Preliminary solder formation method and preliminary solder formation device

Abstract

To provide a preliminary solder formation method and a preliminary solder formation device which can satisfactorily form a preliminary solder on an aluminum electrode.SOLUTION: A preliminary solder formation method is a method for forming a preliminary solder 30 on an aluminum electrode 10 formed of aluminum. The preliminary solder formation method includes: an arrangement step of arranging a solder 20 on the aluminum electrode 10; and a joint step of melting and solidifying the solder 20 using the laser beam L, and thereby joining the solder 20 to the aluminum electrode 10. The joint step emits the laser beam L so that the energy amount of the laser beam L emitted to the aluminum electrode 10 is larger than the energy amount of the laser beam L emitted to the solder 20.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a preliminary solder forming method and a preliminary solder forming apparatus. [Background technology]

[0002] For example, Patent Document 1 describes a method of joining solder placed on an LSI chip to the LSI chip by irradiating the solder with laser light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-237963 Summary of the Invention [Problem to be solved by the invention]

[0004] When attempting to form preliminary solder on an aluminum electrode using the above-mentioned method, the wettability of the aluminum electrode with respect to the solder is poor, and therefore the solder may not be bonded satisfactorily.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a method and apparatus for forming preliminary solder that can satisfactorily form preliminary solder on an aluminum electrode. [Means for solving the problem]

[0006] The pre-solder forming method of the present invention is [1] "a pre-solder forming method for forming pre-solder on an aluminum electrode formed from aluminum, comprising: a placement step of placing solder on the aluminum electrode; and a joining step of joining the solder to the aluminum electrode by melting and solidifying the solder using laser light, wherein in the joining step, the laser light is irradiated so that the energy amount of the laser light irradiated to the aluminum electrode is greater than the energy amount of the laser light irradiated to the solder."

[0007] In the joining step of this preliminary solder forming method, a laser beam is irradiated so that the energy amount of the laser beam irradiated to the aluminum electrode is greater than the energy amount of the laser beam irradiated to the solder. This allows the aluminum electrode to be heated before the solder, and the aluminum electrode can be in a heated state at the time when the solder melts. As a result, the aluminum electrode can be made to be easily wetted by the solder at the joining portion with the solder, and the solder can be joined well to the aluminum electrode. Therefore, according to this preliminary solder forming method, the preliminary solder can be well formed on the aluminum electrode. Note that "the energy amount of the laser beam irradiated to the aluminum electrode is greater than the energy amount of the laser beam irradiated to the solder" includes the case where the energy amount of the laser beam irradiated to the solder is zero (i.e., the laser beam is not irradiated to the solder).

[0008] The pre-soldering method of the present invention may be [2] "the pre-soldering method according to [1], in which in the joining step, the aluminum electrode is irradiated with the entirety of the laser light." In this case, the aluminum electrode can be stably heated, and the yield can be improved.

[0009] The pre-soldering method of the present invention may be [3] "the pre-soldering method according to [1], in which in the joining step, a part of the laser light is irradiated onto the aluminum electrode, and the remaining part of the laser light is irradiated onto the solder." In this case, the aluminum electrode and the solder can be heated in a well-balanced manner, and the process can be shortened.

[0010] The pre-solder forming method of the present invention may be [4] "the pre-solder forming method according to any one of [1] to [3], wherein in the joining step, the laser light is irradiated so that the center of the laser light is located outside the solder." In this case, the laser light can be easily irradiated so that the energy amount of the laser light irradiated to the aluminum electrode is greater than the energy amount of the laser light irradiated to the solder.

[0011] The pre-solder forming method of the present invention may be [5] "the pre-solder forming method according to any one of [1] to [4], in which in the joining step, the laser light is irradiated so that the area of ​​the laser light irradiated to the aluminum electrode is larger than the area of ​​the laser light irradiated to the solder." In this case, the laser light can be easily irradiated so that the energy amount of the laser light irradiated to the aluminum electrode is larger than the energy amount of the laser light irradiated to the solder.

[0012] The preliminary solder forming method of the present invention may be [6] "the preliminary solder forming method according to any one of [1] to [5], in which in the joining step, the laser light is applied in a state in which a pressing member arranged on the opposite side of the aluminum electrode with respect to the solder is in contact with the solder." In this case, the solder can be joined to the aluminum electrode more satisfactorily.

[0013] The pre-solder forming method of the present invention may be [7] "the pre-solder forming method according to [6], in which the pressing member is transparent to the laser light, and in the joining step, the laser light is irradiated via the pressing member onto the surface of the aluminum electrode on which the solder is arranged." In this case, the laser light can be irradiated onto the area overlapping with the pressing member.

[0014] The pre-solder forming method of the present invention may be [8] "the pre-solder forming method according to any one of [1] to [7], in which in the joining step, the laser light is applied in a state in which the solder is surrounded by a surrounding member when viewed from the direction of irradiation of the laser light." In this case, the movement of the molten solder can be suppressed by the surrounding member, and the solder can be joined to the aluminum electrode more satisfactorily.

[0015] The pre-solder forming method of the present invention may be [9] "the pre-solder forming method according to [8], in which the surrounding member is made of epoxy glass or silicone." In this case, the thermal conductivity of the surrounding member can be reduced, and heat loss from the solder through the surrounding member can be suppressed. In addition, the heat resistance of the surrounding member can be increased, and damage to the surrounding member due to the temperature during processing can be suppressed.

[0016] The pre-solder forming method of the present invention may be

[10] "the pre-solder forming method according to [8] or [9], wherein the surrounding member is transparent to the laser light." In this case, since it is not necessary to irradiate the laser light while avoiding the surrounding member, irradiation of the laser light can be simplified.

[0017] The preliminary solder forming method of the present invention may be

[11] "the preliminary solder forming method according to any one of [1] to

[10] , in which in the joining step, a pressing member arranged on the opposite side of the aluminum electrode with respect to the solder is in contact with the solder, and the solder is surrounded by a surrounding member when viewed from the direction of irradiation of the laser light, and the pressing member and the surrounding member are integrally formed, and the laser light is applied." In this case, by using the pressing member and the surrounding member, the solder can be joined to the aluminum electrode more satisfactorily. Also, since the pressing member and the surrounding member are integrally formed, the number of members can be reduced, and the operation time can be shortened.

[0018] The preliminary solder forming method of the present invention may be

[12] "the preliminary solder forming method according to any one of [1] to

[11] , in which, in the joining step, the surface of the aluminum electrode on which the solder is arranged is irradiated with the laser light." In this case, the solder can be reliably joined to the aluminum electrode.

[0019] The pre-solder forming method of the present invention may be

[13] "the pre-solder forming method according to any one of [1] to

[11] , wherein in the joining step, the laser light is irradiated onto a surface of the aluminum electrode opposite to a surface on which the solder is arranged." In this case, since it is not necessary to irradiate the laser light while avoiding the solder, the irradiation of the laser light can be simplified.

[0020] The pre-solder forming method of the present invention may be

[14] "the pre-solder forming method according to any one of [1] to

[13] , in which, in the placing step, the solder containing flux is placed on the aluminum electrode." According to this pre-solder forming method, even solder containing flux can be satisfactorily bonded to the aluminum electrode.

[0021] The pre-solder forming apparatus of the present invention is

[15] "a pre-solder forming apparatus for forming pre-solder on an aluminum electrode formed of aluminum, comprising an irradiation unit that irradiates laser light and a control unit that controls the irradiation unit, the control unit causes the irradiation unit to irradiate the laser light so that the energy amount of the laser light irradiated to the aluminum electrode is greater than the energy amount of the laser light irradiated to the solder placed on the aluminum electrode, and the solder is melted and solidified, thereby joining the solder to the aluminum electrode." With this pre-solder forming apparatus, it is possible to satisfactorily join the solder to the aluminum electrode for the reasons described above. Effect of the Invention

[0022] According to the present invention, it is possible to provide a preliminary solder forming method and a preliminary solder forming apparatus that can satisfactorily join solder to an aluminum electrode. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a configuration diagram of a preliminary solder forming device. [Diagram 2] 1A to 1C are cross-sectional views for explaining a method for forming preliminary solder. [Diagram 3] 4 is a flowchart for explaining an operation of the pre-solder forming apparatus. [Figure 4] 13(a) and (b) are diagrams for explaining the irradiation position of the laser light. FIG. [Diagram 5] 11A and 11B are cross-sectional views for explaining a preliminary solder forming method of a comparative example. [Figure 6] 11A and 11B are cross-sectional views for explaining a preliminary solder forming method according to a first modified example. [Figure 7] FIG. 2 is a cross-sectional view showing a state in which solder is placed on the flux. [Figure 8] 13 is a cross-sectional view for explaining a pre-solder forming method according to a second modified example. FIG. [Figure 9]13A and 13B are cross-sectional views for explaining a preliminary solder forming method according to a third modified example. [Figure 10] 13 is a cross-sectional view for explaining a preliminary solder forming method according to a fourth modified example. FIG. [Figure 11] FIG. 13 is a configuration diagram of a preliminary solder forming apparatus according to a fifth modified example. [Figure 12] 13 is a flowchart illustrating the operation of a pre-solder forming apparatus according to a fifth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or corresponding elements are designated by the same reference numerals, and redundant description will be omitted.

[0025] As shown in Fig. 1, the preliminary solder forming apparatus 1 includes a frame 2, an irradiation head 3 (irradiation unit), a camera 4, and a control unit 5. The preliminary solder forming apparatus 1 is an apparatus for forming preliminary solder 30 (Fig. 2) on an aluminum electrode 10 formed from aluminum. The preliminary solder 30 is solder that is formed in advance on the aluminum electrode 10 before joining with a joining object. When soldering the aluminum electrode 10 with the joining object, for example, the preliminary solder 30 may be melted and solidified to join the aluminum electrode 10 with the joining object, or solder may be further added onto the preliminary solder 30 to join the aluminum electrode 10 with the joining object.

[0026] In the preliminary solder forming apparatus 1, laser light L is irradiated from an irradiation head 3 onto an aluminum electrode 10 arranged on a frame 2. The aluminum electrode 10 is formed, for example, in the shape of a rectangular plate. Solder 20 is arranged on the aluminum electrode 10, and the solder 20 is melted and solidified using the laser light L, whereby the solder 20 is joined to the aluminum electrode 10, and preliminary solder 30 is formed on the aluminum electrode 10. Details of this joining process will be described later.

[0027] The frame 2 has a base portion 2a and a cover portion 2b arranged on the base portion 2a. The frame 2 is formed in a box shape as a whole, and the base portion 2a constitutes the bottom wall portion. An aluminum electrode 10 to be processed is arranged on the base portion 2a. Solder 20 is arranged on the aluminum electrode 10. This solder 20 is a solder material before being joined to the aluminum electrode 10. The solder 20 may be, for example, a solder paste in which a spherical metal material is covered with a resin material.

[0028] The irradiation head 3 irradiates the aluminum electrode 10 with laser light L. The irradiation head 3 is attached to the cover 2b of the frame 2 so as to be movable along, for example, the XY plane. The XY plane is a plane perpendicular to the Z direction, which is the irradiation direction of the laser light L by the irradiation head 3. Note that it is only necessary that the irradiation head 3 and the base 2a are relatively movable along the XY plane, and the base 2a may be configured as a stage movable along the XY plane.

[0029] The camera 4 captures an image of the aluminum electrode 10 placed on the base portion 2a. The camera 4 is attached, for example, to the cover portion 2b of the frame 2. An example of an image P captured by the camera 4 is shown in FIG.

[0030] The control unit 5 is communicatively connected to each element of the preliminary solder forming apparatus 1, including the irradiation head 3 and the camera 4, and controls each element of the preliminary solder forming apparatus 1. The control unit 5 is configured by a computer including, for example, a processor such as a CPU, and storage media such as a RAM and a ROM.

[0031] A preliminary solder forming method performed by the preliminary solder forming apparatus 1 will be described. First, an aluminum electrode 10 is placed on the pedestal portion 2a, and solder 20 is placed on the aluminum electrode 10 (placement step). The placement step can be performed by, for example, a specified work machine. In the placement step, the solder 20 may be placed on the aluminum electrode 10 placed on the pedestal portion 2a, or the aluminum electrode 10 on which the solder 20 is placed may be placed on the pedestal portion 2a. The solder 20 is placed on the aluminum electrode 10 by, for example, a dispenser (dispenser 6 shown in FIG. 11, which will be described later).

[0032] Next, the solder 20 is melted and solidified using laser light L, thereby joining the solder 20 to the aluminum electrode 10 (joining step, FIG. 2). More specifically, the solder 20 is melted by irradiation with the laser light L, and then the irradiation of the laser light L is stopped, thereby cooling and solidifying the solder 20. In the joining step, the laser light L is irradiated from the irradiation head 3. More specifically, the control unit 5 controls the irradiation head 3 and causes the irradiation head 3 to irradiate the laser light L.

[0033] In the joining step, the laser light L is irradiated so that the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20. In this example, the laser light L is not irradiated to the solder 20, so the energy amount of the laser light L irradiated to the solder 20 is zero. In this example, as shown in FIG. 2, at the start of the joining step (in the state shown on the left side of FIG. 2), all of the laser light L is irradiated to the aluminum electrode 10. In addition, the laser light L is irradiated to the surface 10a of the aluminum electrode 10 on which the solder 20 is arranged.

[0034] Thus, in this example, the laser light L is not irradiated to the solder 20, and the entirety of the laser light L is irradiated to the aluminum electrode 10. As a result, the aluminum electrode 10 is heated first. Next, the solder 20 is heated by the heat from the aluminum electrode 10 and melts. The melted solder 20 moves to the heated portion of the aluminum electrode 10 (the portion irradiated with the laser light L) as shown on the right side of FIG. 2. The moved solder 20 solidifies in that portion and is bonded to the aluminum electrode 10. As a result, the preliminary solder 30 is formed on the aluminum electrode 10. In such a bonding process, the solder 20 is easily wetted to the heated portion of the aluminum electrode 10, so that the solder 20 can be reliably bonded to the aluminum electrode 10.

[0035] With reference to FIG. 3, the operation of the preliminary solder forming apparatus 1 in the joining step will be described. The control unit 5 controls each element of the preliminary solder forming apparatus 1 to perform each of the following operations. First, the camera 4 acquires an image of the aluminum electrode 10 (step S11). Next, the control unit 5 determines whether or not the entire area to be irradiated with the laser light L is located outside the solder 20 based on the image acquired by the camera 4 (for example, by image processing) (step S12). If it is determined that the entire area is located outside the solder 20 (YES in step S12), the control unit 5 causes the irradiation head 3 to start irradiating the laser light L (step S13). On the other hand, if it is determined that at least a part of the area is located inside the solder 20 (NO in step S12), the control unit 5 moves the irradiation head 3 (step S14). Thereafter, the control unit 5 executes the process of step S11 again. With the above process, irradiation of the laser light L is started in a state in which the entire laser light L is irradiated to the aluminum electrode 10.

[0036] Here, the irradiation position of the laser light L will be described with reference to FIG. 4. In the upper part of FIG. 4(a) and FIG. 4(b), a cross-sectional view is shown, and in the lower part, a plan view is shown. As shown in FIG. 4(a), in the above-mentioned example, the entire laser light L is irradiated to the aluminum electrode 10. In FIG. 4(a), the center C of the laser light L is located outside the solder 20 (solder 20 before melting) (solder 20 at the start of the joining process). The center C is the center of the irradiation area (irradiation spot) of the laser light L on the surface 10a of the aluminum electrode 10. Also, in FIG. 4(a), in a plan view (when viewed from the Z direction), the area of ​​the laser light L irradiated to the aluminum electrode 10 is larger than the area of ​​the laser light L irradiated to the solder 20. In this example, the laser light L is not irradiated to the solder 20, so the area of ​​the laser light L irradiated to the solder 20 is zero. "The center of the laser light is located outside the solder" means that the center of the laser light is located outside the area where the solder is arranged. For example, when the solder 20 is circular as in the example of Fig. 4, this means that the center C of the laser light L is located outside the outer periphery of the solder 20, and when the solder 20 is annular, this means that the center C of the laser light L is located outside the outer periphery or inside the inner periphery of the solder 20.

[0037] The laser light L may be irradiated as shown in Fig. 4(b). In Fig. 4(b), a part of the laser light L is irradiated to the aluminum electrode 10, and the remaining part of the laser light L is irradiated to the solder 20. In Fig. 4(b) as well, the center C of the laser light L is located outside the solder 20. Also in Fig. 4(b), the area of ​​the laser light L irradiated to the aluminum electrode 10 is larger than the area of ​​the laser light L irradiated to the solder 20 in a plan view.

[0038] 4(b), the center C of the laser light L may be located on the outer edge of the solder 20. In this case as well, the area of ​​the laser light L irradiated to the aluminum electrode 10 becomes larger than the area of ​​the laser light L irradiated to the solder 20 in a plan view.

[0039] In any of the above cases, the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20. For example, when the intensity distribution of the laser light L is uniform, these energy amounts are proportional to the irradiation area of ​​the laser light L. When the intensity distribution of the laser light L is not uniform, the energy amount is a value obtained by integrating the intensity distribution of the laser light L in the irradiation area of ​​the corresponding laser light L. The intensity distribution of the laser light L may be a Gaussian distribution or a top hat distribution (uniform distribution). Note that it is sufficient that the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20, and unlike the examples of Figures 4(a) and 4(b), the center C of the laser light L may be located inside the solder 20.

[0040] The advantages of the preliminary solder forming method of the embodiment will be described with reference to the comparative example of FIG. 5. In the preliminary solder forming method of the comparative example of FIG. 5, the entire laser light L is irradiated to the solder 20. In this case, the energy amount of the laser light L irradiated to the aluminum electrode 10 is zero, which is less than the energy amount of the laser light L irradiated to the solder 20. Therefore, the solder 20 is heated first, and melts before the aluminum electrode 10 is heated. As a result, the solder 20 is difficult to wet to the unheated aluminum electrode 10, so that as shown on the right side of FIG. 5, the solder 20 becomes spherical and moves on the aluminum electrode 10, and the solder 20 cannot be joined to the aluminum electrode 10 well. In addition, since the contact area between the solder 20 and the aluminum electrode 10 is small, it is difficult to heat the aluminum electrode 10 with heat from the solder 20, and this also makes it difficult to join the solder 20 well. The reason that the solder 20 becomes spherical as shown on the right side of FIG. 5 is that the free energy of the solder 20 is large.

[0041] One reason why the aluminum electrode 10 has poor wettability with the solder 20 is the influence of a passivation film that forms on the surface of the aluminum electrode 10. When aluminum is placed in the air, a passivation film made of aluminum oxide (Al2O3) forms on its surface. Due to the presence of this passivation film, solder does not easily wet the aluminum electrode.

[0042] In order to solve this problem, the solder may contain flux to promote soldering. The flux is added to the solder for the purpose of removing the passivation film formed on the surface of the aluminum electrode. However, even in this case, it takes time to remove the passivation film with the flux, and there is a risk that the solder will melt before the passivation film is removed, and the solder will become ball-shaped and move on the aluminum electrode.

[0043] In this regard, as described above, in the preliminary solder forming method of the embodiment, the aluminum electrode 10 is irradiated with laser light L, and the aluminum electrode 10 is heated (FIG. 2). Then, the heat from the aluminum electrode 10 heats and melts the solder 20. The melted solder 20 moves to the heated portion of the aluminum electrode 10 and solidifies. Since the solder 20 easily wets the heated portion of the aluminum electrode 10, the solder 20 can be reliably joined to the aluminum electrode 10. Furthermore, since the solder 20 moves (gathers) to the heated portion of the aluminum electrode 10, the solder 20 can be easily positioned. [Action and Effects]

[0044] In the preliminary solder forming method of the embodiment, the laser light L is irradiated so that the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20. This allows the aluminum electrode 10 to be heated before the solder 20, and the aluminum electrode 10 can be in a heated state at the time when the solder 20 melts. As a result, the aluminum electrode 10 can be made more wettable with the solder 20 at the joint with the solder 20, and the solder 20 can be joined to the aluminum electrode 10 in a good condition. Therefore, according to the preliminary solder forming method of the embodiment, the preliminary solder 30 can be formed on the aluminum electrode 10 in a good condition. Note that "the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20" includes a case where the energy amount of the laser light L irradiated to the solder 20 is zero (i.e., the laser light L is not irradiated to the solder 20).

[0045] In the bonding process, the aluminum electrode 10 is irradiated with the entire laser light L. This allows the aluminum electrode 10 to be stably heated and the yield to be improved. That is, compared to the case where the aluminum electrode 10 is irradiated with only a portion of the laser light L, for example, it is easier to adjust the irradiation position of the laser light L and the aluminum electrode 10 can be stably heated.

[0046] In the joining step, a part of the laser light L may be irradiated onto the aluminum electrode 10, and the remaining part of the laser light L may be irradiated onto the solder 20. In this case, the aluminum electrode 10 and the solder 20 can be heated in a well-balanced manner, and the process can be shortened.

[0047] In the joining step, the laser light L is irradiated so that the center of the laser light L is located outside the solder 20. This makes it possible to easily irradiate the laser light L so that the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20. The preliminary solder forming method of the embodiment is particularly effective when the intensity distribution of the laser light L is a Gaussian distribution in which the light intensity is high in the central portion, or a top hat distribution in which the light intensity is uniform.

[0048] In the joining step, the laser light L is irradiated so that the area of ​​the laser light L irradiated to the aluminum electrode 10 is larger than the area of ​​the laser light L irradiated to the solder 20. This makes it possible to easily irradiate the laser light L so that the energy amount of the laser light L irradiated to the aluminum electrode 10 is larger than the energy amount of the laser light L irradiated to the solder 20.

[0049] In the bonding step, the surface 10a of the aluminum electrode 10 on which the solder 20 is disposed is irradiated with laser light L. This makes it possible to bond the solder 20 to the aluminum electrode 10 reliably.

[0050] The preliminary solder forming apparatus 1 is an apparatus for forming preliminary solder 30 on an aluminum electrode 10 formed of aluminum. The preliminary solder forming apparatus 1 includes an irradiation head 3 (irradiation unit) that irradiates laser light L, and a control unit 5 that controls the irradiation head 3. The control unit 5 causes the irradiation head 3 to irradiate the laser light L so that the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20 arranged on the aluminum electrode 10, and melts and solidifies the solder 20, thereby joining the solder 20 to the aluminum electrode 10. The preliminary solder forming apparatus 1 makes it possible to satisfactorily join the solder to the aluminum electrode 10 for the reasons described above. [Variations]

[0051] As in the first modified example shown in FIG. 6, in the joining step, the laser light L may be irradiated in a state where a pressing member 40 arranged on the opposite side of the aluminum electrode 10 with respect to the solder 20 is in contact with the solder 20. The pressing member 40 is made of a material that is transparent to the laser light L. In this example, the pressing member 40 is formed in a plate shape from glass. In this example, the laser light L is irradiated onto the surface 10a of the aluminum electrode 10 through the pressing member 40 (by passing through the pressing member 40). In the first modified example as well, the entire laser light L is irradiated onto the aluminum electrode 10. When the laser light L is irradiated while the pressing member 40 is pressed against the solder 20, the solder 20 melts, and the movement of the solder 20 can be restricted by the pressing member 40.

[0052] The preliminary solder forming method of the first modified example can be suitably used when the solder 20 contains flux. As shown in Fig. 7, when the solder 20 contains flux 21, the solder 20 is placed on the flux 21, and there is a possibility that the solder 20 cannot be joined to the aluminum electrode 10 satisfactorily.

[0053] 6, in contrast, when pressing member 40 is used, heated solder 20 expands, and because pressing member 40 restricts the upward movement in the figure, a force is applied to solder 20 in the downward direction in the figure (toward the side of aluminum electrode 10). This force allows solder 20 to push aside flux 21 and come into contact with aluminum electrode 10, as shown in FIG. 6, and solder 20 can be satisfactorily joined to aluminum electrode 10.

[0054] According to the first modification, the preliminary solder 30 can be well formed on the aluminum electrode 10, as in the above embodiment. Moreover, the pressing member 40 arranged on the opposite side of the aluminum electrode 10 with respect to the solder 20 is in contact with the solder 20, and the laser light L is applied to the solder 20, so that the solder 20 can be better joined to the aluminum electrode 10. Moreover, the pressing member 40 is transparent to the laser light L, and in the joining step, the laser light L is applied to the surface 10a of the aluminum electrode 10 on which the solder 20 is arranged, via the pressing member 40, so that the laser light L can be applied to the area overlapping with the pressing member 40. Moreover, even if the solder 20 contains the flux 21, it can be well joined to the aluminum electrode 10. In the joining step of the first modification, as in the above embodiment, a part of the laser light L may be applied to the aluminum electrode 10, and the remaining part of the laser light L may be applied to the solder 20.

[0055] As in the second modified example shown in FIG. 8, in the joining step, the laser light L may be irradiated in a state where the solder 20 is surrounded by the surrounding member 50 in a plan view (when viewed from the direction of irradiation of the laser light L). The surrounding member 50 is formed of a material having a melting point higher than that of the solder 20 and having low bonding property with the solder 20. The surrounding member 50 is also formed of a material that is transparent to the laser light L. In this example, the surrounding member 50 is formed of epoxy glass or silicone. The surrounding member 50 has a pressing portion 51 arranged on the opposite side of the solder 20 to the aluminum electrode 10, and a side wall portion 52 that surrounds the solder 20 in a plan view. The pressing portion 51 and the side wall portion 52 are formed integrally with each other, for example.

[0056] As shown in FIG. 8, in this example, the laser light L is irradiated to the outside of the surrounding member 50, and in the second modified example, the entire laser light L is irradiated to the aluminum electrode 10. By irradiating the laser light L with the solder 20 surrounded by the surrounding member 50, the movement of the molten solder 20 can be suppressed, and the solder 20 can be reliably joined to the aluminum electrode 10 inside the surrounding member 50. Also, in the second modified example, as in the first modified example, the pressing portion 51 is pressed against the solder 20 and the laser light L is irradiated to melt the solder 20, thereby restricting the movement of the solder 20 in the Z direction. That is, the pressing portion 51 can be regarded as a pressing member that performs the same function as the pressing member 40 in the first modified example. In this case, the side wall portion 52 can be regarded as a surrounding member. In the joining process of the second modified example, the laser light L is irradiated with the pressing portion 51 in contact with the solder 20 and the solder 20 surrounded by the side wall portion 52. This allows the solder 20 to be joined well to the aluminum electrode 10. In addition, since the pressing portion 51 and the side wall portion 52 are integrally formed, the number of components can be reduced, and the operation time can be shortened. In the second modified example, the surrounding member 50 may have only the side wall portion 52 without the pressing portion 51. In the joining process of the second modified example, a part of the laser light L may be irradiated to the aluminum electrode 10, and the remaining part of the laser light L may be irradiated to the solder 20, as in the above embodiment. In the example of FIG. 8, the laser light L is irradiated to the aluminum electrode 10 on the outside of the side wall portion 52, but the laser light L may be irradiated to the aluminum electrode 10 on the inside of the side wall portion 52. In this case, the laser light L is irradiated to the aluminum electrode 10 through the pressing portion 51.

[0057] According to the second modified example, the preliminary solder 30 can be well formed on the aluminum electrode 10, as in the above embodiment. Moreover, since the laser light L is irradiated while the solder 20 is surrounded by the surrounding member 50 in a plan view, the movement of the molten solder 20 can be suppressed by the surrounding member 50, and the solder can be more well joined to the aluminum electrode 10. Moreover, since the surrounding member 50 is made of epoxy glass or silicone, the thermal conductivity of the surrounding member 50 can be reduced, and the escape of heat from the solder 20 through the surrounding member 50 can be suppressed. Moreover, the heat resistance of the surrounding member 50 can be increased, and the surrounding member 50 can be suppressed from being damaged (e.g., burnt) due to the temperature during processing. Moreover, since the surrounding member 50 is transparent to the laser light L, it is not necessary to irradiate the laser light L while avoiding the surrounding member 50, and the irradiation of the laser light L can be simplified.

[0058] As in the third modified example shown in FIG. 9, in the bonding step, the surface 10b of the aluminum electrode 10 opposite to the surface 10a may be irradiated with laser light L while the surface 10a of the aluminum electrode 10 is in contact with the solder paste layer 60, which is the base material of the solder 20. In the third modified example, the surface 10b is heated by irradiation with the laser light L, and the heat is transferred to the surface 10a, thereby melting a part of the solder paste layer 60 (solder 20). The molten solder paste layer 60 solidifies and bonds to the surface 10a of the aluminum electrode 10. In the third modified example, the molten part (solder 20) of the solder paste layer 60 is surrounded by the unmelted part of the solder paste layer 60, so that the movement of the molten solder 20 can be suppressed, and the solder 20 can be reliably bonded to the aluminum electrode 10. That is, the unmelted part of the solder paste layer 60 can also be regarded as an enclosing member that performs the same function as the enclosing member 50 of the second modified example.

[0059] As in the above embodiment, the third modified example also makes it possible to satisfactorily form the preliminary solder 30 on the aluminum electrode 10. Moreover, since the laser light L is irradiated to the surface 10b of the aluminum electrode 10 opposite to the surface 10a on which the solder 20 is arranged, it is not necessary to irradiate the laser light L while avoiding the solder 20, and thus the irradiation of the laser light L can be simplified.

[0060] 10, in the bonding step, laser light L may be irradiated to surface 10b of aluminum electrode 10 opposite surface 10a. In the fourth modification, surface 10b is heated by irradiation with laser light L, and the heat is transferred to surface 10a, melting solder 20. The molten solder 20 solidifies and bonds to surface 10a of aluminum electrode 10.

[0061] As in the above embodiment, the fourth modified example also makes it possible to satisfactorily form the preliminary solder 30 on the aluminum electrode 10. Moreover, since the laser light L is irradiated to the surface 10b of the aluminum electrode 10 opposite to the surface 10a on which the solder 20 is arranged, it is not necessary to irradiate the laser light L while avoiding the solder 20, and thus the irradiation of the laser light L can be simplified.

[0062] As in the fifth modified example shown in FIG. 11, the preliminary solder forming apparatus 1 may not include the camera 4. In this case, the control unit 5 controls the irradiation position of the laser light L by the irradiation head 3 by numerical control instead of image recognition. In this case, as shown in FIG. 12, first, the dispenser 6 places (applies) a predetermined amount of the solder 20 at a predetermined position on the aluminum electrode 10 (step S21). Then, the control unit 5 acquires position information of the solder 20 from the dispenser 6 (step S22). Then, the control unit 5 moves the irradiation head 3 to a position corresponding to the solder 20 (step S23). Then, the control unit 5 causes the irradiation head 3 to start irradiating the laser light L (step S24). Through the above process, for example, irradiation of the laser light L is started in a state in which the entire laser light L is irradiated to the aluminum electrode 10. According to the fifth modified example, the solder 20 can be joined well to the aluminum electrode 10, as in the above embodiment. In the joining step of the fifth modified example, a part of the laser light L may be irradiated onto the aluminum electrode 10, and the remaining part of the laser light L may be irradiated onto the solder 20, similarly to the above embodiment.

[0063] The present invention is not limited to the above-mentioned embodiment and modified examples. For example, the material and shape of each component are not limited to the above-mentioned material and shape, and various materials and shapes can be adopted. The shape of the irradiation area of ​​the laser light L is not limited to the circular shape shown in FIG. 5, and may be any shape. The shape of the irradiation area of ​​the laser light L may be a donut shape (annular shape). The shape of the aluminum electrode 10 is not limited to a plate shape, and may be any shape.

[0064] In the above embodiment, the laser light is irradiated so that the energy amount of the laser light L irradiated to the aluminum electrode 10 is greater than the energy amount of the laser light L irradiated to the solder 20. However, the laser light L may be irradiated so that the energy amount of the laser light L absorbed by the aluminum electrode 10 is greater than the energy amount of the laser light L absorbed by the solder 20. That is, the laser light L may be irradiated by further considering the absorptance of the laser light L of the aluminum electrode 10 and the solder 20. The absorptance of the solder 20 is higher than the absorptance of the aluminum electrode 10. The energy amount of the laser light L absorbed by the aluminum electrode 10 is the amount obtained by multiplying the energy amount of the laser light L irradiated to the aluminum electrode 10 by the absorptance of the laser light L of the aluminum electrode 10, and the energy amount of the laser light L absorbed and irradiated by the solder 20 is the amount obtained by multiplying the energy amount of the laser light L irradiated to the solder 20 by the absorptance of the laser light L of the solder 20. In this case as well, the solder 20 can be well joined to the aluminum electrode 10. [Explanation of symbols]

[0065] 1...pre-solder forming device, 3...irradiation head (irradiation unit), 5...control unit, 10...aluminum electrode, 10a, 10b...surface, 20...solder, 21...flux, 30...pre-solder, 40...pressing member, 50...surrounding member, 51...pressing unit (pressing member), 52...side wall portion (surrounding member), C...center, L...laser light.

Claims

1. A method for forming a pre-solder on an aluminum electrode made of aluminum, comprising the steps of: a step of disposing solder on the aluminum electrode; a joining step of joining the solder to the aluminum electrode by melting and solidifying the solder using a laser beam, In the joining step, the laser light is irradiated so that the amount of energy of the laser light irradiated to the aluminum electrode is greater than the amount of energy of the laser light irradiated to the solder.

2. 2. The method for forming preliminary solder according to claim 1, wherein in the joining step, the aluminum electrode is irradiated with the entire laser light.

3. 2. The method of claim 1, wherein in the joining step, a part of the laser beam is irradiated onto the aluminum electrode, and a remaining part of the laser beam is irradiated onto the solder.

4. 4. The method of claim 1, wherein in the joining step, the laser light is irradiated so that a center of the laser light is positioned outside the solder.

5. 4. The method for forming preliminary solder according to claim 1, wherein in the joining step, the laser light is irradiated so that an area of ​​the laser light irradiated to the aluminum electrode is larger than an area of ​​the laser light irradiated to the solder.

6. 3. The method according to claim 1, wherein in the joining step, the laser light is applied while a pressing member arranged on a side of the solder opposite to the aluminum electrode is in contact with the solder.

7. the pressing member is transparent to the laser light, 7. The method according to claim 6, wherein in the joining step, the laser light is irradiated via the pressing member onto the surface of the aluminum electrode on which the solder is disposed.

8. 3. The preliminary solder forming method according to claim 1, wherein in the joining step, the laser light is irradiated in a state in which the solder is surrounded by a surrounding member when viewed from a direction in which the laser light is irradiated.

9. 9. The method for forming preliminary solder according to claim 8, wherein the surrounding member is made of epoxy glass or silicone.

10. The method for forming pre-solder according to claim 8 , wherein the surrounding member is transparent to the laser light.

11. In the joining step, the laser light is irradiated in a state in which a pressing member disposed on the opposite side of the aluminum electrode with respect to the solder is in contact with the solder and the solder is surrounded by a surrounding member when viewed from the irradiation direction of the laser light, 3. The method for forming preliminary solder according to claim 1, wherein the pressing member and the surrounding member are integrally formed.

12. 3. The method of claim 1, wherein in the joining step, the surface of the aluminum electrode on which the solder is disposed is irradiated with the laser light.

13. 3. The method of claim 1, wherein in the joining step, the laser light is irradiated onto a surface of the aluminum electrode opposite to a surface on which the solder is disposed.

14. 3. The method for forming preliminary solder according to claim 1, wherein in the placing step, the solder containing flux is placed on the aluminum electrode.

15. A pre-solder forming apparatus for forming pre-solder on an aluminum electrode formed of aluminum, comprising: an irradiation unit that irradiates laser light; A control unit that controls the irradiation unit, The control unit causes the irradiation unit to irradiate the laser light so that the amount of energy of the laser light irradiated to the aluminum electrode is greater than the amount of energy of the laser light irradiated to the solder placed on the aluminum electrode, and the solder is joined to the aluminum electrode by melting and solidifying it.

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