Method for connecting inner leads, method for manufacturing a semiconductor device, method for manufacturing electrical equipment, and semiconductor device.

Abstract

This invention provides an inner lead connection method that enables laser bonding of the circuit pattern on a circuit board to the inner lead with stable and high bonding strength. [Solution] A method for connecting inner leads, comprising: laser welding an inner lead to a lead frame having an inner lead with a lower surface that contacts the metal pattern of a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface, by irradiating a laser beam from the upper surface of the inner lead, wherein the upper surface of the metal pattern and the lower surface of the end of the inner lead are brought into contact, and the end of the inner lead is pressed from above using a pressing jig equipped with a plurality of pressing claws for pressing the end of the inner lead against the upper surface of the metal pattern, and a laser beam is irradiated from one pressing claw towards the other in the region between the plurality of pressing claws, thereby laser welding the metal pattern of the circuit board and the inner lead.

Description

Technical Field

[0001] The present disclosure relates to a method of connecting inner leads, a method of manufacturing a semiconductor device, a method of manufacturing an electrical device, and a semiconductor device.

Background Art

[0002] Conventionally, a semiconductor module is known in which a semiconductor chip is mounted on an insulating circuit board on which a circuit pattern is formed, and the circuit pattern on the insulating circuit board to which the semiconductor chip is bonded is connected by a wiring portion such as a lead frame. In FIG. 6 of Patent Document 1 and the related description section, it is described that a lead frame is placed on a circuit pattern of an insulating circuit board, and a laser beam is irradiated from above to the bonding portion to weld and bond the lead frame.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] When joining is performed using the joining method described in Patent Document 1 above, as shown in Figure 12, the lead frame 15 is positioned so that the lower surface of the end 14A of the inner lead 14 of the lead frame 15 is in contact with the circuit pattern (metal pattern 11 on the ceramic substrate 12) of the circuit board 13 on which the semiconductor chip 10 is mounted. With the inner lead 14 and the circuit pattern stacked together, the joining is performed by irradiating laser light L through the inner lead 14. The laser irradiation range at this time is a very small area of ​​about 1 mm, although it depends on the size of the circuit pattern and the inner lead. If laser irradiation is performed when the contact between the circuit pattern and the inner lead is insufficient, there is a risk that the joining (welding) strength will be insufficient. Also, although there are usually multiple joining points between the circuit pattern and the inner lead, there was a problem that the joining strength between the joining points varied.

[0005] This disclosure was made to solve the above problems and aims to provide an inner lead connection method that enables laser welding of the inner lead to the circuit pattern of a circuit board with stable and high bonding strength.

[0006] This disclosure also aims to provide a semiconductor device in which the circuit pattern and inner leads of a circuit board are laser-welded with stable and high bonding strength, thereby improving reliability. [Means for solving the problem]

[0007] This disclosure is made to achieve the above objective and provides a method for connecting an inner lead, which involves laser welding an inner lead to a lead frame having an inner lead having a lower surface at its end that contacts the metal pattern on the surface of a circuit board on which a semiconductor chip is mounted, by irradiating the inner lead with laser light from the upper surface side, wherein the upper surface of the metal pattern and the lower surface of the end of the inner lead are brought into contact, and the end of the inner lead is pressed from above using a pressing jig equipped with a plurality of pressing claws for pressing the end of the inner lead against the upper surface of the metal pattern, and the laser light is irradiated in the region between the plurality of pressing claws from one pressing claw towards the other pressing claw, thereby laser welding the metal pattern on the circuit board and the inner lead.

[0008] This method of connecting inner leads allows for stable and high-strength laser bonding between the metal pattern on the circuit board and the inner leads.

[0009] In this case, the connection method for the inner lead can be such that the aforementioned irradiation while traveling is performed multiple times.

[0010] This allows for laser bonding of the circuit board's metal pattern and inner leads with greater stability and higher bonding strength by expanding the welding area while suppressing damage to the circuit board.

[0011] In this case, when the number of times is N times (where N≧2), the inner lead connection method can be used to superimpose the laser irradiation area of ​​the Nth time onto a portion of the laser irradiation area of ​​the N-1 time.

[0012] This allows for laser bonding of the metal patterns and inner leads of the circuit board with even greater stability and higher bonding strength by expanding the welding area while suppressing damage to the circuit board.

[0013] In this case, when the number of times is N times (where N≧2), the inner lead connection method can be used to separate the laser irradiation area of ​​the N-1th time the laser is irradiated while traveling and the laser irradiation area of ​​the Nth time the laser is irradiated while traveling in the direction of the laser being irradiated.

[0014] This allows for laser bonding of the metal patterns and inner leads of the circuit board with even greater stability and higher bonding strength by expanding the welding area while suppressing damage to the circuit board.

[0015] In this case, following the aforementioned traveling irradiation, the inner lead connection method can be further configured to irradiate the laser beam from the other pressing claw toward the one pressing claw.

[0016] This allows for laser bonding of the metal patterns and inner leads of the circuit board with even greater stability and higher bonding strength by expanding the welding area while suppressing damage to the circuit board.

[0017] In this case, the pressing jig equipped with two pressing claws can be used, and the starting position when the laser beam is irradiated from one of the pressing claws toward the other pressing claw is set to approximately the midpoint between the two pressing claws, and the starting position when the laser beam is irradiated from the other pressing claw toward the one pressing claw is set to approximately the same position as the starting position when the laser beam is irradiated from one of the pressing claws toward the other pressing claw in this inner lead connection method.

[0018] This allows for laser bonding of the metal pattern on the circuit board to the inner leads with high stability and bonding strength, while suppressing damage to the circuit board.

[0019] In this case, the connection method for the inner lead can be such that the laser beam is directed and irradiated using a galvanoscan method.

[0020] As a result, high-throughput and highly accurate laser welding can be achieved.

[0021] At this time, it is possible to adopt a method of connecting an inner lead in which laser light is traveled and irradiated from the pressing claw on the side closer to the distance from the laser irradiation center point in the galvanometer scanning type laser irradiation toward the other pressing claw on the side farther from the laser irradiation center point.

[0022] As a result, the area (range) of the laser bonding portion can be made larger.

[0023] At this time, a plurality of the circuit boards are arranged on a receiving jig, and the positions of the laser light irradiator and the receiving jig are adjusted so that the laser irradiation center point is located between the plurality of circuit boards, and for each of the plurality of circuit boards, It is possible to adopt a method of connecting an inner lead in which the metal pattern and the inner lead are laser welded.

[0024] As a result, high-throughput and highly accurate laser welding can be achieved.

[0025] At this time, for each of the plurality of circuit boards arranged on the receiving jig, a lead frame provided with inner leads in which a plurality of lead patterns are arranged in a grid-strip shape is prepared, the lead patterns of the lead frame are arranged facing each other, and the laser light irradiator and the receiving jig are adjusted so that the laser irradiation center point is located at the center between the lead patterns of the lead frame arranged facing each other, and for each of the plurality of circuit boards, It is possible to adopt a method of connecting an inner lead in which the metal pattern and the inner lead are laser welded.

[0026] As a result, high-throughput and highly accurate laser welding can be achieved.

[0027] In this case, the inner lead connection method can be such that the irradiation direction of the laser light is aligned with the direction in which the inner lead extends from the outer lead side toward the end side.

[0028] This allows for more stable laser welding.

[0029] In this case, the method for manufacturing a semiconductor device can include a step of joining the inner leads and the circuit board using the inner lead connection method described above.

[0030] This makes it possible to provide semiconductor devices with improved reliability.

[0031] In this case, the semiconductor device manufactured by the above-described method for manufacturing a semiconductor device can be used to manufacture an electrical device.

[0032] This allows us to provide electrical equipment with improved reliability.

[0033] In this case, the semiconductor device may be one manufactured by the above-described method for manufacturing a semiconductor device.

[0034] This results in a semiconductor device with improved reliability.

[0035] This disclosure also provides a method for connecting inner leads, in which the upper surface of a metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface is brought into contact with the lower surface of a lead frame having an inner lead having a lower surface that contacts the metal pattern on the circuit board at its end, and laser welding is performed by irradiating the inner lead from the upper surface side, wherein the irradiating motion is directed in one direction and performed in multiple steps for a single welding area.

[0036] This method of connecting inner leads allows for laser bonding of the inner leads to the circuit board's metal pattern with greater stability and strength by expanding the welding area while suppressing damage to the circuit board.

[0037] In this case, when the number of times is N times (where N≧2), the inner lead connection method can be used to superimpose the laser irradiation area of ​​the Nth time onto a portion of the laser irradiation area of ​​the N-1 time.

[0038] This allows for laser bonding of the metal patterns and inner leads of the circuit board with even greater stability and higher bonding strength by expanding the welding area while suppressing damage to the circuit board.

[0039] In this case, when the number of times is N times (where N≧2), the inner lead connection method can be used to separate the laser irradiation area of ​​the N-1th time the laser is irradiated while traveling and the laser irradiation area of ​​the Nth time the laser is irradiated while traveling in the direction of the laser being irradiated.

[0040] This allows for laser bonding of the metal patterns and inner leads of the circuit board with even greater stability and higher bonding strength by expanding the welding area while suppressing damage to the circuit board.

[0041] The present disclosure also provides a method for connecting an inner lead, comprising: bringing into contact the upper surface of a metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface, with the lower surface of a lead frame having an inner lead having a lower surface that contacts the metal pattern on the circuit board at its end, and laser welding by irradiating the inner lead from the upper surface side, wherein the laser irradiation area from which the laser beam is irradiated is a linearly extending area, and the laser beam is irradiated in one direction along the longitudinal direction of the laser irradiation area; and a second laser welding step in which the laser beam is irradiated in the other direction along the longitudinal direction so as to overlap a part of the first laser irradiation area of ​​the first laser welding step, wherein the irradiation in the second laser welding step is terminated before reaching the starting position of the first laser welding step.

[0042] This method of connecting inner leads allows for stable and high-strength laser bonding between the metal pattern on the circuit board and the inner leads.

[0043] The disclosure also provides a semiconductor device comprising a circuit board having a metal pattern, a semiconductor chip mounted on the circuit board, and a lead frame having inner leads welded to the upper surface of the metal pattern of the circuit board, wherein the weld marks in the weld area between the inner leads and the metal pattern include a terminal portion and a protrusion spaced apart from the terminal portion, and have at least one weld bead extending linearly in a top view, and having a plurality of at least one of the terminal portion and the protrusion.

[0044] Such a semiconductor device will have high bonding strength and improved reliability.

[0045] In this case, the semiconductor device may have a first weld bead and a second weld bead extending in the opposite direction to the first weld bead and partially overlapping the first weld bead, and the semiconductor device may have a terminal end of the first weld bead, a terminal end of the second weld bead, and a protrusion of the second weld bead located on the first weld bead.

[0046] This results in a semiconductor device with consistently high bonding strength and improved reliability.

[0047] In this case, the semiconductor device can have a first weld bead and a second weld bead that extends in the same direction as the first weld bead and partially overlaps with the first weld bead, and has a protrusion on the first weld bead, a terminal portion on the second weld bead and a protrusion on the second weld bead that is located on the first weld bead.

[0048] This results in a semiconductor device with consistently high bonding strength and improved reliability.

[0049] In this case, the semiconductor device may have a first weld bead and a second weld bead extending in the same direction as the first weld bead, the first weld bead and the second weld bead being separated, and the semiconductor device may have a protrusion of the first weld bead, an end portion of the first weld bead, a protrusion of the second weld bead, and an end portion of the second weld bead.

[0050] This results in a semiconductor device with consistently high bonding strength and improved reliability.

[0051] In this case, the semiconductor device can have a first weld bead and a second weld bead extending in the opposite direction to the first weld bead and partially overlapping the first weld bead, and the first weld bead has a protrusion, the second weld bead has a terminal end, and the second weld bead has a protrusion.

[0052] This results in a semiconductor device with consistently high bonding strength and improved reliability. [Effects of the Invention]

[0053] As described above, the inner lead connection method of this disclosure makes it possible to laser weld the circuit pattern on the circuit board and the inner lead with stable and high bonding strength. Furthermore, the semiconductor device of this disclosure has high bonding strength and is a semiconductor device with improved reliability. [Brief explanation of the drawing]

[0054] [Figure 1] This is a diagram illustrating the method of connecting the inner leads in this disclosure, and is an enlarged cross-sectional view of the joint. [Figure 2] These drawings illustrate the connection method of the inner lead and the shape of the pressing claws in this disclosure. [Figure 3] This is a drawing showing a semiconductor device that can be manufactured by applying the inner lead connection method described herein. [Figure 4] This diagram schematically illustrates laser irradiation when the angle of incidence of the laser to the irradiation surface is inclined from the perpendicular. [Figure 5] This diagram illustrates an example of connecting multiple inner leads on a single circuit board. [Figure 6] This diagram illustrates a method of performing laser welding on multiple circuit boards by using a galvanoscanning laser beam for irradiation. [Figure 7] This diagram illustrates a method of performing laser welding on multiple (three or more) circuit boards using a galvanoscanning laser beam path. [Figure 8] This drawing shows an example of tilting the receiving jig. [Figure 9] This diagram illustrates an example of using a lead frame with inner leads arranged in a grid-like pattern. [Figure 10]An example of a semiconductor device, an intelligent power module (top view), is shown. [Figure 11] This is a diagram illustrating an air conditioner as one embodiment of an electrical appliance. [Figure 12] This is a diagram showing a typical method for connecting inner leads. [Figure 13] This is a drawing illustrating a second embodiment of the inner lead connection method of the present disclosure. [Figure 14] This is a drawing illustrating a third embodiment of the inner lead connection method of the present disclosure. [Figure 15] This is a drawing illustrating a fourth embodiment of the inner lead connection method of the present disclosure. [Figure 16] This is a drawing illustrating a fifth embodiment of the inner lead connection method of the present disclosure. [Figure 17] This is a diagram illustrating the welding state in the depth direction of the fifth embodiment. [Figure 18] This diagram illustrates the state of the welded area as observed from above when laser welding is performed by irradiating it with a moving laser beam. [Figure 19] This is a diagram (top view) illustrating the welding area when laser welding is performed by irradiating a laser beam while moving. [Figure 20] This is a drawing (top view) showing an example of a semiconductor device in which the welded area has two terminal ends and one protrusion. [Figure 21] This is an observational photograph of a welded area having a weld mark with two terminal ends and one protrusion, viewed from above. [Figure 22] This is a drawing (top view) showing an example of a semiconductor device in which the welded area has one terminal end and two protrusions. [Figure 23] This is an observational photograph of a welded area having a weld mark with one terminal end and two protrusions, viewed from above. [Figure 24] This is a drawing (top view) showing an example of a semiconductor device in which the welded area has two terminal ends and two protrusions. [Figure 25]This is a drawing (top view) showing an example of a semiconductor device in which the welded area has one terminal end and two protrusions. [Figure 26] This is an observational photograph of a welded area having a weld mark with two terminal ends and one protrusion, viewed from above. [Modes for carrying out the invention]

[0055] The disclosure is described in detail below, but is not limited to this.

[0056] As described above, there was a need for an inner lead connection method that enables laser welding of the circuit pattern on the circuit board to the inner lead with stable and high bonding strength, and for a semiconductor device in which the circuit pattern on the circuit board and the inner lead are laser-welded with stable and high bonding strength, thereby improving reliability.

[0057] As a result of diligent study on the above issues, the Disclosers have found that a laser welding method can be performed to connect an inner lead to a circuit board, where a semiconductor chip is mounted on a circuit board having a metal pattern on its surface, and an inner lead having an inner lead with a lower surface that contacts the metal pattern on the circuit board at its end, by irradiating the inner lead with laser light from the upper surface side, wherein the upper surface of the metal pattern and the lower surface of the end of the inner lead are brought into contact, and a pressing jig equipped with a plurality of pressing claws for pressing the end of the inner lead against the upper surface of the metal pattern is used to press the end of the inner lead from above, and the laser light is irradiated in the region between the plurality of pressing claws from one pressing claw towards the other pressing claw, thereby laser welding the circuit pattern of the circuit board and the inner lead, and have completed this disclosure.

[0058] The Disclosers have also found that, in a method for connecting inner leads, the upper surface of a metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface is brought into contact with the lower surface of a lead frame equipped with an inner lead having a lower surface that contacts the metal pattern on the circuit board at its end, and laser welding is performed by irradiating the inner lead with laser light from the upper surface side, and by performing the irradiating motion in one direction multiple times for a single welding area, it is possible to laser bond the metal pattern on the circuit board and the inner lead with stable and high bonding strength while suppressing damage to the circuit board, and have completed this disclosure.

[0059] The Disclosers have also found that a laser welding method for connecting an inner lead, comprising bringing into contact the upper surface of a metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface, with the lower surface of a lead frame equipped with an inner lead having a lower surface that contacts the metal pattern on the circuit board at its end, and irradiating the inner lead with laser light from the upper surface side, the method comprising: a first laser welding step in which the laser irradiation area for irradiating the laser light is a linearly extending area and the laser light is irradiated in one direction along the longitudinal direction of the laser irradiation area; and a second laser welding step in which the laser light is irradiated in the other direction along the longitudinal direction so as to overlap a part of the first laser irradiation area of ​​the first laser welding step, wherein the irradiation in the second laser welding step is terminated before reaching the starting position of the first laser welding step, can stably laser-bond the metal pattern on the circuit board and the inner lead, and have completed the Disclosure.

[0060] The Disclosers have also found that a semiconductor device comprising a circuit board having a metal pattern, a semiconductor chip mounted on the circuit board, and a lead frame having inner leads welded to the upper surface of the metal pattern on the circuit board, wherein the weld marks in the weld area between the inner leads and the metal pattern include a terminal portion and a protrusion spaced apart from the terminal portion, and have at least one weld bead extending linearly in a top view, and having a plurality of at least one of the terminal portion and the protrusion, allows for laser welding of the circuit pattern on the circuit board and the inner leads with high bonding strength, resulting in a semiconductor device with improved reliability, and have completed this disclosure.

[0061] The following explanation will be given with reference to the drawings.

[0062] [Method of connecting inner leads] Next, the method for connecting the inner leads related to this disclosure will be described. For information on the components that make up the semiconductor device, please refer to the description of the semiconductor device described later.

[0063] (First embodiment) Figure 1 is a diagram illustrating the inner lead connection method of this disclosure, showing an enlarged cross-sectional view of the joint. The inner lead connection method according to this disclosure is an inner lead connection method in which a laser beam L is irradiated from the upper surface side of the inner lead 14 to a lead frame 15 having an inner lead 14 having a metal pattern 11 on the surface of a circuit board 13 on which a semiconductor chip 10 is mounted, and an inner lead 14 having a lower surface that contacts the metal pattern 11 of the circuit board 13 at its end 14A, and the two are laser welded together. Chip mounting may be performed after laser welding.

[0064] As shown in Figure 1, the upper surface of the metal pattern 11 and the lower surface of the end 14A of the inner lead are brought into contact, and the end 14A of the inner lead is pressed from above using a pressing jig 20 equipped with multiple pressing claws 21A and 21B for pressing the end 14A of the inner lead against the upper surface of the metal pattern 11. Then, a laser beam L is irradiated (direction S in the figure) from one pressing claw 21A to the other pressing claw 21B in the region between the multiple pressing claws 21A and 21B, thereby laser welding the metal pattern 11 of the circuit board 13 and the inner lead 14.

[0065] By irradiating a laser beam L between multiple pressing claws 21A and 21B that press the end 14A of the inner lead from above, the metal pattern 11 of the circuit board 13 and the inner lead 14 are laser-welded, enabling stable and high-strength laser bonding of the metal pattern 11 of the circuit board 13 and the inner lead 14. In the example shown in Figure 1, the circuit board 13 is placed on a receiving jig 30 for laser irradiation, but the method is not limited to this.

[0066] Figure 2 shows a schematic diagram (top view) of a case where multiple inner leads 14 are joined on a single circuit board 13, and a preferred example of a pressing claw 21 (cross-sectional view). As shown in Figure 2, when laser welding multiple inner leads 14 (forming multiple welding areas), a pressing jig 20 equipped with pressing claws 21A and 21B that press both ends of the laser welding area of ​​each inner lead 14 is used to press both ends of the laser welding area from above the circuit board 13 placed on the receiving jig 30, and laser light can be irradiated onto each laser welding area. If the pressing jig 20 has the same external dimensions as the receiving jig 30, it can be easily stacked and used.

[0067] Furthermore, the shape of the pressing claw 21 is preferably such that force is applied vertically from above in order to sufficiently press the end 14A of the inner lead against the upper surface of the metal pattern 11 (see upper diagram in Figure 2).

[0068] The laser irradiation method is not particularly limited as long as it allows for mobile irradiation, but it is preferable to perform mobile irradiation of the laser beam using a galvanoscan method. This allows for high-throughput and high-precision laser bonding.

[0069] The semiconductor chip 10 is not particularly limited. For example, it may be a power chip such as a transistor or diode that handles high power, or a power chip and a control chip such as a control IC that does not handle as much power as the power chip may be placed at different positions on the circuit board. These may be fixed on the circuit board 13 by soldering or conductive adhesive.

[0070] Furthermore, the circuit board 13 is not particularly limited as long as it has a metal pattern 11 on its surface. For example, a substrate having metal patterns 11 on both sides of a ceramic substrate 10 as shown in Figure 3, or more specifically, a DBC substrate (Direct Bonded Copper substrate) in which copper material is directly bonded to a ceramic insulating substrate, can be used.

[0071] In the inner lead connection method of this disclosure, laser irradiation is preferably performed by galvanoscanning laser beam travel irradiation. For example, laser welding systems using galvanoscanning are known, as described in Patent Documents 3 and 4. In galvanoscanning laser beam travel irradiation, the laser moves across the irradiation area by moving a mirror that reflects the laser beam, so the processing speed is very high and laser irradiation (welding) can be performed with high precision.

[0072] The laser used for laser irradiation in the inner lead connection method of this disclosure is not particularly limited as long as it is capable of welding the metal pattern and the inner lead. It may be a single-wavelength laser beam, or a first laser beam and a second laser beam with a longer wavelength than the first laser beam may be irradiated simultaneously (superimposed irradiation).

[0073] In the case of superimposed irradiation, the area near the surface of the inner lead is the heating region of the first laser beam, and a deeper area is the heating region of the second laser beam. It is even more preferable to use an ultraviolet (UV) laser or a blue laser as the first laser beam and an infrared (IR) laser as the second laser beam. With such a combination, the preheating effect of the first laser beam and the processing effect of the second laser beam are more stably exhibited when joining metal materials.

[0074] Ultraviolet (UV) and blue lasers have different light absorption rates in metal materials compared to infrared lasers. For example, when the metal material is copper (Cu), the absorption rate of a blue laser is approximately 65%, while the absorption rate of an infrared laser is approximately 5% or less. Therefore, by irradiating the surface of the metal material (inner lead) with UV or blue lasers to heat it, and then assisting the heating with an infrared laser, melting of the joint between the inner lead and the metal pattern can be achieved more efficiently and stably. In such laser irradiation, the melting related to the joint is essentially carried out by the infrared laser. In other words, UV and blue lasers contribute to stabilizing heating and melting, and prevent the molten pool from solidifying too rapidly.

[0075] When performing laser welding, the travel speed of the laser beam L is preferably about 200 to 500 mm / sec. Furthermore, the laser irradiation distance is preferably about 0.5 to 1.5 mm. This is because it allows for high processing throughput and stable joining.

[0076] Furthermore, in galvanoscan laser irradiation, the laser beam is moved by moving a mirror that reflects the laser light, so the positional relationship between the irradiated object, the circuit board and inner leads, and the laser head of the laser irradiator remains unchanged. Therefore, the angle of incidence of the laser to the irradiation surface is not perpendicular, but tilted within a predetermined range. Figure 4 is a schematic diagram showing laser irradiation when the angle of incidence of the laser to the irradiation surface is tilted from perpendicular. Here, the center of laser irradiation in galvanoscan laser irradiation (position vertically downward from the laser irradiator 25) is defined as the laser irradiation center point 40. Both Figures 4(A) and (B) show the case where the laser irradiator 25 is located to the upper right of the circuit board, and the laser irradiation center point 40 is located on the right side of the figure. Figure 4(A) shows the case where the laser beam L is irradiated from the pressing claw 21A on the side closer to the laser irradiation center point 40, towards the other pressing claw 21B on the side further from the laser irradiation center point 40 (direction S in the figure). Figure 4(B) shows the case where the laser beam L is irradiated from the pressing claw 21B on the side farther from the laser irradiation center point 40, towards the other pressing claw 21A on the side closer to the laser irradiation center point 40 (direction S in the figure). As shown in Figure 4, in both cases (A) and (B), it is necessary to irradiate the laser in a way that avoids the pressing claw 21A.

[0077] When the inventors investigated laser welding between multiple pressing claws, they found that, as shown in Figure 4, a protrusion (blowing region) 43 is formed on the surface of the inner lead near the starting point of the traveling irradiation. In cases where the incident angle of the laser with respect to the irradiation surface is inclined, such as in galvanoscan laser irradiation, it is necessary to irradiate the laser in a way that avoids the pressing claws 21A. Therefore, in the vicinity of the pressing claws 21A that are closer to the laser irradiation center point 40, it is unavoidable that a region 45 remains where laser irradiation is not possible due to the pressing claws 21A acting as a three-dimensional obstruction.

[0078] As shown in Figure 4(B), when the laser beam L is irradiated from the pressing claw 21B on the side farther from the laser irradiation center point 40 toward the other pressing claw 21A on the side closer to the laser irradiation center point 40, the laser irradiation must be started from a position slightly away from the pressing claw 21B in order to leave a formation area for the convex portion (blowing region) 43. On the other hand, as shown in Figure 4(A), if the laser beam L is irradiated from the pressing claw 21A on the side closer to the laser irradiation center point 40 toward the other pressing claw 21B on the side further from the laser irradiation center point 40, a protrusion (blowout region) 43 will be formed in the region 45 where laser irradiation is not possible near the pressing claw 21A on the side closer to the laser irradiation center point 40. As a result, laser irradiation can be performed up to the very vicinity of the pressing claw 21B on the side further from the laser irradiation center point 40.

[0079] Thus, in the case of Figure 4(A), it is possible to make the laser irradiation area larger (L1>L2) than in the case of Figure 4(B), and laser welding with higher joint strength can be performed. In this way, it is preferable to irradiate the laser beam L from the pressing claw 21A on the side closer to the laser irradiation center point 40 toward the other pressing claw 21B on the side further from the laser irradiation center point 40.

[0080] Figure 5 shows an example of joining multiple inner leads on a single circuit board 13. Figure 5(A) is a cross-sectional view taken along line ab in the top view of Figure 5(B). For simplicity, the pressing claws 21 (21A, 21B) shown in Figure 2 are not shown. As explained based on Figure 2, using a pressing jig 20 equipped with pressing claws 21A, 21B, both ends of the laser welding area are pressed from above the circuit board 13 placed on the receiving jig 30. After setting the position of the receiving jig 30 and / or the laser beam irradiator 25 so that the laser irradiation center point 40 is in an appropriate position near the circuit board 13, the laser beam can be irradiated onto each laser welding area as shown in Figure 5.

[0081] Next, we will describe the case where laser welding is performed on multiple circuit boards using a galvanoscanning laser beam. As shown in Figure 6, multiple circuit boards 13 are placed on a receiving jig 30, and the positions of the laser beam irradiator 25 and the receiving jig 30 are adjusted so that the laser irradiation center point 40 is located between the multiple circuit boards 13. By irradiating each of the laser welding areas of the multiple circuit boards 13 with the laser beam L, the metal pattern 11 and the inner lead 14 can be laser welded. This allows for laser joining with higher throughput and higher precision. For simplicity, the pressing jig 20 is not shown in Figure 6.

[0082] (Modified version of the first embodiment) Further embodiments will be described using Figure 7-9. In Figure 7-9, the focus is on the position of the circuit board 13, so lead frames and metal patterns are not shown. Also, in Figures 7 and 8, (A) and (B) respectively, the left side is a top view and the right side is a side view.

[0083] Figure 6 shows a configuration in which two circuit boards are placed on the receiving jig 30. However, as shown in Figure 7, three or more circuit boards 13 may be placed on the receiving jig 30, and laser welding may be performed on each pair of circuit boards by intermittently moving the receiving jig and / or the laser beam irradiator so that the laser irradiation center point 40 is located between the pair of circuit boards 13. For example, in Figure 7, the positional relationship between the laser irradiator and the receiving jig 30 is adjusted so that the laser irradiation center point 40A is the laser irradiation center point, and laser welding is performed on circuit boards 13A and 13B. Then, it is adjusted so that the laser irradiation center point 40B is the laser irradiation center point, and laser welding is performed on circuit boards 13C and 13D. In this way, the laser irradiation center point is intermittently moved from 40A → 40B → 40C → 40D, and laser welding can be performed on circuit boards 13A and 13B, 13C and 13D, 13E and 13F, and 13G and 13H. The same operation is shown in Figures 8 and 9.

[0084] Furthermore, in galvanoscanning laser beam irradiation, it is preferable to irradiate the laser beam L in a direction aligned with the direction in which the inner lead extends from the outer lead side to the end side, as shown in the lower joint in the right diagram of Figure 7(A) and the right joint in Figure 7(B). If the irradiation direction of the laser beam L is set in a direction opposite to the direction in which the inner lead extends from the outer lead side to the end side, as shown in the upper joint in the right diagram of Figure 7(A), there is a risk that the laser beam L will penetrate the welding area at the bend of the inner lead (dotted arrow), damaging the inner lead, causing it to deviate from the metal pattern, and making welding impossible. In contrast, if the laser beam L is irradiated in a direction aligned with the direction in which the inner lead extends from the outer lead side to the end side, as shown in the lower joint in the right diagram of Figure 7(A) and the right joint in Figure 7(B), more stable laser bonding can be achieved. In particular, as shown in Figure 7(B), arranging the pair of circuit boards 13 so as to be point-symmetric with respect to the laser irradiation center point 40 is preferable because it allows the direction of the inner lead and laser irradiation to be aligned at all welding points, as shown in the right-hand diagram of Figure 7(B).

[0085] As shown in Figure 8, it is also preferable to tilt the receiving jig 30 with respect to the direction of the circuit boards located on both sides of the laser irradiation center point 40 after the circuit boards 13 have been placed. The receiving jig 30 can be made of, for example, an aluminum plate and have a recess that is slightly larger than the circuit boards 13. In this case, even if there is variation in the position of the circuit boards 13 placed on the receiving jig 30 as shown in Figure 8(A), tilting the receiving jig 30 allows the placed circuit boards to be aligned to one side as shown in Figure 8(B).

[0086] Furthermore, even in cases where the laser irradiation distances for each of the circuit boards arranged opposite each other are different (P2 > P1), as shown in the right-hand diagram of Figure 8(A), it is possible to make the laser irradiation distances approximately equal (P2 ≈ P1) by tilting the receiving jig 30, as shown in the right-hand diagram of Figure 8(B).

[0087] Furthermore, as shown in Figure 9, it is preferable to prepare a lead frame 15 for each of the multiple circuit boards 13 placed on the receiving jig 30, which is equipped with inner leads 14 in which multiple lead patterns are arranged in a grid strip shape, and to adjust the positions of the laser beam irradiator and the receiving jig 30 so that the lead patterns of the lead frames 15 are facing each other, and the laser irradiation center point 40 is located at the center between the lead patterns of the facing lead frames 15, thereby laser welding the metal pattern 11 and the inner leads 14 to each of the multiple circuit boards 13. This allows for laser bonding with higher throughput and higher precision.

[0088] Further embodiments will be described. The following description is a variation of the inner lead connection method described above. Therefore, repeated explanations will be omitted, but it goes without saying that the matters described so far are applicable.

[0089] (Second embodiment) First, when laser welding the metal pattern and inner lead of a circuit board using a pressing jig as described above, the laser irradiation can be divided into multiple passes in the order of Figure 13(A)→(B). When performing laser irradiation over a distance, the laser output may be gradually reduced at the end of the irradiation to prevent void formation. In this case, the welding area at the end of the irradiation may be narrower than at the start of the irradiation. Also, if the laser irradiation distance is long, the total amount of heat will increase, which may cause cracks in circuit boards such as DBC boards.

[0090] Therefore, by performing multiple irradiation passes as in this embodiment, the welding area can be expanded, and cracks in circuit boards such as DBC substrates can be prevented. As a result, by expanding the welding area while suppressing damage to the circuit board, the metal pattern and inner leads of the circuit board can be laser-bonded more stably and with higher bonding strength.

[0091] (Modified version of the second embodiment) As described above, when multiple laser irradiations are performed, the laser irradiation areas of the multiple irradiations may be superimposed. In other words, if the number of irradiations is N (where N≧2), the laser irradiation area of ​​the Nth irradiation can be superimposed on a portion of the laser irradiation area of ​​the N-1th irradiation.

[0092] Furthermore, when performing multiple laser irradiations as described above, the laser irradiation areas of the multiple irradiations may be arranged so as not to overlap. In other words, if the number of irradiations is N (where N≧2), the laser irradiation area of ​​the (N-1)th irradiation and the laser irradiation area of ​​the Nth irradiation can be separated in the direction of the irradiation.

[0093] Furthermore, when performing multiple laser beam irradiations, the direction of the irradiation can be switched to the opposite direction. Specifically, by setting S1 and S2 in Figure 13 to opposite directions, it is possible to perform laser beam irradiation from one pressing claw towards the other, followed by further irradiation from the other pressing claw towards the first pressing claw.

[0094] The upper limit of the number of times (N times) mentioned above is not particularly limited. The upper limit of the number of times can be set appropriately depending on the size of the laser irradiation area, etc. For example, N can be 10, 5, 3, 2, etc.

[0095] According to the inner lead connection method described above, by expanding the welding area while suppressing damage to the circuit board, it is possible to laser bond the metal pattern of the circuit board and the inner lead with even greater stability and higher bonding strength.

[0096] (Third embodiment) As described above, a protrusion (blowout region) 43 is formed near the starting position (starting point) of the laser beam's travel and irradiation. When the protrusion (blowout region) 43 comes into contact with the pressing claw and the welded metal such as copper hardens, the pressing claw and the inner lead may become joined together. To prevent this, it is necessary to ensure a sufficient distance between the starting position of the laser beam's travel and irradiation and the pressing claw, but this also results in a narrower laser beam irradiation range.

[0097] Therefore, when using a pressing jig equipped with two pressing claws, and when irradiating a laser beam between the two pressing claws, it is preferable to set the starting position when irradiating a laser beam from one pressing claw in the direction S1 toward the other pressing claw (Figure 14(A)) to approximately the midpoint between the two pressing claws, and the starting position when irradiating a laser beam from the other pressing claw in the direction S2 toward the first pressing claw (Figure 14(B)) to approximately the same position as the starting position when irradiating a laser beam from one pressing claw in the direction S1 toward the other pressing claw. As a result, the convex portion (blowing area) 43 is formed near the midpoint between the two pressing claws, thus suppressing contact between the convex portion (blowing area) 43 and the pressing claws. Moreover, the irradiation range (welding range) of the laser beam can be made wider. As a result, it is possible to laser bond the metal pattern of the circuit board and the inner lead with higher joint strength and more stably while suppressing damage to the circuit board. Furthermore, it is possible to repeat the irradiation process shown in Figures 14(A) and 14(B) multiple times.

[0098] Furthermore, "approximately the same position" includes not only cases where both are in exactly the same position, but also cases where the starting positions of the laser beams are offset, but the weld marks when the laser beam is directed toward S1 and the weld marks when the laser beam is directed toward S2 are not separated. Additionally, "approximately the intermediate position" includes a range centered on the position that divides the space between the two pressing claws in half, with a range of 25% of the distance between the two pressing claws in the direction of one pressing claw and 25% of the distance between the two pressing claws in the direction of the other pressing claw.

[0099] Next, another embodiment of the inner lead connection method according to this disclosure will be described. The following description is a modification of the inner lead connection method described so far, and is an embodiment in which the use of the pressing jig 20 is not required.

[0100] (Fourth embodiment) This embodiment describes a method for connecting inner leads by bringing the upper surface of a lead frame, which has an inner lead with a metal pattern on its surface and on which a semiconductor chip is mounted, into contact with the lower surface of the inner lead, which has a lower surface that contacts the metal pattern on the circuit board at its end, and then laser welding by irradiating the inner lead from the upper surface side. In this method, as shown in Figure 15, the irradiating motion is directed in one direction and performed multiple times (Figures 15(A) and 15(B)) for each weld.

[0101] When welding is performed by laser irradiation, the laser output may be gradually reduced at the end of the irradiation path to prevent void formation. In this case, the welding area at the end of the irradiation path will be narrower than at the beginning of the irradiation path. Also, if the laser irradiation distance is long, the total amount of heat will increase, which may cause cracks in circuit boards such as DBC substrates.

[0102] Therefore, by dividing the laser irradiation into multiple passes in the same direction S1 and S2, as in this embodiment (Figure 15(A) → Figure 15(B)), the welding area can be expanded, and cracks in circuit boards such as DBC substrates can be prevented. As a result, the metal pattern of the circuit board and the inner leads can be laser-bonded with greater stability and higher bonding strength. The number of passes (N passes) when the laser irradiation is performed multiple times in one direction is not particularly limited. The number of passes can be set appropriately depending on the size of the laser irradiation area, etc., for example, N can be 10, 5, 3, 2, etc.

[0103] (Modification of the fourth embodiment) In this embodiment as well, the laser irradiation areas of multiple irradiation sessions may be superimposed. In other words, if the number of sessions is N (where N≧2), the laser irradiation area of ​​the Nth irradiation session can be superimposed on a portion of the laser irradiation area of ​​the N-1th irradiation session.

[0104] Furthermore, the laser irradiation areas of multiple irradiation sessions may be arranged so as not to overlap. In other words, if the above multiple sessions are N (where N≧2), the laser irradiation area of ​​the (N-1)th irradiation session and the laser irradiation area of ​​the Nth irradiation session can be separated in the direction of the irradiation session.

[0105] The upper limit of the above number of times (N times) is not particularly limited. It can be set appropriately depending on the size of the laser irradiation area, etc., but for example, N can be 10, 5, 3, 2, etc.

[0106] This method of connecting inner leads allows for laser bonding of the inner leads to the circuit board's metal pattern with greater stability and strength by expanding the welding area while suppressing damage to the circuit board.

[0107] (Fifth embodiment) A fifth embodiment of an inner lead connection method is described, in which the upper surface of a metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface is brought into contact with the lower surface of a lead frame equipped with an inner lead that has a lower surface that contacts the metal pattern on the circuit board at its end, and laser welding is performed by irradiating a laser beam from the upper surface side of the inner lead.

[0108] In the inner lead connection method according to this embodiment, as shown in Figure 16, the laser irradiation area on which the laser beam is irradiated is a linearly extending area, and the method includes a first laser welding step in which the laser beam is irradiated in one direction along the longitudinal direction of the laser irradiation area, and a second laser welding step in which the laser beam is irradiated in the other direction along the longitudinal direction so as to overlap a part of the first laser irradiation area of ​​the first laser welding step, and the irradiation in the second laser welding step is terminated before reaching the starting position of the first laser welding step.

[0109] When welding is performed by laser irradiation, the laser output is sometimes gradually reduced at the end of the irradiation to prevent void formation. In this case, as shown in Figure 17(A), the welding area at the end of the irradiation may be narrower than at the start of the irradiation. Also, if the laser irradiation distance is long, the total amount of heat increases, which may cause cracks in circuit boards such as DBC substrates. Therefore, as shown in Figures 16 and 17, the directions S1 and S2 of the laser irradiation for the first and second laser welding processes are reversed, and the laser irradiation area of ​​the second laser welding process is superimposed on a part of the laser irradiation area of ​​the first laser welding process. Then, the irradiation in the second laser welding process is terminated before reaching the starting position of the first laser welding process. By performing the first and second laser welding processes in this way, the welding area can be efficiently expanded (Figure 17(B)), and cracks in circuit boards such as DBC substrates can be prevented. As a result, the metal pattern on the circuit board and the inner leads can be laser-bonded with greater stability and higher bonding strength.

[0110] [Manufacturing method for semiconductor devices] Furthermore, the method for connecting inner leads according to this disclosure provides a method for manufacturing a semiconductor device that includes a step of joining inner leads to a circuit board. According to the method for manufacturing a semiconductor device according to this disclosure, the metal pattern of the circuit board and the inner leads can be laser-bonded with stable and high bonding strength, making it possible to manufacture a highly reliable semiconductor device. Figure 3 shows a semiconductor device 100 that can be manufactured by the method for manufacturing a semiconductor device according to this disclosure. As shown in Figure 3, the semiconductor device 100 comprises a circuit board 13 having a metal pattern 11 on its surface, a semiconductor chip 10 mounted on the circuit board 13, a lead frame 15 including inner leads 14 whose bonding regions at the ends are connected to the circuit board 13, and a molding resin 16 that resin-encapsulates the semiconductor chip 10 and the lead frame 15.

[0111] [Semiconductor device] The semiconductor device according to this disclosure will now be described. As shown in Figure 3, the semiconductor device according to this disclosure comprises a circuit board 13 having a metal pattern, a semiconductor chip 10 mounted on the circuit board 13, and a lead frame 15 having inner leads 14 welded to the upper surface of the metal pattern 11 of the circuit board 13. In the semiconductor device according to this disclosure, the weld marks in the weld area between the inner leads and the metal pattern include a terminal portion and a protrusion separated from the terminal portion, and have at least one weld bead that extends linearly when viewed from above.

[0112] As shown in Figure 1 of the first embodiment described above, when a laser beam is irradiated once in one direction, a weld mark like that shown in Figure 18 can be observed when the welding area is viewed from above. Figure 19 shows a conceptual diagram of the weld mark 50. Both Figures 18 and 19 show the case when the laser is irradiated from right to left in the figure. As already explained, a convex portion (blowing area) 43 is formed on the surface of the inner lead 14 near the starting position 53 of the irradiated portion. The convex portion 43 is formed on the opposite side of the direction of the irradiated portion from the starting position of the irradiated portion of the laser. In addition, a weld bead 51 is formed in the area where the laser irradiated. As shown in Figure 19, when the laser is irradiated, a weld bead 51 having a wavy pattern is formed in which the tips of the waves overlap so that they point in the opposite direction of the direction of the irradiated portion of the laser. And a terminal portion 55 is formed on the opposite side of the starting position 53 of the welding area. Thus, the terminal portion 55 and the convex portion 43 are separated. Note that the direction of extension of the weld bead can be determined and defined from the direction of the waves in the wavy pattern of the weld mark.

[0113] One embodiment of the semiconductor device according to the present disclosure has at least one weld bead that extends linearly when viewed from above, and has a plurality of terminal portions and at least one of convex portions.

[0114] For example, it may have two terminal portions 55A, 55B and one protrusion 43. More specifically, as shown in the conceptual diagram of Figure 20 and the observation photograph of Figure 21, the weld mark of the weld area may have a first weld bead 51A and a second weld bead 51B that extends in the opposite direction to the first weld bead 51A and partially overlaps with the first weld bead 51A, and may have a terminal portion 55A of the first weld bead 51A, a terminal portion 55B of the second weld bead 51B and a protrusion 43B of the second weld bead 51B located on the first weld bead 51A. Such a semiconductor device according to the present disclosure has stable and high bonding strength and improved reliability.

[0115] A semiconductor device having the welding area shown in Figures 20 and 21 can be manufactured, for example, in a semiconductor device manufacturing method that includes a step of joining inner leads to a circuit board by an inner lead connection method as shown in Figure 14, by superimposing a second irradiation on a part of the first irradiation area.

[0116] Furthermore, in yet another embodiment of the semiconductor device according to this disclosure, as shown in the conceptual diagram of Figure 22 and the observation photograph of Figure 23, the weld mark 50B of the weld area may have a first weld bead 51A and a second weld bead 51B that extends in the same direction as the first weld bead 51A and partially overlaps with the first weld bead 51A, and may have a protrusion 43A of the first weld bead 51A, an end portion 55B of the second weld bead 51B and a protrusion 43B of the second weld bead 51B located on the first weld bead 51A.

[0117] A semiconductor device having a welded area as shown in Figures 22 and 23 can be manufactured in a semiconductor device manufacturing method that includes a step of joining inner leads to a circuit board using the inner lead connection method shown in Figures 13 and 15, by superimposing a second irradiation on a portion of the first irradiation. Such a semiconductor device according to this disclosure has a more stable and higher bonding strength and improved reliability.

[0118] Furthermore, in yet another embodiment of the semiconductor device according to the present disclosure, as shown in the conceptual diagram of Figure 24, the weld mark 50C of the weld area may have a first weld bead 51A and a second weld bead 51B extending in the same direction as the first weld bead 51A, the first weld bead 51A and the second weld bead 51B being separated, and the first weld bead 51A may have a protrusion 43A, an end portion 55A, the second weld bead 51B may have a protrusion 43B, and the second weld bead 51B may have an end portion 55B.

[0119] A semiconductor device having a welded area as shown in Figure 24 can be manufactured by a semiconductor device manufacturing method that includes a step of joining the inner leads to the circuit board using the inner lead connection method shown in Figures 13 and 15. Such a semiconductor device according to this disclosure has a more stable and higher bonding strength and improved reliability.

[0120] Furthermore, in yet another embodiment of the semiconductor device according to the present disclosure, as shown in the conceptual diagram of Figure 25, the weld mark 50D of the weld area may have a first weld bead 51A and a second weld bead 51B that extends in the opposite direction to the first weld bead 51A and partially overlaps with the first weld bead 51A, and the second weld bead 51B may have a protrusion 43A of the first weld bead 51A and a terminal portion 55B of the second weld bead 51B.

[0121] A semiconductor device having a welded area as shown in Figure 25 can be manufactured in a semiconductor device manufacturing method that includes a step of joining inner leads to a circuit board using the inner lead connection method shown in Figure 16, by adjusting the superposition of the first and second irradiation areas. Such a semiconductor device according to this disclosure has a more stable and higher bonding strength and improved reliability.

[0122] Furthermore, in yet another embodiment of the semiconductor device according to this disclosure, as shown in the observation photograph in Figure 26, the weld marks in the weld area may have a first weld bead 51A and a second weld bead 51B that extends in the opposite direction to the first weld bead 51A and partially overlaps with the first weld bead 51A, and may have an end portion 55A of the first weld bead 51A, an end portion 55B of the second weld bead 51B and a protrusion 43B of the second weld bead 51B. Such a semiconductor device according to this disclosure has a more stable and higher bonding strength and improved reliability.

[0123] Figure 10 shows an example of an intelligent power module (IPM) 200, which is a specific example of a semiconductor device. In the example in Figure 10, multiple semiconductor chips 10 are provided on a DBC substrate. The method of connecting the inner leads and metal patterns described above can be suitably applied to the manufacture of an IPM 200 as shown in Figure 10.

[0124] [Manufacturing methods for electrical equipment] Furthermore, a method for manufacturing electrical equipment can be provided for manufacturing electrical equipment using a semiconductor device manufactured by the semiconductor device manufacturing method of this disclosure. The semiconductor device 100 described above can be applied to electrical equipment. By using a semiconductor device with improved reliability and reduced cost, it contributes to improving the reliability and reducing the cost of electrical equipment. With such electrical equipment, the cost of the electrical equipment itself is also reduced due to the cost reduction of the semiconductor device. The electrical equipment is not particularly limited, but in particular, the example of the semiconductor device (IPM) 200 described above can be suitably applied as a small high-voltage three-phase motor driver to electrical equipment for driving compressors in air conditioners, refrigerators, etc.

[0125] Figure 11 illustrates an air conditioner 300 as one embodiment of an electrical device. The air conditioner 300 consists of an indoor unit 310 and an outdoor unit 320, each equipped with a fan motor 311, 321, a compressor 322, and an IPM 200 electrical device. The IPM 200 should be of a specification suitable for driving each motor and compressor. According to the manufacturing method of electrical devices of this disclosure, highly reliable electrical devices can be manufactured.

[0126] As detailed above, the inner lead connection method of this disclosure enables laser bonding of the metal pattern of the circuit board and the inner lead with stable and high bonding strength.

[0127] This specification includes the following embodiments: [1]: A method for connecting an inner lead, comprising laser welding an inner lead to a lead frame having an inner lead having a lower surface that contacts the metal pattern on the surface of a circuit board on which a semiconductor chip is mounted, by irradiating the inner lead with a laser beam from the upper surface side, The upper surface of the metal pattern and the lower surface of the end of the inner lead are brought into contact. Using a pressing jig equipped with a plurality of pressing claws for pressing the end of the inner lead against the upper surface of the metal pattern, the end of the inner lead is pressed from above. A method for connecting an inner lead, comprising irradiating the region between the plurality of pressing claws with the laser beam in the direction from one of the pressing claws to the other, thereby laser welding the metal pattern of the circuit board to the inner lead. [2]: A method for connecting the inner lead of [1] above, which performs the aforementioned traveling irradiation multiple times. [3]: The method for connecting the inner lead in [2] above, wherein, when the number of times is N times (however, N≧2), the laser irradiation area of ​​the Nth traveling irradiation is superimposed on a part of the laser irradiation area of ​​the N-1th traveling irradiation. [4]: A method for connecting the inner leads of [2] above, wherein, when the number of times is N times (however, N≧2), the laser irradiation area of ​​the N-1th time traveling irradiation and the laser irradiation area of ​​the Nth time traveling irradiation are separated in the direction of traveling irradiation. [5]: The method for connecting the inner lead according to [1], wherein, following the traveling irradiation, the laser beam is further irradiated from the other pressing claw toward the one pressing claw. [6]: Using the pressing jig equipped with the two pressing claws, The starting position when the laser beam is projected from one of the pressing claws toward the other pressing claw is set to approximately the midpoint between the two pressing claws. The inner lead connection method of [5] described above, wherein the starting position when the laser beam is irradiated from the other pressing claw toward the one pressing claw is approximately the same as the starting position when the laser beam is irradiated from the one pressing claw toward the other pressing claw. [7]: A method for connecting the inner leads of [1], [2], [3], [4], [5] or [6] above, wherein the traveling irradiation of the laser beam is performed in a galvanoscan manner. [8]: A method for connecting the inner leads of the [7] described above, wherein the pressing claw on the side closer to the laser irradiation center point in the galvanoscanning laser irradiation travels and irradiates laser light in the direction of the other pressing claw on the side further from the laser irradiation center point. [9]: The inner lead connection method according to [7] or [8] above, wherein a plurality of the circuit boards are placed on a receiving jig, and the positions of the laser beam irradiator and the receiving jig are adjusted so that the laser irradiation center point is located between the plurality of circuit boards, and the metal pattern and the inner lead are laser welded to each of the plurality of circuit boards.

[10] : The inner lead connection method of [9], wherein for each of the plurality of circuit boards placed on the receiving jig, a lead frame is prepared which has an inner lead having a plurality of lead patterns arranged in a grid strip shape, the lead patterns of the lead frame are placed facing each other, and the positions of the laser beam irradiator and the receiving jig are adjusted so that the laser irradiation center point is located at the center between the lead patterns of the facing lead frames, and the metal pattern and the inner lead are laser welded to each of the plurality of circuit boards.

[11] : A method for connecting an inner lead according to [8], [9], or

[10] , wherein the direction of irradiation of the laser beam is in a direction along the direction in which the inner lead extends from the outer lead side toward the end side.

[12] : A method for manufacturing a semiconductor device, comprising the step of joining the inner leads to the circuit board by the inner lead connection method described in [1], [2], [3], [4], [5], [6], [7], [8], [9],

[10] , or

[11] above.

[13] : A method for manufacturing electrical equipment using a semiconductor device manufactured by the method for manufacturing a semiconductor device described in

[12] above.

[14] : A semiconductor device manufactured by the semiconductor device manufacturing method described in

[12] above.

[15] : A method for connecting an inner lead, comprising bringing into contact the upper surface of the metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface, and the lower surface of a lead frame having an inner lead having a lower surface that contacts the metal pattern on the circuit board at its end, and irradiating the inner lead with laser light from the upper surface side to laser weld, A method for connecting inner leads, in which the aforementioned traveling irradiation is directed in one direction and performed multiple times on a single weld joint.

[16] : The method for connecting the inner lead in

[15] above, wherein, when the number of times is N times (however, N≧2), the laser irradiation area of ​​the Nth time traveling irradiation is superimposed on a part of the laser irradiation area of ​​the N-1 time traveling irradiation.

[17] : A method for connecting the inner leads of

[15] , wherein, when the number of times is N times (however, N≧2), the laser irradiation area of ​​the N-1th time traveling irradiation and the laser irradiation area of ​​the Nth time traveling irradiation are separated in the direction of traveling irradiation.

[18] : A method for connecting an inner lead, comprising bringing into contact the upper surface of the metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface, with the lower surface of a lead frame having an inner lead having a lower surface that contacts the metal pattern on the circuit board at its end, and laser welding by irradiating a laser beam from the upper surface side of the inner lead, The laser irradiation area on which the laser beam is irradiated is a linearly extending region, and the laser welding process includes a first laser welding process in which the laser beam is irradiated in one direction along the longitudinal direction of the laser irradiation area, and a second laser welding process in which the laser beam is irradiated in the other direction along the longitudinal direction so as to overlap a part of the first laser irradiation area of ​​the first laser welding process. A method for connecting an inner lead, wherein the traveling irradiation in the second laser welding process is terminated before reaching the starting position of the first laser welding process.

[19] : A semiconductor device comprising a circuit board having a metal pattern, a semiconductor chip mounted on the circuit board, and a lead frame having inner leads welded to the upper surface of the metal pattern of the circuit board, The weld marks in the weld area between the inner lead and the metal pattern include a terminal portion and a protrusion separated from the terminal portion, and have at least one weld bead that extends linearly when viewed from above. A semiconductor device having a plurality of terminal portions and a plurality of protrusions.

[20] : The semiconductor device according to

[19] , having a first weld bead and a second weld bead extending in the opposite direction to the first weld bead and partially overlapping the first weld bead, wherein the semiconductor device has a terminal portion of the first weld bead, a terminal portion of the second weld bead, and a protrusion of the second weld bead located on the first weld bead.

[21] : The semiconductor device according to

[19] , having a first weld bead and a second weld bead extending in the same direction as the first weld bead and partially overlapping the first weld bead, wherein the first weld bead has a protrusion, the second weld bead has a terminal portion and the second weld bead has a protrusion located on the first weld bead.

[22] : The semiconductor device according to

[19] , having a first weld bead and a second weld bead extending in the same direction as the first weld bead, wherein the first weld bead and the second weld bead are separated, and the first weld bead has a protrusion, a terminal portion of the first weld bead, a protrusion, and a terminal portion of the second weld bead.

[23] : The semiconductor device according to

[19] , having a first weld bead and a second weld bead extending in the opposite direction to the first weld bead and partially overlapping the first weld bead, wherein the first weld bead has a protrusion, the second weld bead has a terminal portion, and the second weld bead has a protrusion.

[0128] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and produces similar effects is included within the technical scope of this disclosure. [Explanation of Symbols]

[0129] 10... Semiconductor chip, 11... Metal pattern, 12... Ceramic substrate 13...Circuit board, 14...Inner lead, 14A...End of inner lead, 15…Lead frame, 16…Mold resin, 20...Pressing jig, 21, 21A, 21B...Pressing claws, 25...Irradiator, 30...Receiving jig, 40...Laser irradiation center point, 43, 43A, 43B... protruding parts (speech outlet areas), 45… Areas where laser irradiation is not possible. 50, 50A, 50B, 50C, 50D... weld marks, 51, 51A, 51B... Weld bead, 53... Starting position (starting point), 55, 55A, 55B...Terminal part, 100... Semiconductor equipment, 200... Intelligent Power Module (IPM), 300...Air conditioner, 310...Indoor unit, 320...Outdoor unit 311, 321... Fan motor, 322... Compressor. S, S1, S2... Direction of travel (direction), L... Laser beam, P1, P2... Laser irradiation distance.

Claims

1. A method for connecting inner leads, comprising laser welding an inner lead to a lead frame having an inner lead with a metal pattern on the surface of a circuit board on which a semiconductor chip is mounted, and an inner lead having a lower surface that contacts the metal pattern on the circuit board at its end, by irradiating the inner lead with laser light from the upper surface side, The upper surface of the metal pattern and the lower surface of the end of the inner lead are brought into contact. Using a pressing jig equipped with a plurality of pressing claws for pressing the end of the inner lead against the upper surface of the metal pattern, the end of the inner lead is pressed from above. A method for connecting an inner lead, characterized by irradiating the region between the plurality of pressing claws with the laser beam in the direction from one of the pressing claws to the other, thereby laser welding the metal pattern of the circuit board to the inner lead.

2. The method for connecting an inner lead according to claim 1, characterized in that the aforementioned irradiation is performed multiple times.

3. The method for connecting an inner lead according to claim 2, characterized in that, when the number of times is N times (where N ≥ 2), the laser irradiation area of ​​the Nth time traveling irradiation is superimposed on a part of the laser irradiation area of ​​the N-1 time traveling irradiation.

4. The method for connecting an inner lead according to claim 2, characterized in that, when the number of times is N times (where N ≥ 2), the laser irradiation area of ​​the N-1th time traveling irradiation and the laser irradiation area of ​​the Nth time traveling irradiation are separated in the direction of traveling irradiation.

5. The method for connecting an inner lead according to claim 1, characterized in that, following the aforementioned traveling irradiation, the laser beam is further irradiated from the other pressing claw toward the direction of the one pressing claw.

6. Using the pressing jig equipped with the two pressing claws, The starting position when the laser beam is projected from one of the pressing claws toward the other pressing claw is set to approximately the midpoint between the two pressing claws. The method for connecting an inner lead according to claim 5, characterized in that the starting position when the laser beam is irradiated from the other pressing claw toward the one pressing claw is substantially the same as the starting position when the laser beam is irradiated from the one pressing claw toward the other pressing claw.

7. The method for connecting an inner lead according to claim 1, characterized in that the aforementioned laser beam is irradiated using a galvanoscanning method.

8. The inner lead connection method according to claim 7, characterized in that a laser beam is irradiated from the pressing claw on the side closer to the laser irradiation center point in the galvanoscanning type laser irradiation, toward the other pressing claw on the side further from the laser irradiation center point.

9. The method for connecting an inner lead according to claim 7, characterized in that a plurality of the circuit boards are placed on a receiving jig, the positions of the laser beam irradiator and the receiving jig are adjusted so that the laser irradiation center point is located between the plurality of circuit boards, and the metal pattern and the inner lead are laser welded to each of the plurality of circuit boards.

10. The method for connecting inner leads according to claim 9, characterized in that for each of the plurality of circuit boards placed on the receiving jig, a lead frame is prepared which has an inner lead having a plurality of lead patterns arranged in a grid strip shape, the lead patterns of the lead frame are placed facing each other, and the positions of the laser beam irradiator and the receiving jig are adjusted so that the laser irradiation center point is located at the center between the lead patterns of the facing lead frames, and the metal pattern and the inner lead are laser welded to each of the plurality of circuit boards.

11. The method for connecting an inner lead according to claim 8, characterized in that the irradiation direction of the laser light is in a direction along the direction in which the inner lead extends from the outer lead side toward the end side.

12. A method for manufacturing a semiconductor device, characterized by including a step of joining the inner leads and the circuit board by the inner lead connection method described in any one of claims 1 to 11.

13. A method for manufacturing electrical equipment, characterized by manufacturing electrical equipment using a semiconductor device manufactured by the method for manufacturing a semiconductor device described in claim 12.

14. A semiconductor device characterized by being manufactured by the method for manufacturing a semiconductor device described in claim 12.

15. A method for connecting inner leads, comprising bringing the upper surface of the metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface into contact with the lower surface of an inner lead having an inner lead with a lower surface that contacts the metal pattern on the circuit board at its end, and laser welding by irradiating a laser beam from the upper surface side of the inner lead, A method for connecting an inner lead, characterized in that the aforementioned irradiation is performed in one direction on a single weld joint in multiple separate passes.

16. The method for connecting an inner lead according to claim 15, characterized in that, when the number of times is N times (where N ≥ 2), the laser irradiation area of ​​the Nth time traveling irradiation is superimposed on a part of the laser irradiation area of ​​the N-1 time traveling irradiation.

17. The method for connecting an inner lead according to claim 15, characterized in that, when the number of times is N times (where N ≥ 2), the laser irradiation area of ​​the N-1th time traveling irradiation and the laser irradiation area of ​​the Nth time traveling irradiation are separated in the direction of traveling irradiation.

18. A method for connecting inner leads, comprising bringing the upper surface of the metal pattern on a circuit board on which a semiconductor chip is mounted and which has a metal pattern on its surface into contact with the lower surface of an inner lead having an inner lead with a lower surface that contacts the metal pattern on the circuit board at its end, and laser welding by irradiating a laser beam from the upper surface side of the inner lead, The laser irradiation area on which the laser beam is irradiated is a linearly extending region, and the laser welding process includes a first laser welding process in which the laser beam is irradiated in one direction along the longitudinal direction of the laser irradiation area, and a second laser welding process in which the laser beam is irradiated in the other direction along the longitudinal direction so as to overlap a part of the first laser irradiation area of ​​the first laser welding process. A method for connecting an inner lead, characterized in that the traveling irradiation in the second laser welding step is terminated before reaching the starting position of the first laser welding step.

19. A semiconductor device comprising a circuit board having a metal pattern, a semiconductor chip mounted on the circuit board, and a lead frame having inner leads welded to the upper surface of the metal pattern on the circuit board, The weld marks in the weld area between the inner lead and the metal pattern include a terminal portion and a protrusion separated from the terminal portion, and have at least one weld bead that extends linearly when viewed from above. A semiconductor device characterized by having multiple instances of at least one of the terminal portion and the convex portion.

20. The semiconductor device according to claim 19, comprising a first weld bead and a second weld bead extending in the opposite direction to the first weld bead and partially overlapping the first weld bead, wherein the semiconductor device has a terminal portion of the first weld bead, a terminal portion of the second weld bead, and a protrusion of the second weld bead located on the first weld bead.

21. The semiconductor device according to claim 19, comprising a first weld bead and a second weld bead extending in the same direction as the first weld bead and partially overlapping the first weld bead, wherein the first weld bead has a protrusion, the second weld bead has a terminal portion, and the second weld bead has a protrusion located on the first weld bead.

22. The semiconductor device according to claim 19, comprising a first weld bead and a second weld bead extending in the same direction as the first weld bead, wherein the first weld bead and the second weld bead are separated, and the semiconductor device comprises a protrusion of the first weld bead, an end portion of the first weld bead, a protrusion of the second weld bead, and an end portion of the second weld bead.

23. The semiconductor device according to claim 19, comprising a first weld bead and a second weld bead extending in the opposite direction to the first weld bead and partially overlapping the first weld bead, wherein the first weld bead has a protrusion, the second weld bead has an end portion, and the second weld bead has a protrusion.

Images