JP2008135578A - Wire bonding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wire bonding method by which a stable loop can be formed with little variations in shape and with a wide allowable range of an amount of wire, even when the reverse operation for the formation of a loop is constrained. <P>SOLUTION: In this wire bonding method, the end of a capillary 22 which reels out a wire 23 between a first bond, where the wire 23 is bonded to a pad 19 of a semiconductor chip, and a second bond where the wire 23 is bonded to a lead 14 on the package side goes through a bend formation point. Since the bend formation point is located on the center side of the semiconductor chip with the pad 19 as a reference, in a direction of a straight line connecting between the pad 19, which is the first bond and the lead 14 which is the second bond, and is located higher than a glass 20 formed integrally on top of the semiconductor chip, the glass 20 and the wire 23 are brought into contact with each other by the time, until the end of the capillary 22 goes via the bend formation point. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wire bonding method and relates to a technique for forming a stable loop.

  First, a semiconductor device in which wire bonding is performed will be described. 15 and 16 are a perspective view and a side view of the semiconductor device before the wire bonding in the middle of manufacture. 15 and 16, the semiconductor device 11 has a die pad 13 at the center of the ceramic package 12 that serves as a base.

  There are raised portions on both sides of the die pad 13, and a plurality of leads 14 for performing the second bond of wire bonding are provided in a row. Side walls 15 that are higher than the leads 14 are provided on the entire circumference of the ceramic package 12, and a plurality of external terminals 16 are provided on the back surface at an equal pitch.

  The ceramic package 12 is produced by stacking and sintering a plurality of layers of materials. The lead 14 and the external terminal 16 are portions formed by printing a metal paste on a material layer, and both are connected through the side surface. A semiconductor chip 18 is bonded to the die pad 13 with an adhesive paste 17. The semiconductor chip 18 is an image sensor, and a pixel region is provided at the center side, and a plurality of pads 19 on which wire bonding first bonding is performed are provided in the vicinity of both sides.

  A glass 20 is bonded on the semiconductor chip 18 with an adhesive 21. The glass 20 has a role of protecting the semiconductor chip 18 and transmitting light to a pixel region provided in the semiconductor chip 18. Although the glass 20 is slightly smaller than the semiconductor chip 18, the glass 20 has a size such that the end portion is close to the pad 19 so that the pixel region provided in the central portion of the semiconductor chip 18 can be maximized. The glass 20 may be bonded to the upper surface of the ceramic package 12 so as to have a gap with the semiconductor chip 18, but here, the glass 20 is directly bonded to the semiconductor chip 18 in order to reduce the thickness.

  Next, the connection between the pad 19 and the lead 14 of the semiconductor device 11 by the conventional wire bonding method will be described with reference to FIGS. 17 is a side view showing the state before pad connection, FIG. 18 is a side view showing the state at the time of pad connection, FIG. 19 is a side view for explaining the rise to the top point after pad connection, and FIG. It is a side view showing the state of.

  17 to 20, reference numeral 22 denotes a capillary used for wire bonding, which has a cylindrical shape, and a wire 23 is passed through the capillary. Reference numeral 24 denotes a wire clamper provided on the upper part of the capillary 22, which operates integrally with the capillary 22 and controls the relative movement of the wire 23 relative to the capillary 22 by opening and closing thereof.

As will be described below, the wire bonding is performed while the ceramic package 12 on which the semiconductor chip 18 is mounted is pressed and fixed on the apparatus and heated.
That is, as shown in FIG. 17, in wire bonding, the wire clamper 24 is closed, and an initial ball 25 is formed by discharge on the tip of the wire 23 protruding from the tip of the capillary 22.

  Next, the wire clamper 24 is opened, and as shown in FIG. 18, the initial ball 25 is pressed against the pad 19 of the semiconductor chip 18 by lowering the capillary 22, and one end of the wire 23 is joined to the pad 19 by the action of heat and ultrasonic waves. A first bond is made.

  Thereafter, as shown in FIG. 19, the capillary 22 moves upward while feeding the wire 23, and after the capillary 22 reaches the uppermost point, as shown in FIG. 20, the lead 14 that is the connection destination of the other end of the wire 23. A loop is formed by performing an arc-shaped descending action toward. Thereafter, a second bond is performed in which the wire 23 is pressed against the lead 14 to join the other end of the wire 23 to the lead 14.

  The loop formed by this wire bonding method does not operate the capillary 22 in the reverse operation, that is, in the direction opposite to the lead 14. For this reason, the loop is a triangular loop having a natural bending shape corresponding to the material of the wire 23 on the side close to the pad 19.

  Thereafter, the capillary 22 is raised, and the wire clamper 24 is closed in the middle of the raising, thereby disabling the relative movement of the wire 23 with respect to the capillary 22 and tearing the wire 23. At this time, the wire 23 comes out from the tip of the capillary 22 in the same state as the beginning.

Next, the operations described above are repeated to sequentially connect the pads 19 of the semiconductor chip 18 and the leads 14 of the ceramic package 12.
The reason why the reverse operation is not performed in the above-described operation will be described with an example. The height difference between the upper surface of the semiconductor chip 18 and the upper surface of the glass 20 indicated by the symbol A in FIG. 16 is 300 μm. Although the end face of the glass 20 has a positional variation of ± 30 μm with respect to the semiconductor chip 18, the distance between the end face of the glass 20 and the center of the pad 19 indicated by symbol B in FIG. 16 is managed to be 125 μm or more.

  This distance is the minimum distance for preventing the capillary 22 and the glass 20 from coming into contact with each other when the first bond is made to the pad 19 of the semiconductor chip 18, and is not a distance that allows a reverse operation immediately above the pad 19. .

  The reverse operation immediately above the pad 19 is performed at a position where the capillary 22 is raised by about 150 μm from the point where it is lowered when the capillary 22 is first bonded. Assuming that the inclination angle of the outer peripheral surface of the capillary 22 is 10 degrees, there is a gap of 26 μm (= 150 × tan 10 °) in the horizontal direction, and accordingly horizontal operation is possible. However, the reverse operation is insufficient for the amount of about 150 μm, which is the same as the amount of increase, and it is not an amount that can bend the wire 23 even if the reverse operation is performed. It should be considered that the reverse operation at a height lower than the upper surface of the glass 20 is not possible. In addition, the numerical value shown here is not an absolute thing, and is an example to the last.

  Conventionally, for example, another semiconductor chip may exist on the semiconductor chip in a stack type package, but the presence of the upper semiconductor chip does not hinder the reverse operation in relation to the thickness and size. There was no idea of forming a good loop under conditions where the reverse operation was restricted.

Note that the basic loop formation concept of forming a trapezoidal loop by performing a reverse operation is disclosed in Patent Document 1. An example in which the direction in which the capillary first operates is the lead side is also disclosed in Patent Document 2.
Japanese Examined Patent Publication No. 6-101490 JP-A-2005-39192

  However, in the conventional wire bonding method described above, since the reverse operation cannot be performed, the loop shape cannot be controlled, and the shape variation becomes large. Also, since the allowable range for the amount of wire used to form a loop is narrow, if the amount of wire is too large, the wire will sag, and if it is too small, the wire will be pulled and broken to form a stable loop. There was a problem.

  The present invention solves the above-described problem, and since there is an object integrally provided at the upper center side of the semiconductor chip, even when the reverse operation for loop formation is restricted, the shape variation is small. An object of the present invention is to provide a wire bonding method capable of forming a stable loop with a wide allowable range for the amount of wire.

  In order to achieve the above object, according to a first wire bonding method of the present invention, between a first bond for bonding a wire to a pad of a semiconductor chip and a second bond for bonding a wire to a lead on a package side, The tip of the capillary that feeds out the wire passes through a bend forming point, and the bend forming point is in a straight line connecting the pad of the first bond and the lead of the second bond with respect to the pad as a reference. And is positioned higher than a member integrally provided on the upper portion of the semiconductor chip, and contact between the member and the wire before the tip of the capillary passes through the bending point It is characterized by happening.

  As a result, in the loop formed by connecting the pad of the first bond and the lead of the second bond, the bending formed on the side close to the pad affects the contact between the wire and the member on the semiconductor chip. The bend on the side close to the lead becomes a forced bend due to the reverse operation.

  In the second wire bonding method of the present invention, the tip of the capillary that feeds out the wire is between the first bond that bonds the wire to the pad of the semiconductor chip and the second bond that bonds the wire to the lead on the package side. The first and second bend forming points are passed, and the first bend forming point is in the linear direction connecting the pad of the first bond and the lead of the second bond, and the lead side with respect to the pad. And a lower direction than a member integrally provided on the upper portion of the semiconductor chip, and a second bending forming point connects the pad of the first bond and the lead of the second bond In this case, the semiconductor device is positioned on the center side of the semiconductor chip with respect to the pad and higher than the member provided on the semiconductor chip.

  Accordingly, in the loop formed by connecting the pad of the first bond and the lead of the second bond, the bending formed on the side close to the pad is caused by the movement of the capillary, and the bending on the side close to the lead is performed. Is forced to bend due to reverse motion.

  According to the third wire bonding method of the present invention, the tip of the capillary that feeds out the wire is between the first bond for bonding the wire to the pad of the semiconductor chip and the second bond for bonding the wire to the lead on the package side. The first and second bend forming points are routed, and the first bend forming point deviates from a straight line connecting the pad of the first bond and the lead of the second bond, and the upper portion of the semiconductor chip. The second bend formation point is located above the semiconductor chip and higher than the member provided on the semiconductor chip. .

  Accordingly, in the loop formed by connecting the pad of the first bond and the lead of the second bond, the bending formed on the side close to the pad is caused by the movement of the capillary, and the bending on the side close to the lead is performed. Is also caused by the movement of the capillary.

  As described above, according to the first wire bonding method of the present invention, the capillary passes through the bending point on the center side of the semiconductor chip at a height higher than the material integrally provided on the upper part of the semiconductor chip. A trapezoidal loop can be formed. That is, by bringing the wire and the member into contact with each other, an effect of moving downward the bending formed on the side close to the pad can be generated, and the height of the rising portion of the loop can be lowered. Furthermore, a forced bend can be intentionally formed on the side close to the lead to reduce variations in the loop shape, and the allowable range for the amount of wire used to form the loop can be widened.

  According to the second wire bonding method of the present invention, a trapezoidal loop can be formed through the first and second bending points. That is, the capillary can be bent to the side close to the pad by moving to the first bend forming point on the peripheral side of the semiconductor chip. This also allows the capillary to move to a second bending point that is higher than the member even under the condition that the wire and the member integrally provided on the upper part of the semiconductor chip are not brought into contact with each other. Thus, a trapezoidal loop can be formed. The height of the rising part of the loop can be controlled by bending the side closer to the pad, and the variation in the loop shape can be reduced by the two bendings, and the allowable range for the amount of wire used for forming the loop is widened. it can. Furthermore, even if the semiconductor chip moves to the bending point on the peripheral side of the semiconductor chip, the rising part of the pad side loop can be close to the normal vertical direction after the loop formation.

  Furthermore, according to the third wire bonding method of the present invention, the forcible bending is intentionally applied to the side close to the pad by moving to the first bending formation point in the vicinity of the pad, and the upper part of the semiconductor chip. By moving to the second bending point on the center side of the semiconductor chip at a height higher than that of the integrally provided member, a trapezoidal loop with intentionally forced bending near the lead is formed. be able to.

  The bend on the side close to the pad can control the height of the rising part of the loop in a wide range, and the variation in the loop shape can be reduced by the two bends, and the allowable range for the amount of wire used to form the loop is increased. Can be wide. At this time, by moving to the first bend formation point in the vicinity of the pad, the plane projection line of the loop bends and deviates from the straight line connecting the first bond and the second bond. If the second bend forming point is set on the opposite side of the first bend forming point via the straight line, the bent plane projection line can be returned and brought closer to the straight line.

(First embodiment)
A first embodiment for the purpose of the present invention will be described. The semiconductor device to which wire bonding is performed is the same as that described in the background art. The connection between the pad 19 and the lead 14 of the semiconductor device 11 by the wire bonding method of the first embodiment will be described with reference to FIGS.

  FIG. 1 is a side view showing a state of a semiconductor device before pad connection, FIG. 2 is a side view explaining reverse operation after pad connection, and FIG. 3 is a side view explaining rising to the highest point after reverse operation. 4 is a side view showing a state after the lead connection of the semiconductor device.

  1 to 4, reference numeral 22 denotes a capillary used for wire bonding, which has a cylindrical shape and a wire 23 is passed through the capillary. Reference numeral 24 denotes a wire clamper provided on the upper part of the capillary 22, which operates integrally with the capillary 22 and controls the relative movement of the wire 23 relative to the capillary 22 by opening and closing thereof.

As will be described below, the wire bonding is performed while the ceramic package 12 on which the semiconductor chip 18 is mounted is pressed and fixed on the apparatus and heated.
In the wire bonding, as shown in FIG. 1, with the wire clamper 24 closed, an initial ball 25 is formed by discharge on the tip of the wire 23 coming out of the tip of the capillary 22.

  Next, the wire clamper 24 is opened, and as shown in FIG. 2, a first bond that presses the initial ball 25 against the pad 19 of the semiconductor chip 18 and joins one end of the wire 23 to the pad 19 by the action of heat and ultrasonic waves. Do. After that, the capillary 22 moves upward while feeding the wire 23, and when the center of the lower surface of the capillary 22 reaches the point C shown in FIG. 2, the operation direction is changed to the horizontal direction. Reverse operation is performed up to point D on the glass 20.

  This point D is a bend forming point, considering the relative positional variation between the wire 23 and the glass 20, satisfying the condition that the wire 23 and the glass 20 are always in contact with each other, and intentionally attaching to the wire 23. This is a point set at a position far from the lead 14 so that forced bending can be applied.

At point D, the wire 23 is bent in contact with the glass 20 and the wire 23 has an angle with respect to the capillary 22, so that the wire 23 can be bent.
At this time, since the wire clamper 24 is in an open state, even if the wire 23 and the glass 20 come into contact with each other, the wire 23 is only drawn out, and the wire 23 is not forcibly pulled and a problem occurs. do not do.

  Thereafter, as shown in FIG. 3 and FIG. 4, the capillary 22 rises again vertically to reach the uppermost point and then descends in an arc shape toward the lead 14 to which the other end of the wire 23 is connected. To form a loop. Then, a second bond is performed in which the wire 23 is pressed against the lead 14 to join the other end of the wire 23 to the lead 14.

  The loop formed by the above-described operation has a shape in which the bend on the side close to the pad 19 is affected by the contact between the wire 23 and the glass 20, but the bend on the side close to the lead 14 is affected by the reverse operation, that is, the glass. The shape is strongly influenced by the movement in the horizontal direction from 20 to the position far from the lead 14, and a trapezoidal loop as a whole.

  That is, the deformed portion formed by the contact between the wire 23 and the glass 20 becomes a recess at a position away from the rising portion of the loop after the loop is formed. This affects the bending position on the side closer to the pad 19 to move downward, and the height of the rising portion of the loop is lowered.

  Thereafter, the capillary 22 rises, and the wire clamper 24 is closed in the middle of the rise, thereby disabling relative movement of the wire 23 with respect to the capillary 22 and tearing the wire 23. At this time, the wire 23 comes out from the tip of the capillary 22 in the same state as the beginning.

Next, the operations described above are repeated to sequentially connect the pads 19 of the semiconductor chip 18 and the leads 14 of the ceramic package 12.
As described above, in the first embodiment, although the reverse operation is not performed at a height lower than the upper surface of the glass 20, the reverse operation is performed at a height higher than the glass 20, so that the loop is bent at two locations, that is, the pad. Bending near 19 and bending near lead 14 can be applied. That is, the wire 23 and the glass 20 are brought into contact with each other so as to move the bending forming position closer to the pad 19 downward, so that the height of the rising portion of the loop is lowered. In addition, the variation in the loop shape can be reduced by intentionally bending the loop closer to the lead 14 and forming a forced bend with a large bending angle instead of the natural bent shape as in the prior art.

  For this reason, the allowable range of the amount of wire used to form the loop is widened, the wire does not drip even if the amount of wire is too large, and the wire is not pulled and broken even if it is too small, A stable loop can be formed.

  In the first embodiment, the reverse operation is performed horizontally from the point C to the point D shown in FIG. 2, but the movement path from the pad 19 to the point D can be variously changed. For example, after the tip of the capillary 22 rises to the same height as the glass 20, it may move diagonally and move to point D, or it moves in an arc shape from a position higher than point C and moves to point D. May be.

  In addition, from point D, the arc descends toward the lead 14 after reaching the highest point in the vertical direction, but the movement route can be variously changed. For example, in order to apply a strong bend with a larger bending angle, it may be lowered and then tilted up to the uppermost point, or may be moved in a horizontal direction from the uppermost point toward the lead 14 and then arc-shaped toward the lead 14. A descending operation may be performed.

The main point of the present embodiment is only one reverse operation performed at a height higher than the upper surface of the glass 20, and the contact between the wire 23 and the glass 20 affects the bending on the side close to the pad 19, and the lead 14. The trapezoidal loop is formed by intentionally forcing the bend on the side close to 曲 げ.
(Second Embodiment)
A second embodiment of the present invention will be described. The semiconductor device to which wire bonding is performed is the same as that described in the background art. The semiconductor device to which wire bonding is performed is the same as that described in the background art. The connection between the pad 19 and the lead 14 of the semiconductor device 11 by the wire bonding method of the second embodiment will be described with reference to FIGS.

  FIG. 5 is a side view showing a state before the pad connection of the semiconductor device, FIG. 6 is a side view explaining the operation in the lead direction after the pad connection, and FIG. 7 is a side view explaining the reverse operation after the operation in the lead direction. 8 is a side view for explaining the rise to the highest point after the reverse operation, and FIG. 9 is a side view showing a state after the lead connection of the semiconductor device.

  In FIGS. 5 to 9, reference numeral 22 denotes a capillary used for wire bonding, in which a capillary is formed and a wire 23 is passed therethrough. Reference numeral 24 denotes a wire clamper provided on the upper part of the capillary 22, which operates integrally with the capillary 22 and controls the relative movement of the wire 23 relative to the capillary 22 by opening and closing thereof.

As will be described below, the wire bonding is performed while the ceramic package 12 on which the semiconductor chip 18 is mounted is pressed and fixed on the apparatus and heated.
In the wire bonding, as shown in FIG. 5, with the wire clamper 24 closed, an initial ball 25 is formed by discharge on the tip of the wire 23 protruding from the tip of the capillary 22.

  Next, the wire clamper 24 is opened, and as shown in FIG. 6, a first bond that presses the initial ball 25 against the pad 19 of the semiconductor chip 18 and joins one end of the wire 23 to the pad 19 by the action of heat and ultrasonic waves. Do. Thereafter, the capillary 22 slightly rises while feeding the wire 23, and after the center of the lower surface of the capillary 22 reaches point E at a height lower than the upper surface of the glass 20 shown in FIG. Then, the movement to the point F in the direction of the lead 14 is performed. Since the wire 23 has an angle with respect to the capillary 22 at the point F forming the first bending formation point, the wire 23 can be bent.

  At the point F, the tip of the capillary 22 is lower than the glass 20 but does not cause a problem of interference because it moves away from the glass 20. However, when it is set at a position far from the pad 19, the loop after the formation is completed Since it falls too far to the side, it should be set to a position where a slight bend can be applied.

  Thereafter, as shown in FIG. 7, the capillary 22 moves upward while feeding the wire 23, and after the center of the lower surface of the capillary 22 reaches the point G shown in FIG. 7, the direction of operation is changed horizontally to reverse the lead 14. Reverse operation is performed up to point H on the glass 20 in the direction.

  Since the wire 23 has an angle with respect to the capillary 22 at the point H forming the second bending formation point, the wire 23 can be bent. At the point H, the problem of interference between the capillary 22 and the glass 20 does not occur because the capillary 22 is positioned higher than the glass 20. In addition, the wire 23 is bent in a shape that slows the contact with the glass 20 when the reverse operation is performed because it passes through the point F. For this reason, even if the wire 23 and the glass 20 are not brought into contact with each other, the point H can be set at a position far from the lead 14, so that the wire 23 can be strongly bent.

  Further, as shown in FIG. 7, when the wire 23 moves to the point H, the wire 23 has an angle with respect to the capillary 22 and falls to the opposite side to the lead 14, so that the rising portion of the loop is in a natural direction after the loop is formed. It becomes the state which is near the perpendicular which is.

  Thereafter, as shown in FIG. 8, the capillary 22 rises vertically again to reach the uppermost point, and then performs an arc-shaped descending operation toward the lead 14 to which the other end of the wire 23 is connected. To form a loop.

  Thereafter, as shown in FIG. 9, a second bond is performed in which the wire 23 is pressed against the lead 14 and the other end of the wire 23 is joined to the lead 14. The loop formed thereby has a shape influenced by the fact that the bend on the side close to the pad 19 is moved in the reverse direction to the reverse operation when initially raised, and the bend on the side close to the lead 14 is affected by the reverse operation. The shape is strongly influenced by the horizontal movement from the lead 14 to a position far from the lead 14 above the glass 20, and a trapezoidal loop as a whole. By passing through the point F, after the loop is formed, a dent-like trace is formed on the upper surface of the wire 23 at the rising portion of the loop on the pad 19 side, but this is not a problem because it is not related to damage.

  Thereafter, the capillary 22 rises, and the wire clamper 24 is closed in the middle of the rise, thereby disabling the relative movement of the wire 23 with respect to the capillary 22 and tearing the wire 23. As a result, the wire 23 comes out from the tip of the capillary 22 as in the beginning.

At this time, the wire 23 comes out from the tip of the capillary 22 in the same state as the beginning.
Next, the operations described above are repeated to sequentially connect the pads 19 of the semiconductor chip 18 and the leads 14 of the ceramic package 12.

  Thus, in the second embodiment, the loop can be bent on the side closer to the pad 19 by operating the capillary 22 in a direction opposite to the reverse operation at a height lower than the upper surface of the glass 20. This bending is due to the operation of the capillary 22, and the height of the rising portion of the loop can be controlled by adjusting the moving distance from the pad 19 and changing the bending position. Further, by operating the capillary 22 in a direction opposite to the reverse operation prior to the reverse operation, the reverse operation performed at a height higher than the upper surface of the glass 20 is large even under the condition that the wire 23 and the glass 20 are not in contact with each other. The reverse operation can be performed, and the bent shape on the side close to the lead 14 of the loop is intentionally a forced bend with a large bending angle, and the variation in the loop shape can be reduced by the two bends to form a loop. The allowable range for the amount of wire used can be widened, and even when the amount of wire is too large, the wire does not hang down, and when it is too small, the wire is not pulled and broken, and a stable loop can be formed.

  In the second embodiment, the operation is performed in the direction of the lead 14 from the point E to the point F shown in FIG. 6, but the movement path from the pad 19 to the point F can be variously changed. . For example, the capillary 22 may be moved obliquely from the pad 19 to the point F, or may be moved in an arc shape from a position higher than the point E to the point F. Similarly, although the reverse operation is performed in the horizontal direction from the point G to the point H shown in FIG. 7, the path of movement from the point F to the point H can be variously changed. In addition, from the point H, it is assumed that the arc descending operation is performed toward the lead 14 after ascending vertically and reaching the uppermost point. However, various movement paths can be changed.

The main point of the present embodiment is that an intentional bending is performed on the side closer to the pad 19 by performing an operation of bending in a direction opposite to the reverse operation at a position lower than the upper surface of the glass 20, thereby This makes it possible to increase the reverse movement of the trapezoidal loop, and to form a trapezoidal loop with intentionally forced bending on the side close to the lead 14.
(Third embodiment)
Next, a third embodiment of the present invention will be described. The semiconductor device to which wire bonding is performed is the same as that described in the background art. The connection between the pad 19 and the lead 14 of the semiconductor device 11 by the wire bonding method of the third embodiment will be described with reference to FIGS.

  10 is a side view showing a state of the semiconductor device before pad connection, FIG. 11 is a side view for explaining the operation of the semiconductor chip in the side direction after pad connection, and FIG. 12 is the side view of the semiconductor chip after operation in the side direction. FIG. 13 is a side view for explaining the operation in the direction reverse to the side direction and away from the lead, and FIG. 13 is a side view for explaining the rise to the highest point after the operation in the direction reverse to the side direction and away from the lead. FIG. 3 is a side view showing a state after lead connection of a semiconductor device.

  10 to 14, reference numeral 22 denotes a capillary used for wire bonding, which has a cylindrical shape and a wire 23 is passed through the capillary. Reference numeral 24 denotes a wire clamper provided on the upper part of the capillary 22, which operates integrally with the capillary 22 and controls the relative movement of the wire 23 relative to the capillary 22 by opening and closing thereof.

As will be described below, the wire bonding is performed while the ceramic package 12 on which the semiconductor chip 18 is mounted is pressed and fixed on the apparatus and heated.
In the wire bonding, as shown in FIG. 10, with the wire clamper 24 closed, an initial ball 25 is formed on the tip of the wire 23 protruding from the tip of the capillary 22 by discharge.

  Next, the wire clamper 24 is opened, and as shown in FIG. 11, a first bond that presses the initial ball 25 against the pad 19 of the semiconductor chip 18 and joins one end of the wire 23 to the pad 19 by the action of heat and ultrasonic waves. Do. After that, the capillary 22 slightly rises while feeding the wire 23, and after the center of the lower surface of the capillary 22 reaches a point J having a height less than the upper surface of the glass 20 shown in FIG. The movement to the point K in the direction along one side is performed.

  Since the wire 23 has an angle with respect to the capillary 22 at the point K forming the first bending formation point, the wire 23 can be bent. In the movement to the point K, the tip of the capillary 22 moves to a position lower than the glass 20, but the movement of the capillary 22 is almost parallel to the end face of the glass 20, so that the problem of interference does not occur. However, if the point K is too close to the pad 19, the bending does not occur. If the point K is too far, the bending angle becomes too sharp, and the loop projection line of the loop deviates from the straight line connecting the pad 19 and the lead 14. Therefore, it should be set in the middle.

  Thereafter, as shown in FIG. 12, the capillary 22 moves upward while feeding the wire 23, and after the center of the lower surface of the capillary 22 reaches the point L shown in FIG. The movement to the point M on the glass 20 in the direction of moving away is performed. The point M and the point K are located on opposite sides of the line connecting the pad 19 and the lead 14, and the distance that the point M is separated from the line connecting the pad 19 and the lead 14 is such that the point K is the pad 19 and the lead. 14 is equal to the distance away from the straight line connecting 14. The reason for setting the M point at such a position is to return the curve of the loop projection line of the loop that occurs via the K point, and to bring the loop projection line of the loop closer to the straight line connecting the pad 19 and the lead 14. is there.

Since the wire 23 has an angle with respect to the capillary 22 at the point M forming the second bending formation point, the wire 23 can be bent.
Thereafter, as shown in FIG. 13, the capillary 22 rises vertically again to reach the uppermost point, and then performs an arc-shaped descending operation toward the lead 14 to which the other end of the wire 23 is connected. To form a loop.

  Thereafter, as shown in FIG. 14, a second bond is performed in which the wire 23 is pressed against the lead 14 to join the other end of the wire 23 to the lead 14. The loop formed by this is because the bending near the pad 19 is not a reverse operation but the bending operation is performed, and the bending near the lead 14 is above the glass 20 and the capillary 22 is reversed. As a whole, it becomes a trapezoidal loop. At this time, if the movement direction is devised, it is possible to correct the curve of the loop projection line of the loop and return it to a straight line due to the first bending operation.

Thereafter, the capillary 22 rises, and the wire clamper 24 is closed in the middle of the rise, thereby disabling the relative movement of the wire 23 with respect to the capillary 22 and tearing the wire 23.
At this time, the wire 23 comes out from the tip of the capillary 22 in the same state as the beginning.

Next, the operations described above are repeated to sequentially connect the pads 19 of the semiconductor chip 18 and the leads 14 of the ceramic package 12.
As described above, in the third embodiment, the capillary 22 is operated in a direction deviating from the straight line connecting the pad 19 and the lead 14 at a height lower than the upper surface of the glass 20, so that the loop is bent closer to the pad 19. Can be attached. At this time, the height of the rising portion of the loop can be controlled in a wide range by changing the bending position according to the distance at which the capillary 22 is separated from the pad 19.

  Then, the capillary 22 can be operated above the height of the upper surface of the glass 20 to bend the lead 14. By these two bends, the variation in the loop shape can be reduced, and the allowable range for the amount of wire used to form the loop can be widened.

  In the third embodiment, the point K shown in FIG. 11 is set as a point parallel to one side of the semiconductor chip 18, but does not interfere with the glass 20 and connects the pad 19 and the lead 14. Various changes can be made as long as the condition of deviating from the straight line is satisfied. For example, the capillary 22 may be a point slightly inward of the semiconductor chip 18 or may be a point away from the semiconductor chip 18.

  Further, the position of point M shown in FIG. 12 can be variously changed. Even if the plane projection line is bent, if the capillary 22 does not hit the wire 23 when connecting the next wire 23 and there is no damage due to excessive force applied to the wire 23, for example, a pad 19 may be on a straight line connecting the lead 14 and may be on the same side as the point K with respect to the straight line connecting the pad 19 and the lead 14.

  Further, although the operation of moving horizontally from the point J to the point K shown in FIG. 11 in the direction of the lead 14 is performed, the path of movement from the pad 19 to the point K can be variously changed. Similarly, the reverse operation is performed horizontally from the L point to the M point shown in FIG. 12, but the movement path from the L point to the M point can be variously changed. Further, from the point M, it is assumed that the arc descending operation is performed toward the lead 14 after vertically rising to reach the uppermost point. However, the movement route can be variously changed.

  The main point of the present embodiment is that it is intentionally forced on the side close to the pad 19 by performing an operation of bending in a direction deviating from a straight line connecting the pad 19 and the lead 14 at a height lower than the upper surface of the glass 20. In other words, a trapezoidal loop is formed by intentionally and forcibly bending the side close to the lead 14 by an operation of bending the glass 20 at a height higher than the upper surface of the next glass 20.

  In the first to third embodiments, it has been described that the semiconductor device 11 uses the ceramic package 12. However, the present invention can be applied not only to the ceramic package 12 but also to other packages. Further, the glass 20 has been described as being integrally provided on the semiconductor chip 18. However, the present invention is not limited to the glass 20 and can be applied to a case where there is an object that hinders the reverse operation. Furthermore, although the trapezoidal loop is formed, a multistage trapezoidal loop having a larger number of bent portions may be used.

  The wire bonding method of the present invention is useful as a wire bonding method capable of forming a stable loop even when there is an object integrally provided at the upper part on the semiconductor chip center side.

The side view showing the state before pad connection among the connection by wire bonding in the 1st Embodiment of this invention Side view explaining reverse operation after pad connection among connections by wire bonding in the embodiment The side view explaining the rise to the highest point after reverse operation among the connection by wire bonding in the embodiment The side view showing the state after lead connection among the connection by wire bonding in the embodiment The side view showing the state before pad connection among the connection by wire bonding in the 2nd Embodiment of this invention The side view explaining the operation | movement to the lead direction after pad connection among the connections by wire bonding in the said 2nd Embodiment Side view explaining reverse operation after operation in lead direction among connections by wire bonding in the second embodiment The side view explaining the rise to the highest point after reverse operation among the connections by wire bonding in the second embodiment Side view showing a state after lead connection among connections by wire bonding in the second embodiment The side view showing the state before pad connection among the connection by wire bonding in the 3rd Embodiment of this invention The side view explaining the operation | movement to the side direction of the semiconductor chip after pad connection among the connection by wire bonding in the same 3rd Embodiment The side view explaining the operation | movement to the direction opposite to the side direction after operation | movement to the side direction of a semiconductor chip and away from a lead | read | reed among the connections by wire bonding in the said 3rd Embodiment The side view explaining the rise to the highest point after the operation | movement to the direction which is reverse to a side direction and away from a lead among the connection by wire bonding in the said 3rd Embodiment Side view showing a state after lead connection among connections by wire bonding in the third embodiment Perspective view before wire bonding during manufacturing of semiconductor device Side view before wire bonding during semiconductor device manufacturing Side view showing the state prior to pad connection among conventional wire bonding connections Side view showing the state at the time of pad connection among conventional wire bonding connections Side view explaining the rise to the highest point after pad connection in conventional wire bonding connection Side view showing the state after lead connection among conventional wire bonding connections

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Semiconductor device 12 Ceramic package 13 Die pad 14 Lead 15 Side wall 16 External terminal 17 Adhesive paste 18 Semiconductor chip 19 Pad 20 Glass 21 Adhesive 22 Capillary 23 Wire 24 Wire clamper 25 Initial ball

Claims (3)

Between the first bond that joins the wire to the pad of the semiconductor chip and the second bond that joins the wire to the lead on the package side, the tip of the capillary that feeds out the wire goes through a bending point, A bending point is located on the center side of the semiconductor chip with respect to the pad in a linear direction connecting the pad of the first bond and the lead of the second bond, and is provided integrally on the upper part of the semiconductor chip. A wire bonding method, wherein the contact between the member and the wire occurs before the tip of the capillary passes through the bending point. Between the first bond for bonding the wire to the pad of the semiconductor chip and the second bond for bonding the wire to the lead on the package side, the tip of the capillary that feeds the wire passes through the first and second bending points. A first bend forming point is located on the lead side with respect to the pad in a linear direction connecting the pad of the first bond and the lead of the second bond, and on the upper portion of the semiconductor chip. The second bending forming point is located on the center side of the semiconductor chip with respect to the pad in the linear direction connecting the pad of the first bond and the lead of the second bond. And a position higher than the member provided on the semiconductor chip. Between the first bond for bonding the wire to the pad of the semiconductor chip and the second bond for bonding the wire to the lead on the package side, the tip of the capillary that feeds the wire passes through the first and second bending points. The first bend formation point is located off the straight line connecting the pad of the first bond and the lead of the second bond and lower than a member integrally provided on the upper part of the semiconductor chip. The wire bonding method is characterized in that the second bending point is located above the semiconductor chip and higher than the member provided on the semiconductor chip.

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