according to the load when the wire 50 is pressed against the connection portion 30a of the wire 50 by the wire bonding tool at the time of wire bonding, that is, the bonding load.

  FIG. 9 is a diagram showing a result of investigation by the present inventor regarding the relationship between the bonding load and the inclination angle θ ′. As shown in FIG. 9, as the bonding load increases, the inclination angle θ ′ for bringing the lead frame 30 into close contact with the support base 300 along the inclination decreases linearly.

  That is, if the inclination angle θ ′ is determined so as to satisfy the relationship shown in FIG. 9, the above-described effect of the present embodiment is exhibited. For example, in FIG. 9, when the bonding load is 200 g, the inclination angle θ ′ may be set to about 2.9 °.

(Other embodiments)
In the wire bonding methods shown in the first to fourth embodiments, the lead frame 30 that is sealed by the mold resin 40 and has the upper and lower surfaces 31 and 32 that are located on the front and back sides. The groove 35 for preventing peeling of the mold resin 40 is formed on both the upper and lower surfaces 31 and 32 by pressing, but the groove 35 is formed on only one of the upper and lower surfaces 31 and 32. There may be.

  Also in this case, the lead frame 30 may be bent so that the upper surface 31 is convex and the lower surface 32 is concave, as described above. In the case where the groove 35 is formed only on the lower surface 32, this bending can be realized by the pressure during the processing of the groove.

  When the groove 35 is formed only on the upper surface 31 of the lead frame 30, for example, after the formation of the groove 35, a separate bending process of the lead frame 30 is provided, Thus, the lead frame 30 may be bent at the groove 35.

  That is, in the first to fourth embodiments, the lead frame 30 is bent at the same time as the formation of the groove 35 in the lead frame 30, and the bending uses the pressure at the time of forming the groove 35. Then, it may be performed simultaneously with the groove forming step, or may be separately bent after the groove forming step and before the connecting step.

  Further, the form of sealing the lead frame 10 with the mold resin 40 in the semiconductor device is not limited to that shown in FIG. In the example shown in FIG. 1, the sealing form is applied to a QFP (quad flat package) having an outer lead, but even a QFN (quad flat non-lead package) having no outer lead is used. Good.

  Furthermore, the electronic device may not be sealed with a mold resin. That is, the lead frame 30 only needs to have a groove 35 formed by press working on at least one of the upper surface 31 and the other surface 32, and the groove 35 is not limited to the prevention of mold resin peeling. .

(A) is a schematic sectional drawing of the electronic device which concerns on 1st Embodiment of this invention, (b) is a partial schematic plan view which shows the wire bonding connection part in the same electronic device. It is process drawing which shows the wire bonding method which concerns on 1st Embodiment. It is process drawing which shows the bending method of 1st Embodiment concretely. It is process drawing which shows the bending process in the wire bonding method which concerns on 2nd Embodiment of this invention. It is process drawing which shows the principal part of the bending process in the wire bonding method which concerns on 4th Embodiment of this invention. It is a top view which shows the various examples of the bending shape of the groove | channel on the upper surface side in the bending process which concerns on 4th Embodiment. It is process drawing which shows the groove | channel formation process in the wire bonding method which concerns on 5th Embodiment of this invention. It is process drawing which shows the connection process in the wire bonding method which concerns on 5th Embodiment of this invention. It is a figure which shows the relationship between a bonding load and inclination | tilt angle (theta) '. It is process drawing which shows the wire bonding process in trial manufacture examination of this inventor.

Explanation of symbols

10 ... electronic component, 30 ... lead frame, 30a ... wire connection,
30b ... The wire connection part opposite part as a part located in the lead frame on the opposite side to the wire connection part from the groove,
31 ... Upper surface of the lead frame, 32 ... Lower surface of the lead frame, 35 ... Groove,
50 ... bonding wire, 300 ... support base, 310 ... flat surface.

Claims (8)

A lead frame (30) having one surface (31) and the other surface (32) in the front and back positions is prepared, and a groove (35) is formed on at least one of these one surface (31) and the other surface (32) by pressing. Forming, and
A support base (300) having a flat surface (310) is prepared, and the other surface (32) of the lead frame (30) in which the groove (35) is formed is opposed to the flat surface (310). Meanwhile, the lead frame (30) is mounted on the flat surface (310) of the support base (300), and in this state, the lead frame (30) is pressed against the flat surface (310). A wire bonding method comprising: connecting a wire (50) to the one surface (31) of the lead frame (30) by wire bonding while fixing,
Before mounting the lead frame (30) on the flat surface (310) of the support base (300), the lead frame (30) is bent at the groove (35),
In the bending, the part (30b) located on the opposite side of the lead frame (30) to the connection part (30a) of the wire (50) with respect to the groove (35) is positioned horizontally, and When the other surface (32) of the lead frame (30) is in the ground direction, the connecting portion (30a) of the wire (50) is bent downward from the groove (35). The lead frame (30) is bent so as to have a shape,
The bent lead frame (30) is mounted on the flat surface (310) of the support base (300) and pressed down, thereby the lead frame (30) along the flat surface (310). ) To a straight shape, and in this state, the wire bonding is performed. The groove (35) is formed on both the one surface (31) and the other surface (32) of the lead frame (30),
The lead frame (30) is bent so that the groove (35) on the other surface (32) side is deeper than the groove (35) on the one surface (31) side. 35. The wire bonding method according to claim 1, which is performed by forming (35). In forming the groove (35), the groove (35) on the one surface (31) side and the groove (35) on the other surface (32) side are shifted from each other. 3. The wire bonding method according to 2. The groove (35) is formed to have the same depth on both the one surface (31) and the other surface (32) of the lead frame (30),
In bending the lead frame (30), the groove (35) is formed on the one surface (31) side, and then the groove (35) is formed on the other surface (32) side. The wire bonding method according to claim 1, wherein the wire bonding method is performed. The wire bonding method according to any one of claims 2 to 4, wherein the groove (35) on the one surface (31) side is bent. A lead frame (30) having one surface (31) and the other surface (32) in the front and back positions is prepared, and a groove (35) is formed on at least one of these one surface (31) and the other surface (32) by pressing. Forming, and
A support base (300) having a flat surface (310) is prepared, and the other surface (32) of the lead frame (30) in which the groove (35) is formed is opposed to the flat surface (310). Meanwhile, the lead frame (30) is mounted on the flat surface (310) of the support base (300), and in this state, the lead frame (30) is pressed against the flat surface (310). A wire bonding method comprising: connecting a wire (50) to the one surface (31) of the lead frame (30) by wire bonding while fixing,
The wire bonding method, wherein the grooves (35) are formed on both sides of the connecting portion (30a) of the wire (50) in the one surface (31) of the lead frame (30). A lead frame (30) having one surface (31) and the other surface (32) in the front and back positions is prepared, and a groove (35) is formed on at least one of these one surface (31) and the other surface (32) by pressing. Forming, and
The lead frame (30) in which the groove (35) is formed is mounted on a support base (300) and pressed against the support base (300) to fix the lead frame (30) to the lead frame (30). A wire bonding method comprising: connecting a wire (50) by bonding;
The warpage shape of the lead frame (30) in which the groove (35) is formed is obtained in advance,
A wire bonding method characterized in that a surface (310) on which the lead frame (30) is mounted has an inclination that follows the warped shape of the lead frame (30) as the support base (300). An electronic component (10);
A lead frame having one surface (31) and the other surface (32) which are in the front and back positions, and a groove (35) formed in at least one of the one surface (31) and the other surface (32) by pressing. 30)
In the electronic device in which the electronic component (10) and the one surface (31) of the lead frame (30) are connected by a bonding wire (50),
A portion (30b) of the lead frame (30) located on the opposite side of the groove (35) from the connecting portion (30a) of the wire (50) is positioned horizontally and the lead frame ( 30) When the other surface (32) of the wire (30) is oriented in the ground direction, the connecting portion (30a) of the wire (30) is bent downward from the groove (35). An electronic device characterized by comprising:

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