JP2009190067A - Laser welding method, semiconductor device, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser welding method by which, even if an upper side member has a small heat capacity and the vicinity of a weld portion is a body of small heat capacity, high joining strength is obtained, and a semiconductor device, and its manufacturing method. <P>SOLUTION: When superimposing an upper side member 5, which has a small heat capacity, on a lower side member 1 and laser welding them, a heat transfer probe 8 for heatsinking a heat generated in welding is pressed against the vicinity of a laser weld portion 6. Thereby, melt rising of a weld part 9 is prevented and a joining area is secured, so that high joining strength is obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laser welding method and a semiconductor device manufacturing method capable of ensuring high joint strength even when laser welding is performed in a state where two members are overlapped, even when the thermal conductivity and heat capacity of an upper member are small.

FIGS. 6A and 6B are configuration diagrams when the upper member having a large heat capacity is welded. FIG. 6A is a plan view of the main part, and FIG. 6B is a weld cut along line XX in FIG. It is subsequent principal part sectional drawing. The upper member 2 is a member having a large area, a large thickness, and a large heat capacity, and the portion irradiated with laser irradiation (laser irradiation portion 6) is separated from the end of the upper member 2. Further, the welding members are the upper member 2 and the lower member 1.
The laser beam 4 is irradiated on the surface of the upper member 2 in a state where the two members are overlapped, and the upper member 2 and the lower member 2 are welded. The upper member 2 having a large heat capacity is formed with a good welded portion 27 between the lower member 1 and a required welding area can be obtained by adjusting the power density of the laser light 4 to be irradiated.
This power density is determined by the power of the laser beam 4 and the area to be irradiated. In order to increase the power density, the laser power may be increased or the irradiation area may be decreased. When it is desired to reduce the power density, the laser power may be decreased or the irradiation area may be increased.
On the other hand, when the heat capacity of the upper member 2 is small, the upper member 2 is melted before the temperature is raised to a temperature at which the lower member 1 is sufficiently melted, and the laser power is consumed for the melting. A sufficient weld area with 1 cannot be obtained. In particular, when the upper member has a low thermal conductivity, the melt-up becomes significant. This will be described next.

FIGS. 7A and 7B are configuration diagrams in the case of welding the upper member having a small heat capacity. FIG. 7A is a plan view, and FIG. 7B is a state immediately after laser irradiation cut along the XX line of FIG. The principal part sectional drawing of this, and the figure (c) are principal part sectional drawings after the welding cut | disconnected by the XX line of the figure (a). FIG. 7 shows a case where the upper member 5 has a small thermal conductivity and has an elongated rectangular shape, and the laser welding location 6 is near the end of the upper member 5.
The upper member 5 is superimposed on the upper surface of the lower member 1 as shown in FIG. 5A, and the laser beam 4 is irradiated on the surface near the end of the upper member 5 as shown in FIG. As shown in FIG. 3C, the tip portion of the upper member 5 is melted.
When the upper member 5 having a narrow and narrow width and a low thermal conductivity as shown in FIG. 7 is welded, the irradiated laser beam 4 is absorbed in the vicinity of the laser irradiation point 6 of the upper member 5 and converted into thermal energy. Heated.
When the thermal conductivity of the upper member 5 is small and the shortest distance L from the laser irradiation point 6 to the end of the upper member 5 is small, the upper side near the laser irradiation point 6 is reached before the lower member 1 reaches the melting point temperature. When the member 5 rapidly reaches the melting point temperature and the lower member 1 is not sufficiently melted, the tip portion of the upper member 5 is melted and melted in the welded portion 28 as shown in FIG. A rise 7 is produced.

In such a welded portion 28, even if the upper member 5 melts up, it does not melt into the lower member 1, and the welded portion 28 is only in contact with the surface of the lower member 1. In this case, the joint strength of the welded portion 28 is significantly reduced.
In order to avoid this melt-up 7, it is conceivable to lower the power density by reducing the power of the laser beam 4 or increasing the irradiation area. However, when the power density is lowered, the temperature of the lower member 1 is reduced. It is difficult to obtain the welded portion 27 as shown in FIG.
By the way, in laser welding, there are a welding form by keyhole formation accompanying the evaporation of the welding member and a welding form simply by heat conduction. In order to form the welded portion 27 having a vertically long shape (the melt depth is larger than the nugget diameter (surface melt diameter)) as shown in FIG. There is a need.
A feature of this keyhole type welding is that welding can be performed by short-time pulse laser irradiation. A member having a small surface area such as the elongated upper member 5 as shown in FIG. This is advantageous.
However, even in the case of this keyhole type welding, in a member having a small thermal conductivity and a small heat capacity, heat is accumulated and the member melts up 7 to reduce the joining area and the joining strength.

In particular, when the width of the upper member 5 is narrow, the melt 7 becomes noticeable in the case of a small heat capacity body having a small volume V within the shortest distance L from the end of the member 5 to the laser irradiation point 6.
For example, when the width W of the upper member is 1.5 mm and the thickness T is 0.8 mm, when the shortest distance L from the end of the upper member 5 to the laser beam irradiation point 6 is 3 mm, the volume V is L × W × T = 3 mm × 1.5 mm × 0.8 mm = 3.6 mm ³ When the volume V is reduced to such a degree, in a member having a low thermal conductivity, even if it is a keyhole type, heat is accumulated and melted 7 occurs. Since it has been experimentally confirmed that the melt 7 is less likely to occur when the volume V is about 4 mm ³ or more. Here, for convenience when the volume V is 4 mm ³ or less, this portion is referred to as a small heat capacity body. I will call it.
As the keyhole type laser beam 4, a YAG laser (wavelength 1064 nm) or a second harmonic of a YAG laser (wavelength 532 nm) can be used.
On the other hand, in the heat conduction type welding mode, a vertically long melted portion cannot be obtained. Therefore, in order to obtain a desired welding area, it is necessary to irradiate the laser for a longer time than in the case of the YAG laser.
A semiconductor laser (wavelength: 600 nm to 900 nm) can be used as the laser beam for heat conduction welding. In the case of heat conduction type welding, the laser beam is irradiated for a long time. Therefore, in the case of a member having a small thermal conductivity as shown in FIG. The welded heat is accumulated in the upper member 5, and the upper member 5 melts before being welded to the lower member 1, and a desired welding area cannot be obtained.

In a YAG laser that can be welded in a short time, when the thermal conductivity is a member with a small heat capacity in the vicinity of the laser welding location, excessive melting 7 of the member occurs as described above. In particular, when stainless steel or phosphor bronze having a small thermal conductivity is used as the upper member 5, it appears remarkably when the volume of the upper member 5 at the location to be welded is small and the heat capacity is small. This phosphor bronze has a spring action and is often used as a material for control terminals in semiconductor devices.
8 to 10 are manufacturing process diagrams showing a conventional method of manufacturing a semiconductor device in the order of processes. In each process diagram, (a) is a plan view of a main part manufacturing process, and (b) is an X- It is principal part manufacturing process sectional drawing cut | disconnected by X-ray | X_line.
8 to 10 show steps in the case of laser welding the control terminal 17 to the control terminal pad 12 formed on the insulated circuit board 40. FIG.
8A and 8B, the IGBT chip 13 is joined to the insulating circuit board 40 including the ceramics 10, the collector copper foil 11, and the control terminal pads 12 with solder 15. As a process, the solder 15 is disposed on the upper surface of the collector copper foil 11 formed on the insulating circuit board 40, the IGBT chip 13 is placed thereon, and the solder 15 is melted by heating, and then cooled. The copper foil 11 and the IGBT chip 13 are joined.

Next, in FIG. 9A and FIG. 9B, the control signal pad 14 for extracting an electric signal formed on the IGBT chip 13 and the control terminal pad 12 formed on the insulating circuit board 40 are used. Electrical connection is made with an aluminum wire 16.
Next, in FIGS. 10A and 10B, the phosphor bronze control terminal 17 is pressed against the control terminal pad 12, and the welded portion 22 is attached at a position where the laser beam 19 is irradiated (laser irradiation position 18). Form. The material of the control terminal 17 used here is phosphor bronze, and the surface is plated with tin for the subsequent soldering process. The thermal conductivity of phosphor bronze is 67 W / mK, which is about 17% of pure copper.
FIG. 11 is an enlarged view of a part A in FIG. 10. FIG. 11 (a) is a diagram showing a state in which the control terminal 17 has not yet begun immediately after laser irradiation, and FIG. It is the figure of the state which melted and re-solidified by.
In FIG. 11, for example, when the width W of the control terminal is 1.5 mm and the thickness T is 0.8 mm, if the laser beam is irradiated to the position of the shortest distance L from the end of the control terminal, the small capacity The volume V of the body is 3 mm × 1.5 mm × 0.8 mm = 3.6 mm ³ . When the volume V of the small-capacity body is reduced to this extent, heat is accumulated in a member having a low thermal conductivity such as phosphor bronze even if it is a keyhole type, and melts 20 in the welded portion 29.

The laser beam used is a YAG laser (wavelength 1064 nm) and the spot diameter is φ0.4 mm to φ1.0 mm. When pure copper is used as the material of the control terminal 17, even when the above-described control terminal 17 has a small heat capacity, heat at the time of welding can easily escape to the lower control terminal pad 12, so as shown in FIG. There is no excessive melt 20.
However, since there is no spring action compared to phosphor bronze, it is difficult to keep the state pressed against the control terminal pad 12. For this reason, in order to use pure copper for the material of the control terminal 17, a jig for holding the control terminal 17 under pressure during welding is required. When phosphor bronze is used, a jig is unnecessary because the terminal case in which phosphor bronze (not shown) is insert-molded can keep the control terminal 17 pressed against the control terminal pad 12.
However, when phosphor bronze is used as the material of the control terminal 17, heat is accumulated when the thermal conductivity is about 1/5 of pure copper and the volume V is 4 mm ³ or less. Therefore, there is a disadvantage that the melt 20 is excessively generated.
As described above, when the melted-up 20 occurs, the welded portion 29 of the control terminal 17 that has been melted and re-solidified does not melt into the control terminal pad 12 and the joint strength is extremely reduced.
Moreover, in patent document 1, when welding a high-strength steel plate with a laser welding method, it is disclosed that welding is performed while cooling a roll-type heat removal body in the vicinity of the rear of the laser irradiation position with respect to the welding progress direction. Has been.
JP 2006-68808 A

In this way, when the upper member 5 (control terminal 17) having a small thermal conductivity is a small heat capacity body in the vicinity of the welded portion, the welded portion 28 (welded portion 29) melts excessively, so that a sufficient welding area is obtained. It becomes difficult to ensure.
Further, in Patent Document 1, both the upper member and the lower member are for large-area steel plates, and a roll type is described as the heat removal body, but the upper member such as a control terminal of a semiconductor device is used. In the case where the vicinity of the welded portion is a small heat capacity body, there is no description about a method for suppressing heat absorption by the heat removal body and preventing excessive melting of the upper member by laser welding.
The object of the present invention is to solve the above-mentioned problems and ensure a sufficient welding area without excessive melting even when the vicinity of the welded portion is a small heat capacity body with an upper member having a low thermal conductivity, and a high joint strength. A laser welding method and a semiconductor device and a method of manufacturing the same.

In order to achieve the above object, in the laser welding method for joining two members by irradiating the upper member with laser light in a state where the two members are overlapped, in the vicinity of the portion of the upper member where the laser is irradiated A method of performing laser welding by contacting a heat-extracting body to the surface.
In addition, the shape of the upper member is a long and narrow rectangle, and the portion irradiated with the laser is located in the vicinity of one end in the longitudinal direction of the upper member, and one end in the longitudinal direction from the portion irradiated with the laser It is effective for the upper member which is a small heat capacity body in which the volume of the upper member calculated by the product of the shortest distance to the part, the width of the upper member and the thickness of the upper member is a predetermined volume or less.
Further, it is effective in the case of the upper member in which the material of the upper member is less than half the thermal conductivity of pure copper and the predetermined volume is 4 mm ³ .
The heat removal body is a heat transfer probe that transfers heat to the outside, and laser welding is performed while pressing the heat transfer probe against the upper member.
Moreover, the thermal conductivity of the material of the heat transfer probe is preferably equal to or higher than that of the upper member to be welded.
Further, when the other end portion of the heat transfer probe that is not in contact with the upper member is connected to a cooling means (cooling body or the like), the heat removal effect can be enhanced when laser welding is continuously performed.

Further, it is effective that the wavelength of the laser beam used for the laser welding is 1064 nm (YAG laser) or 532 nm (second harmonic of YAG laser).
In addition, a plurality of circuit patterns constituting the insulated circuit board, a semiconductor chip fixed to the first circuit pattern of the circuit patterns with solder, and a control signal fixed to the second circuit pattern by laser welding are transmitted. In the semiconductor device including the control terminal, the control terminal and the second circuit pattern may be fixed to each other at a weld formed while the heat generated by the laser welding is removed by a heat transfer probe.
The thermal conductivity of the control terminal may be less than or equal to half that of pure copper.
Further, the effect is exhibited when the material of the control terminal is phosphor bronze having a spring action.
In addition, a plurality of circuit patterns constituting the insulated circuit board, a semiconductor chip fixed to the first circuit pattern of the circuit patterns with solder, and a control signal fixed to the second circuit pattern by laser welding are transmitted. In the method of manufacturing a semiconductor device including the control terminal, the laser welding may be performed while the heat generated by the laser welding is removed by a heat transfer probe pressed against the control terminal.

  Embodiments will be described in the following examples. In addition, the same code | symbol was attached | subjected to the site | part same as the site | part of a conventional structure.

1A and 1B are configuration diagrams showing a laser welding method for a small heat capacity body according to a first embodiment of the present invention, in which FIG. 1A is a plan view of an essential part and FIG. 1B is an X of FIG. 1A. FIG. 6C is a cross-sectional view of the main part immediately after laser irradiation cut by -X-ray, and FIG.
The upper member 5 is overlapped on the upper surface of the lower member 1, and the laser beam 4 is irradiated in a state where the heat transfer probe 8 is pressed against a portion of the upper member 5 close to the laser irradiation spot 6 (place where laser irradiation is performed). The upper member 5 has an elongated rectangular shape and its width is narrow. The laser beam 4 is absorbed by the surface of the upper member 5 and converted into thermal energy, so that the laser irradiation portion 6 of the upper member 5 is melted. Here, since the upper member 5 irradiated with the laser beam has only a few times the width of the irradiated laser spot diameter, heat is accumulated. In particular, the material of the upper member 5 is less than half of the thermal conductivity of pure copper, the shape of the upper member 5 is an elongated rectangle, the laser irradiation spot 6 is located near the end of the upper member 6, and the laser irradiation spot When the volume 25 of the upper member calculated by the product of the shortest distance L, the width W of the upper member 5 and the thickness T of the upper member 6 is as small as 4 mm ³ or less, the location is It becomes a small heat capacity body and heat accumulation becomes remarkable.
However, since the heat transfer probe 8 is pressed in the vicinity of the laser irradiation spot 6, the heat is conducted to the heat transfer probe 8 and is removed, so that the heat input to the welded portion 9 of the upper member 5 is excessive. There is nothing. For this reason, there is no melting as shown in FIG. 7C, and a sufficient welding area can be secured.

When the volume V is larger than 4 mm ³ , the heat capacity is increased, so that the melting is reduced and it is not always necessary to press the heat transfer probe 8.
Further, in FIG. 1C, the end of the upper member 5 is not melted. However, when the volume V is further reduced, it melts to the end, but since heat is removed by the heat transfer probe 8, welding is performed. The portion 9 does not rise and a high bonding strength is obtained.
As shown in FIG. 2, a cooling body 30 may be attached to the other end of the heat transfer probe 8 that does not contact the upper member 5 so that the heat transfer probe 8 is not stored with heat. In particular, in the case of continuous laser welding, the heat transfer probe 8 gradually accumulates heat, so it is effective to attach the cooling body 30 that releases heat. Further, the cooling body 30 is not limited as long as it is a cooling means that can effectively remove heat from the heat transfer probe 8.
Further, the thermal conductivity of the heat transfer probe 8 is preferably equal to or higher than the thermal conductivity of the upper member 5. Of course, a larger value is desirable because the heat removal effect of the heat transfer probe 8 is increased.
It is also effective to manufacture the heat transfer probe 8 with a heat pipe that efficiently releases heat to the outside.
Further, it is preferable that the tip of the heat transfer probe 8 is wider than the width of the upper member 5 having a small heat capacity to be in contact with the heat transfer probe 8 because heat conduction can be performed efficiently.
Further, the wavelength of the laser beam 4 used is preferably 1064 nm (YAG laser) or 532 nm (second harmonic of the YAG laser).

FIG. 3 is a block diagram of a semiconductor device according to a second embodiment of the present invention. FIG. 3 (a) is a plan view of an essential part, and FIG. 3 (b) is cut along line XX in FIG. 3 (a). It is principal part sectional drawing. This semiconductor device is a block diagram of a semiconductor device manufactured using the laser welding method of FIG.
In the configuration of this semiconductor device, an IGBT chip 13 as a semiconductor chip is fixed to a collector copper foil 11 which is a circuit pattern of the insulating circuit board 40 via a solder 15, and the control signal pad 14 of the IGBT chip 13 and the insulating circuit board 40 are fixed. These control terminal pads 12 are connected by an aluminum wire 16. The control terminal pad 12 made of pure copper and the control terminal 17 made of phosphor bronze are fixed by a welded portion 22 by laser welding while pressing the heat transfer probe 21. The control terminal 17 is a terminal that transmits a control signal.
The control terminal 17 and the control terminal pad 21 of the insulated circuit board 40 are well welded without being melted by laser welding while pressing the heat transfer probe 21 against the phosphor bronze control terminal 17. In some cases, the pressed trace (the trace 31 in FIG. 3) remains on the control terminal 17 pressed against the heat transfer probe 21.
Further, since the phosphor bronze control terminal 17 has a spring action, even when the external pressure contact force is small, the adhesion between the control terminal 17 and the control terminal pad 12 is improved, and laser welding can be performed.

The phosphor bronze of the control terminal 17 has a thermal conductivity as small as about 1/5 of pure copper. 1, the volume of the control terminal represented by the product of the shortest distance L from the laser irradiation point 18 to the end of the control terminal 17, the width W of the control terminal 17, and the thickness T of the control terminal 17. V (volume V in FIG. 4 described later) is 3 mm × 1.5 mm × 0.8 mm = 3.6 mm ³ . This volume V is 4 mm ³ or less, and since it is a small heat capacity body, the temperature easily rises and melts up due to the laser power, but it is prevented by laser welding while removing heat with the heat transfer probe 21. it can.

4A and 4B are views showing a method of manufacturing a semiconductor device according to a third embodiment of the present invention. FIG. 4A and FIG. 4B are cross-sectional views of manufacturing steps shown in the order of steps. a) is a sectional view of the manufacturing process immediately after laser irradiation, and (b) is a sectional view of the manufacturing process after welding. This manufacturing process cross-sectional view corresponds to the cross section of the portion A in FIG.
FIG. 4 shows a manufacturing method of the semiconductor device of FIG. 3, and the heat transfer probe 21 is attached during laser welding of the pure copper control terminal pad 12 and the phosphor bronze control terminal 17 of the insulating circuit board 40 used in the semiconductor device. Used.
The laser light 19 is irradiated in a state where the phosphor bronze control terminal 17 is pressed against the pure copper control terminal pad 12 formed on the insulating circuit board 40. At this time, since the heat transfer probe 21 is pressed in the vicinity of the laser irradiation spot 18, the heat generated by the laser light is conducted to the heat transfer probe 21 without being accumulated in the control terminal 17 having a small heat capacity, and welded. The portion 22 does not melt excessively, and a sufficient welding area can be secured.
As a material for the heat transfer probe 21, a material equivalent to or higher than the thermal conductivity of the control terminal 17 (phosphor bronze) to be welded is preferably used. For example, pure copper or copper alloy is preferable.
Although the shape of the heat transfer probe 21 in FIG. 4 is a cylindrical column with a taper, the shape is not limited to this, and may be a prismatic shape as long as it can conduct heat. Moreover, it is good also as a shape with a level | step difference like the heat-transfer probe 23 shown in FIG.

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows the laser welding method of the small heat capacity body of 1st Example of this invention, (a) is a principal part top view, (b) is immediately after laser irradiation cut | disconnected by the XX line of (a). Cross-sectional view of the main part, (c) is a cross-sectional view of the main part after welding cut along line XX in (a) The figure which attached the cooling body 30 to the other end of the heat-transfer probe 8 which does not contact the upper member 5 It is a block diagram of the semiconductor device of 2nd Example of this invention, (a) is a principal part top view, (b) is principal part sectional drawing cut | disconnected by the XX line of (a). FIG. 4 is a manufacturing method of a semiconductor device according to a third embodiment of the present invention, wherein (a) and (b) are manufacturing process cross-sectional views shown in the order of processes; (a) is a manufacturing process cross-sectional view immediately after laser irradiation; ) Cross-sectional view of the manufacturing process after welding Illustration of heat transfer probe with steps It is a block diagram at the time of welding the upper member with a large heat capacity, (a) is a principal part top view, (b) is principal part sectional drawing after the welding cut | disconnected by the XX line of (a). It is a block diagram in the case of welding an upper member with a small heat capacity, (a) is a plan view, (b) is a main part cross-sectional view immediately after laser irradiation cut by the XX line of (a), (c) is Sectional drawing of the principal part after welding cut | disconnected by the XX line of (a) Manufacturing process diagram of conventional semiconductor device manufacturing method FIG. 8 is a manufacturing process diagram illustrating a conventional method for manufacturing a semiconductor device. FIG. 9 is a manufacturing process diagram illustrating a conventional method for manufacturing a semiconductor device. It is the A section enlarged view of Drawing 10, (a) is a figure in the state where control terminal 17 has not yet begun to melt immediately after laser irradiation, and (b) is the control terminal 17 melted by laser beam 19, and re-solidified. State diagram

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lower member 2, 5 Upper member 4, 19 Laser beam 6 Laser irradiation place 7 Melting up 8, 21, 23 Heat transfer probe 9, 22 Welding part 10 Ceramics 11 Collector copper foil 12 Pad for control terminal 13 IGBT chip 14 Control Signal pad 15 Solder 16 Aluminum wire 17 Control terminal 18 Laser irradiation point 30 Cooling body 31 Pressing trace 40 Insulated circuit board L Shortest distance W Width T Thickness V Volume (volume of small heat capacity body)

Claims (11)

In the laser welding method for joining two members by irradiating the upper member with laser light in a state where the two members are overlapped, a heat removal body is brought into contact with the laser irradiation portion of the upper member in the vicinity of the laser irradiation. Laser welding method characterized by performing. The shape of the upper member is a long and narrow rectangle, and the portion irradiated with the laser is located near one end in the longitudinal direction of the upper member, from the portion irradiated with the laser to one end in the longitudinal direction. 2. The laser according to claim 1, wherein the volume of the upper member calculated by a product of the shortest distance of the first member, the width of the upper member, and the thickness of the upper member is a small heat capacity body having a predetermined volume or less. Welding method. ^3. The laser welding method according to claim 2, wherein a material of the upper member is not more than half of a thermal conductivity of pure copper, and the predetermined volume is 4 mm ³ . The laser welding method according to claim 1, wherein the heat removal body is a heat transfer probe that transfers heat to the outside, and laser welding is performed while pressing the heat transfer probe against the upper member. The laser welding method according to claim 4, wherein the heat conductivity of the material of the heat transfer probe is equal to or higher than that of the upper member to be welded. 6. The laser welding method according to claim 4, wherein the other end portion of the heat transfer probe not in contact with the upper member is connected to a cooling means. The laser welding method according to claim 1, wherein a wavelength of laser light used for the laser welding is 1064 nm (YAG laser) or 532 nm (second harmonic of YAG laser). Control for transmitting a plurality of circuit patterns constituting the insulated circuit board, a semiconductor chip fixed to the first circuit pattern among the circuit patterns by solder, and a control signal fixed to the second circuit pattern by laser welding A semiconductor device comprising: a terminal, wherein the control terminal and the second circuit pattern are fixed to each other by a weld formed by removing heat generated by the laser welding with a heat transfer probe. . The semiconductor device according to claim 8, wherein the thermal conductivity of the control terminal is not more than half of the thermal conductivity of pure copper. The semiconductor device according to claim 9, wherein a material of the control terminal is phosphor bronze having a spring action. Control for transmitting a plurality of circuit patterns constituting the insulated circuit board, a semiconductor chip fixed to the first circuit pattern among the circuit patterns by solder, and a control signal fixed to the second circuit pattern by laser welding A method of manufacturing a semiconductor device comprising: a terminal, wherein heat generated by the laser welding is removed by a heat transfer probe pressed against the control terminal.

Images