JP2007311653A - Solder coating method, solder coating unit, and die bonder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solder coating unit excellent in workability and quality of solder application, and a die bonder. <P>SOLUTION: While a first point P1 of a substrate 1' is stopped just below a solder wire 2 supported by a solder supply unit 4, the solder wire 2 is let out down below at a constant speed so that the end of the wire is brought in contact and melted with the first point P1. In succession, the whole solder supply unit 4 is horizontally moved in a direction parallel to the coated surface of the substrate 1' by a drive control system 20 to successively melt the solder wire 2 bit by bit from its end on the substrate 1', and the melted solder 2d is applied to the coated surface of the substrate 1' in a horizontal and approximately elliptical shape. If the solder wire 2 is moved as far as a second point P2, the solder wire 2 is pulled up to finalize the one-stroke solder application operation on the substrate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solder application method for applying a certain amount of solder to a lead frame, a solder application unit, and a die bonder for soldering a semiconductor chip to a lead frame using this solder application method / unit.

  A die bonder, which is a semiconductor manufacturing facility, supplies a predetermined amount of solder to a plurality of islands of a lead frame and melts them in order, and mounts a semiconductor chip on the melted solder. This die bonder uses a heater rail that intermittently conveys the lead frame in the horizontal direction in a non-oxidizing atmosphere while preheating the lead frame to the solder melting point or higher (see, for example, Patent Document 1). The heater rail is a horizontal rail that is long in the lead frame transport direction, and has a tunnel-like lead frame transport path maintained in a non-oxidizing atmosphere. A solder application position, a solder shaping position, and a chip supply position are continuously arranged in the lead frame conveyance path, and islands of the lead frame are intermittently conveyed in order to each position. When one island is brought into the solder application position and stopped by the intermittent conveyance of the lead frame, a certain amount of solder is supplied to the surface to be applied, which is a predetermined area area on the island, by the solder application unit installed at the position, Melts with island preheating. When the island is intermittently conveyed to the next solder shaping position, the molten solder on the island is shaped according to the shape of the semiconductor chip by the solder shaping unit installed at the same position. When the island is intermittently conveyed to the next chip supply position, the semiconductor chip is mounted on the molten solder shaped by the chip supply unit installed at the same position.

  A known solder application unit that applies a certain amount of solder to an island of a lead frame uses a solder supply device that feeds a solder wire in a wire axial direction with a feed roller or the like (see, for example, Patent Document 2). This solder supply device applies a certain amount of solder to the island by feeding the solder wire from the wire supply nozzle in the axial direction, bringing the tip of the wire into contact with the preheated island and melting it in a dot shape. The solder is applied to one or a plurality of locations on the surface to be coated, depending on the area of the surface to be coated on which the solder of the island is applied. For example, FIG. 9 and FIG. 10 describe a solder application method and a solder application unit in which solder is applied in two dots on the surface to be applied.

  The heater rail 5 shown in FIG. 9 holds the lead frame 1 horizontally and intermittently conveys it in the longitudinal direction. The lead frame 1 is a flat plate elongated in the lead frame conveyance direction, and has a plurality of islands 1 ′ on which the semiconductor chips 3 are mounted at equal intervals. The island 1 'is a metal substrate having an area larger than that of the semiconductor chip 3, and is hereinafter referred to as a substrate 1' as necessary. The heater rail 5 has a tunnel-like lead frame conveyance path 7 closed by a cover plate 6. The lead frame transport path 7 is maintained in a non-oxidizing atmosphere by blowing an antioxidant gas such as nitrogen gas. The heater rail 5 is preheated to an appropriate temperature above the solder melting point by a heater (not shown). A plurality of, for example, three work openings 8a to 8c formed in the cover plate 6 are a solder application opening 8a, a solder stirring shaping opening 8b, and a chip supply opening 8c from the upstream side in the lead frame conveying direction. A solder application unit U1, a solder shaping unit U2, and a chip supply unit U3 are installed at the positions of the respective work openings 8a to 8c.

  The solder application unit U1 shown in FIGS. 9 and 10 includes a solder supply device 4 that holds the solder wire 2 and feeds it in the wire axial direction. The solder supply device 4 includes a pair of feed rollers 9 and 10 that sandwich the solder wire 2 and apply an axial feed, a roller drive control device 11 that rotates the feed rollers 9 and 10 forward and backward, and a tip portion of the solder wire 2. A supply nozzle 12 for guiding the above is provided. The solder supply device 4 is supported by an XY table (not shown) and freely moves in the horizontal XY direction. The solder application unit U1 includes a solder supply device 4 and an XY table.

  When the lead frame 1 is intermittently conveyed once and one substrate 1 ′ is carried directly under the solder application opening 8 a, the solder wire 2 is drawn out from the supply nozzle 12 waiting at the chain line position in FIG. 9. . Wire feeding is performed by forward rotation of the pair of feed rollers 9 and 10. The tip (lower end) of the drawn-out solder wire 2 comes into contact with one point on the surface to be coated of the substrate 1 ′ and is melted by preheating the substrate 1 ′. When the solder wire 2 is fed out in a fixed amount, the feed rollers 9 and 10 are reversely rotated to pull up the solder wire 2 to the supply nozzle 12 side with a constant stroke, and at the first point on the substrate 1 ′, molten solder is formed in a dot shape. 2a is applied. Next, the solder supply device 4 moves horizontally to the solid line position in FIG. 9 and stops. At this solid line position, the feed rollers 9 and 10 again rotate forward to feed the solder wire 2 straight down, and separate the substrate 1 ′. The tip of the solder wire 2 is brought into contact with one point and melted. The feed rollers 9 and 10 again rotate reversely to pull up the solder wire 2 and apply the molten solder 2b in the form of dots at the second point on the substrate 1 '(see FIG. 11).

  When the substrate 1 ′, which has been subjected to solder application by intermittent conveyance of the lead frame 1, is conveyed and stopped immediately below the next solder agitation shaping opening 8 b, the agitation tool 13 of the solder shaping unit U 2 descends the opening 8 b, The work (tapping work) for pressing and spreading the two molten solders 2 a and 2 b on the substrate 1 ′ flatly is performed and shaped into a shape similar to that of the semiconductor chip 3. The lower end of the stirring tool 13 is a concave surface that matches the shape of the semiconductor chip 3, and the molten solder 2 a and 2 b at two locations are simultaneously pressed by this concave surface to shape the molten solder 2 c with an equal thickness (see FIG. 12).

When the substrate 1 ′ that has undergone solder shaping by the solder shaping unit U <b> 2 is conveyed and stopped immediately below the next chip supply opening 8 c, the chip supply tool 14 of the chip supply unit U <b> 3 is in a state where the semiconductor chip 3 is vacuum-sucked. The opening 8c is lowered. When the adsorbed semiconductor chip 3 is mounted on the molten solder 2c on the substrate 1 ′, the chip supply tool 14 is lifted by releasing the vacuum suction, and die bonding of one semiconductor chip is completed.
Japanese Unexamined Patent Publication No. 2000-232114 (FIG. 1) Japanese Patent No. 2826193

  As shown in FIG. 11, when the molten solders 2 a and 2 b are applied to two spaced points on the substrate 1 ′, the molten solders 2 a and 2 b spread concentrically and are applied in a substantially circular shape. At this time, segregation of the molten solder may occur on the lower peripheral surface portions of the molten solders 2a and 2b (interface portions with the substrate 1 '), and voids may be generated. When the two molten solders 2a and 2b melted at two points separated from each other are spread out like the molten solder 2c in FIG. 12, a void 30 as shown in FIG. 13 is formed between the substrate 1 ′ and the molten solder 2c. May occur. FIG. 13 conceptually shows an X-ray projection of the molten solder 2c in FIG. The generation of voids 30 is frequent at the peripheral portion of the first molten solder 2a where segregation proceeds while the second molten solder 2b is applied. Such a void 30 is generated almost at the center of the shaped molten solder 2c, affects the mountability and bonding quality of the semiconductor chip 3, and it is difficult to reduce the generation of voids.

  In addition, in the solder application operation on the substrate 1 ′, it is difficult to accurately adjust the positions of the two points as the solder wire supply points and to control the solder supply amounts at the two points to the same amount. Therefore, the amount and shape of the molten solders 2a and 2b at the two points are likely to vary. In particular, if the distance between the two solder application points on the substrate 1 ′ is short, when the second molten solder 2 b is applied, the molten solder 2 b contacts the first molten solder 2 a previously applied. There are things to do. When the second molten solder 2b comes into contact with the first molten solder 2a in this way, the second molten solder 2b flows into the first molten solder 2a side from the contact portion, and the two molten solders 2a, 2b The amount of application is different, and the shape is deformed. Therefore, the shape and thickness of the molten solder 2c formed by pressing the two molten solders 2a and 2b with the stirring tool 13 are unstable, and the semiconductor chip 3 is inclined when the semiconductor chip 3 is mounted. A mounting failure may occur.

  Further, since the solder wire 2 is moved up and down at two points on the substrate 1 ', the index of one solder application is slow and it is difficult to increase the speed. The area of the surface to be coated of the substrate 1 ′ is large, and the index becomes slower as the number of points to be applied increases by two or three points, which makes it difficult to improve the index of the die bonder.

  An object of the present invention is to provide a solder coating method excellent in workability and quality of solder coating, a solder coating unit suitable for this solder coating method, and a die bonder.

  The solder coating method that achieves the above-mentioned object of the present invention is to quantitatively apply to the coated surface by bringing the coated surface of the substrate preheated to the solder melting point or more into contact with the tip of the solder wire fed from the solder supply device and melting it. A solder application method for applying a solder, wherein a solder wire is fed from a solder supply device to a first location of a first location and a second location that are separated from the surface to be coated, and the tip of the wire is brought into contact with and melted. Then, the solder wire is relatively moved in the direction parallel to the coated surface to the second location on the coated surface, and the solder is continuously applied from the first location to the second location on the coated surface.

  Here, the substrate is preheated to a temperature that melts the solder wire that is in contact with a metal plate such as an island of the lead frame or a heat sink integrated with the lead frame. Two spaced apart points provided on the surface to be coated, which is a predetermined area on the substrate, are defined as a first location and a second location. The solder wire is applied in a single stroke while continuously melting the solder wire from the first location to the second location on the surface to be coated, so that the solder is applied in an average amount over almost the entire surface to be coated. One stroke writing here is desirable to accurately control the coating operation with a straight line of the shortest distance between the first place and the second place, but quadratic writing such as arc writing and U-shaped writing is also effective. It is. By applying a fixed amount of solder by moving the solder wire relative to the coated surface of the substrate in a single stroke, the molten solder is not dispersed at a plurality of points on the coated surface. Even if segregation occurs in one molten solder and voids are generated, the voids are concentrated on the peripheral edge of the molten solder, and there is less concern about affecting the bonding quality of the semiconductor chip. In addition, if one molten solder applied to the substrate is shaped with a stirring tool, the shape is stabilized and the mountability of the semiconductor chip is improved. Furthermore, one molten solder applied to the substrate is shaped with the stirring tool. Without this, the semiconductor chip can be mounted directly on the molten solder.

  In the present invention, the solder wire is fed out from the solder supply device at a constant speed, and the relative movement speed of the solder wire from the first position to the second position with respect to the coated surface of the substrate is variably controlled so as to be non-constant. Can do.

  That is, when the solder wire is relatively moved at a constant speed from the first location to the second location on the board, the first location and If variably controlled so as to temporarily lower the relative movement speed at the intermediate portion of the second location, the amount of application at the intermediate portion increases and the solder can be applied on the surface to be coated on average.

  In the present invention, the lead wire in which the substrate is intermittently conveyed in a substantially horizontal direction can be moved relative to the lead frame when the lead frame is stopped after conveyance. Alternatively, in the lead frame in which the substrate is intermittently transported in a substantially horizontal direction, when the lead frame is transported, the solder wire fed from the solder supply device at a fixed position toward the lead frame may be moved relative to the lead frame. it can.

  The substrate in this case is a lead frame island. When the lead frame is intermittently conveyed while preheating with a heater rail, etc., and one island (substrate) is loaded into the solder application position where the solder wire is waiting, the island is stopped and the solder wire is moved to the island. Move relative. In this coating method, the solder coating unit is movably disposed on the left and right and is moved relative to the stopped lead frame. Alternatively, the solder wire is moved relative to the island using the lead frame transport operation when the island is carried into the solder application position or when the island is carried out of the solder application position. In this case, the solder wire in the solder application unit only needs to be moved up and down once with respect to the island moving left and right. When the solder wire is moved up and down once during the intermittent conveyance of the lead frame and a certain amount of solder is applied to the surface to be coated, the solder application operation ends when the single intermittent conveyance of the lead frame is completed. Accordingly, immediately after the lead frame is intermittently conveyed, the molten solder immediately after being applied to the island can be shaped with the stirring tool, or the semiconductor chip can be mounted on the molten solder immediately after being applied to the island with the chip supply tool.

  The solder coating unit of the present invention melts the tip of the solder wire fed from the solder supply device in contact with a predetermined coated surface of the lead frame that is preheated to a melting point of the solder and intermittently conveyed in a substantially horizontal direction. A solder application unit for applying a certain amount of solder to the surface to be applied, wherein the solder wire is supplied from the solder supply device to the first and second locations separated on the surface to be applied of the lead frame. While the tip is melted, the solder wire is moved relative to the second surface of the coated surface in a direction parallel to the coated surface to continuously solder the first to second portions of the coated surface. And a drive control system for moving both the solder supply device and the lead frame relative to each other so as to apply the solder.

  As the drive control system here, computer software incorporated in an X control system and a Y control system of a horizontal XY table that supports the entire solder supply apparatus is effective.

  Further, the die bonder of the present invention melts the tip of the solder wire fed out from the solder supply device in contact with a predetermined coated surface of the lead frame that is preheated to the melting point of the solder and intermittently conveyed in a substantially horizontal direction. A die bonder comprising a solder application unit for applying a fixed amount of solder to the surface to be applied, and a chip supply unit for mounting a semiconductor chip on the molten solder on the surface to be applied applied by the solder application unit. The unit is configured such that the solder wire is fed from the solder supply device to the first part of the first part and the second part, which are provided on the coated surface of the lead frame, and the tip is brought into contact with the first part to melt the solder. In order to apply the solder continuously from the first part to the second part of the coated surface by relatively moving the wire to the second part of the coated surface in a direction parallel to the coated surface. Characterized by comprising a drive control system for relatively moving both the supply device and the lead frame.

  In the die bonder of the present invention, the molten solder on the surface to be coated of the substrate coated by the solder coating unit is pressed and stirred by the flat pressing surface of the stirring tool before mounting the semiconductor chip by the chip supply unit. It can be set as the structure provided with the solder shaping unit to shape.

  According to the solder application method of the present invention, since a fixed amount of solder is applied by moving the tip of a solder wire relative to one application surface of a substrate such as a lead frame in a single stroke, the entire surface is applied to the application surface of the substrate. A single molten solder that does not disperse in an average amount can be applied. Since such single molten solder application can be performed by only one up and down movement of the solder wire, the index is fast and the application time can be shortened. By shortening this time, segregation hardly occurs in the molten solder during solder application, and void generation due to segregation is reduced. In addition, solder is applied continuously by moving the solder wire relative to the second part from the first part to the second part of the predetermined application surface of the substrate, so that it is applied to each of two separate points on the application surface. In addition, there is no trouble that the two molten solders come into contact with each other during the application operation and the shape is deformed, so that the solder can be applied in a stable shape at all times, and the solder application performance can be improved.

  In addition, in the case of a die bonder that mounts a semiconductor chip by shaping the molten solder applied to the substrate, even if a void occurs in the peripheral portion of the molten solder applied to the substrate, the void is formed in the central portion of the molten solder. It is less likely to occur and the mountability of the semiconductor chip mounted on the molten solder can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIGS. 1A to 1D are for explaining the solder coating method of the present invention applied to the solder coating unit U1 in the die bonder of FIGS. 1 to 8, parts that are basically the same as those in FIGS. 9 and 10 are given the same reference numerals to avoid duplication of explanation.

  A substrate 1 ′ shown in FIG. 1 schematically shows an island of the lead frame 1 shown in FIG. 9. In this case, as shown in FIGS. 6A and 6B, the substrate 1 'is preheated to a temperature equal to or higher than the solder melting point by the heater rail 5 and is intermittently conveyed. In a state where the substrate 1 ′ is intermittently conveyed and stopped, the solder supply device 4 of the solder application unit U1 feeds out the solder wire 2 and horizontally moves with a constant stroke in the left direction in FIG. 1 to be coated on the substrate 1 ′. Apply a certain amount of solder to the surface.

  The upper surface of the substrate 1 ′ is a rectangular coated surface that is elongated to the left and right. In FIG. 1, the first location P 1 is set at the center of the right end portion and the second location P 2 is set at the center of the left end portion. Is done. The solder application unit U1 applies the solder wire 2 continuously from the first location P1 to the second location P2 of the substrate 1 '.

  The solder supply device 4 of the solder application unit U1 includes a pair of feed rollers 9 and 10 that sandwich the solder wire 2, a roller drive control device 11 that rotates the feed rollers 9 and 10 forward and backward, and a vertical feed of the solder wire 2. A supply nozzle (not shown in FIG. 1) is provided. The solder supply device 4 is supported by an XY table (not shown) and freely moves in the horizontal XY direction. A drive control system 20 is incorporated in the solder application unit U1 having the solder supply device 4 as computer software for controlling the drive of the XY table. The drive control system 20 horizontally moves the entire solder supply device 4 in the left direction in FIG. The solder supply device 4 repeats the operation of feeding the solder wires 2 at a constant speed by moving the feed rollers 9 and 10 forward at a constant speed and pulling them up at a constant stroke by rotating them backward.

  FIG. 1A shows a state where the first location P1 of the substrate 1 ′ intermittently conveyed is stopped just below the solder wire 2 supported by the solder supply device 4. In this state, the feed rollers 9 and 10 rotate forward to feed the solder wire 2 straight down at a constant speed, and the tip (lower end) of the solder wire 2 is brought into contact with the first place P1 to preheat the substrate 1 ′. Melt. The state at this time is shown in FIG. 1B, and the tip of the solder wire 2 is melted at the first place P1 to form a circular molten solder 2'd. The drive control system 20 moves the entire solder supply device 4 in a direction parallel to the coated surface of the substrate 1 ′ (left in FIG. Direction) with a constant stroke. When the solder wire 2 is relatively moved from the first location P1 to the second location P2 of the substrate 1 ′ by this horizontal movement, as shown in FIGS. 1 (C) and 2 (B), the solder is continuously fed out. The wire 2 is melted on the substrate 1 ′ in order from the tip, and the molten solder 2d is applied in a horizontally long substantially elliptical shape on the surface to be coated of the substrate 1 ′. When the solder wire 2 moves to the second location P2, the feed rollers 9 and 10 are switched from the normal rotation operation to the reverse rotation operation, and the solder wire 2 is pulled up and separated from the molten solder 2d as shown in FIG. . This completes the one-stroke solder application operation on the substrate 1 '. When the solder application operation is completed, the drive control system 20 moves the solder supply device 4 back to the original position in FIG. 1A and waits for the next solder application to the substrate.

  FIG. 2A shows an enlarged view of the substantially circular molten solder 2'd shown in FIG. 1B, and FIG. 3A shows a plan view thereof. An enlarged view of the substantially elliptical molten solder 2d in FIG. 1C is shown in FIG. 2B, and a plan view is shown in FIG. 3B. 4A and 4B illustrate solder agitation shaping by the die bonder of FIG. 6, and FIG. 5 illustrates a solder application method when the solder application speed is variably controlled. The solder bonding method shown in FIGS. 1A to 1D is applied to the die bonder shown in FIG. 9 in the die bonder shown in FIGS. Before the detailed description of FIGS. 2 to 6, the structure and operation of the die bonder of FIG. 6 will be described.

  The die bonder of FIG. 6 intermittently conveys the lead frame 1 with the heater rail 5 while preheating to a temperature about the solder melting point. The solder application unit U1 shown in FIG. 6 includes a supply nozzle 12 that guides the tip of the solder wire 2. When the lead frame 1 is intermittently conveyed once and one substrate 1 ′ is carried directly under the solder application opening 8a, the solder application unit U1 moves the solder wire 2 directly from the state shown in FIG. To the first location P1 of the substrate 1 'and melted. The solder application unit U1 moves horizontally in the direction of the second portion P2 of the substrate 1 ′ by the drive control system 20 while feeding out the solder wire 2, and the solder wire 2 is placed on the substrate 1 ′ as shown in FIG. 6B. Is melted continuously from the tip to form a substantially elliptical molten solder 2d. When the continuous solder application is completed, the feed rollers 9 and 10 reversely rotate to pull up the solder wire 2, and the drive control system 20 returns the solder application unit U1 to the original position in FIG.

  When the coated substrate 1 ′ is transported immediately below the solder agitation shaping opening 8 b and stopped in the next intermittent conveyance of the lead frame 1, the agitation tool provided in the solder shaping unit U 2 as shown in FIG. 13 performs a work (tapping work) for pressing the molten solder 2d applied on the substrate 1 'to spread it flat. In this operation, the applied molten solder 2d is shaped into a molten solder 2e having the same size as that of the semiconductor chip 3. When the substrate 1 'is conveyed immediately below the chip supply opening 8c and stopped by the next intermittent conveyance of the lead frame 1, the chip supply tool 14 provided in the chip supply unit U3 is melted solder 2e in which the semiconductor chip 3 is shaped. Mount on top. The above-described solder application, solder shaping, and chip mounting are simultaneously performed at the respective work positions of the continuous openings 8a, 8b, and 8c as shown in FIG. 6B.

  As shown in FIGS. 2A and 3A, when the tip of the solder wire 2 is brought into contact with the first portion P1 of the substrate 1 ′ and melted, the circular molten solder 2′d is melted. There is almost no void generation due to segregation immediately after. As shown in FIGS. 2B and 3B, the solder wire 2 is moved horizontally to apply a substantially elliptical molten solder 2d on the substrate 1 '. The molten solder 2d is formed in a very short time from the first circular molten solder 2′d, and is obtained by melting the solder wire 2 sequentially on the substrate 1 ′ in order from the tip. There is almost no void generation due to segregation in 2d. Even if voids are generated, the peripheral portion of the substantially elliptical molten solder 2d is almost all, and there is almost no void generation in the central portion. FIG. 4A shows a molten solder 2e formed by pressing a substantially elliptical molten solder 2d with a stirring tool 13. FIG. The molten solder 2 e forms a substantially rectangular shape that is slightly larger than the semiconductor chip 3. As shown in FIG. 4B, even if voids are generated in the peripheral portion of the substantially elliptical molten solder 2d before shaping, the peripheral portion of the molten solder 2e shaped by expanding the molten solder 2d is dotted as shown in FIG. The void 30 moves to the position. Such voids 30 in the peripheral portion are located at the peripheral portion of the semiconductor chip 3 mounted on the molten solder 2e or at a portion outside the peripheral portion, and have little influence on the mountability and bonding quality of the semiconductor chip. Absent.

  Also, the substantially elliptical molten solder 2d shown in FIG. 3B has a stable shape that occupies most of the predetermined coated surface on the substrate 1 '. In other words, the separation distance between the first location P1 and the second location P2 is determined on the substrate 1 ′ so that the substantially elliptical molten solder 2d occupies most of the predetermined coated surface on the substrate 1 ′, and the solder wire Determine the feeding speed of 2. The molten solder 2d occupying most of the coated surface of the substrate 1 'is pushed out by the stirring tool 13 and shaped as shown in FIG. Since the shape of the molten solder 2d before shaping is stable and the area where the molten solder 2d is pushed and spread on the surface to be coated is small, the shape of the shaped molten solder 2e shown in FIG. The thickness is averaged. Therefore, the semiconductor chip 3 is mounted satisfactorily.

  In one solder application process in which the substantially elliptical molten solder 2d is applied to one substrate 1 ', the solder supply device 4 only moves the solder wire 2 up and down once, so that the solder application index becomes faster. . As the index becomes faster, segregation and voids generated in the molten solder 2d are reduced, and chip mountability is improved.

  In the solder application method described with reference to FIG. 6, the solder wire 2 is fed out to the substrate 1 ′ to be stopped at a constant speed, and the solder wire 2 is horizontally moved at a constant speed to apply the substantially elliptical molten solder 2 d to the substrate 1 ′. To do. Depending on the material of the substrate 1 ′ and the separation distance between the first location P 1 and the second location P 2, the overall amount and shape of the molten solder 2 d may not be stable, and the solder application amount may be insufficient at the intermediate portion of the molten solder 2 d. There is. In such a case, the horizontal movement speed of the solder wire 2 (relative movement speed with respect to the substrate 1 ') can be variably controlled. An example is shown in FIG.

  FIG. 5 shows a substantially elliptical molten solder 2d on the substrate 1 'and a movement speed graph of the solder wire 2 when this is applied. When the solder wire 2 is moved from the first place P1 toward the second place P2, the moving speed Vb in the intermediate time zone is controlled to be smaller than the moving speed Va at the beginning and end. In this way, the width Wb at the intermediate portion of the molten solder 2d becomes larger than the width Wa at both end portions, and the shortage of the solder application amount at the intermediate portion is eliminated.

  Further, in the solder application method of FIG. 6, the solder wire 2 is moved horizontally with respect to the substrate 1 'to be stopped to apply the substantially elliptical molten solder 2d to the substrate 1'. In the present invention, it is also possible to perform continuous solder application by horizontally moving the substrate 1 ′ with respect to the solder wire 2 moved up and down at a fixed position. An example of this will be described with reference to the operations of the two types of die bonders shown in FIGS.

  7A to 7C, the die bonder shown in the operation diagram of FIG. 7A continuously applies solder to the substrate 1 ′ with the solder wire 2 during the conveying operation of intermittently conveying the lead frame 1 along the heater rail 5. Do. FIG. 7A shows an initial transfer state when the chip mount is completed and the lead frame 1 is intermittently transferred. When the lead frame 1 is transported, the solder wire 2 is fed out at a constant speed, and the tip is brought into contact with the first location P1 of the substrate 1 'to be melted. When the wire feed is continued, the tip of the solder wire 2 is moved horizontally relative to the left side in FIG. 7 with respect to the substrate 1 ′ by the conveyed lead frame 1, and solder is continuously applied onto the substrate 1 ′. Is done. As shown in FIG. 7B, when the tip of the solder wire 2 moves relative to the second location P2 of the substrate 1 ′, the solder wire 2 is pulled up and separated from the continuously melted substantially elliptical molten solder 2d. . The lead frame 1 is transported by the remaining stroke and stopped. At this stop, as shown in FIG. 7C, the molten solder 2d applied in the course of carrying the lead frame moves to just below the solder stirring shaping opening 8b. In the state of FIG. 7C, the molten solder 2d is shaped by the stirring tool 13, and at the same time, the semiconductor chip 3 is mounted by the chip supply tool 14 on another shaped molten solder 2e. The melted solder 2d to be shaped shown in FIG. 7C is immediately after application, and there is almost no segregation or void generation, and the melted solder 2d just after application has good shapeability and can be shaped in a stable shape.

  The die bonder shown in the operation diagrams of FIGS. 8A to 8C is obtained by omitting the stirring tool 13 from the die bonder of FIG. When solder application is performed using intermittent conveyance of the lead frame 1, the substantially elliptical molten solder 2d immediately after application spreads over the surface to be coated of the substrate 1 'with an average thickness, and is shaped. It is possible to directly mount the chip without using it. An example of the operation is shown in FIGS.

  FIG. 8A shows a state where the solder wire 2 is drawn out and melted at the first location P1 of the substrate 1 'from the tip. At this time, the chip supply tool 14 mounts the semiconductor chip 3 on the molten solder 2d on another substrate 1 '. FIG. 8B shows a state in which the solder wire 2 is relatively moved while the lead frame 1 is conveyed to apply the substantially elliptical molten solder 2d on the substrate 1 '. FIG. 8C shows a state in which the continuous solder application is finished and the lead frame 1 is intermittently conveyed and stopped. When the lead frame 1 is stopped, the next solder application and chip mounting are performed simultaneously. As described above, by performing chip mounting immediately after solder application, the solder shaping process and position are omitted, and the index of the die bonder can be improved.

(A)-(D) are the perspective views at the time of each operation | movement of the principal part of the board | substrate and solder wire for demonstrating the solder application | coating method of this invention. 1A is a partially enlarged side view of FIG. 1B, and FIG. 1B is a partially enlarged side view of FIG. 2A is a plan view of FIG. 2A, and FIG. 2B is a plan view of FIG. (A) is a plan view when the molten solder is shaped, and (B) is an X-ray projection view thereof. It is a top view of the molten solder for explaining another solder application method of the present invention, and a graph of relative movement speed. (A), (B) is the fragmentary sectional view at the time of each operation | movement which shows embodiment of a die bonder. (A)-(C) are the fragmentary sectional views at the time of each operation | movement which shows embodiment of another die bonder. (A)-(C) are the fragmentary sectional views at the time of each operation | movement which shows embodiment of another die bonder. It is a fragmentary sectional view of the conventional die bonder. 9 is a perspective view of the main part of the solder application unit in the die bonder. 10 is a plan view of the substrate coated with solder in the solder application unit. FIG. 12 is a plan view of the molten solder of FIG. 11 shaped. FIG. 12 is an X-ray projection view of the shaped solder of FIG. 11.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lead frame 1 'Board | substrate, island 2 Solder wire 2d Molten solder 2e Molten solder 3 Semiconductor chip 4 Solder supply apparatus 5 Heater rail 7 Lead frame conveyance path 9, 10 Feed roller 11 Roller drive control apparatus 12 Supply nozzle 13 Stirring tool 14 Chip Supply tool 20 Drive control system 30 Void P1 First location P2 Second location U1 Solder application unit U2 Solder shaping unit U3 Chip supply unit

Claims (7)

A solder coating method for applying a fixed amount of solder to the coated surface by bringing the tip of the solder wire fed from the solder supply device into contact with the coated surface of the substrate preheated to a temperature higher than the melting point of the solder. ,
The solder wire is fed from the solder supply device to the first place and the first place that are separated from each other on the surface to be coated and melted from the tip to the second place on the surface to be coated. A solder application method, wherein the solder is applied continuously from a first location to a second location on a surface to be coated by relative movement in a direction parallel to the surface to be coated.   The solder wire is fed out from the solder supply device at a constant speed, and the relative movement speed of the solder wire from the first place to the second place with respect to the coated surface is variably controlled so as to be non-constant. The solder application method according to claim 1.   The lead frame in which the substrate is intermittently conveyed in a substantially horizontal direction, and the solder wire is moved relative to the lead frame when the lead frame is stopped after intermittent conveyance. Solder application method.   A lead frame in which the substrate is intermittently conveyed in a substantially horizontal direction, and the solder wire fed out from the solder supply device at a fixed position toward the lead frame is moved relative to the lead frame when the lead frame is conveyed. The solder application method according to claim 1, wherein: A predetermined amount of solder is applied to the coated surface by bringing the tip of the solder wire fed from the solder supply device into contact with the coated surface of the lead frame that is preheated to the melting point of the solder and is intermittently conveyed in a substantially horizontal direction. A solder application unit for applying
The solder wire is fed from the solder supply device to the first and second locations separated on the coated surface of the lead frame and melted from the tip, and the solder wire is applied to the coated surface. Relatively move both the solder supply device and the lead frame so that the solder is continuously applied from the first location to the second location on the coated surface by relatively moving in the direction parallel to the coated surface to the second location. A solder application unit comprising a drive control system for movement. A predetermined amount of the lead frame that is preheated to the melting point of the solder and is intermittently conveyed in a substantially horizontal direction is brought into contact with the predetermined coated surface of the lead frame to be melted by contacting the tip of the solder wire fed from the solder supply device. A die bonder comprising a solder application unit for applying a solder and a chip supply unit for mounting a semiconductor chip on the molten solder applied to the surface to be applied by the solder application unit,
The solder application unit is configured to draw out the solder wire from the solder supply device to the first place of the first place and the second place provided on the coated surface of the lead frame and melt the solder wire from the tip. The solder supply device so as to apply the solder continuously from the first location to the second location on the coated surface by relatively moving the wire to the second location on the coated surface in a direction parallel to the coated surface; A die bonder comprising a drive control system for relatively moving both lead frames.   A solder shaping unit is provided that presses the molten solder on the coated surface applied by the solder application unit with a flat pressing surface of a stirring tool to stir and shape the semiconductor chip before mounting the semiconductor chip by the chip supply unit. The die bonder according to claim 6.

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