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EP-4741088-A1 - PRELIMINARY SOLDER FORMING METHOD AND PRELIMINARY SOLDER FORMING DEVICE

EP4741088A1EP 4741088 A1EP4741088 A1EP 4741088A1EP-4741088-A1

Abstract

A pre-solder formation method is a method for forming pre-solder on an aluminum electrode formed of aluminum. The pre-solder formation method includes 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 a laser beam. In the joining step, the laser beam is irradiated so that an amount of energy of the laser beam irradiated to the aluminum electrode is larger than an amount of energy of the laser beam irradiated to the solder.

Inventors

  • MATSUMOTO, SATOSHI

Assignees

  • Hamamatsu Photonics K.K.

Dates

Publication Date
20260513
Application Date
20240605

Claims (15)

  1. A pre-solder formation method for forming pre-solder on an aluminum electrode formed of aluminum, the pre-solder formation method 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 a laser beam, wherein in the joining step, the laser beam is irradiated so that an amount of energy of the laser beam irradiated to the aluminum electrode is larger than an amount of energy of the laser beam irradiated to the solder.
  2. The pre-solder formation method according to claim 1, wherein in the joining step, all of the laser beam is irradiated to the aluminum electrode.
  3. The pre-solder formation method according to claim 1, wherein in the joining step, a part of the laser beam is irradiated to the aluminum electrode, and a remaining part of the laser beam is irradiated to the solder.
  4. The pre-solder formation method according to claim 1 or 3, wherein in the joining step, the laser beam is irradiated so that a center of the laser beam is located outside the solder.
  5. The pre-solder formation method according to claim 1 or 3, wherein in the joining step, the laser beam is irradiated so that an area of the laser beam irradiated to the aluminum electrode is larger than an area of the laser beam irradiated to the solder.
  6. The pre-solder formation method according to claim 1 or 2, wherein in the joining step, the laser beam is irradiated in a state where a pressing member disposed on a side opposite to the aluminum electrode with respect to the solder is in contact with the solder.
  7. The pre-solder formation method according to claim 6, wherein the pressing member has transparency with respect to the laser beam, and in the joining step, the laser beam is irradiated to a surface of the aluminum electrode on which the solder is disposed, through the pressing member.
  8. The pre-solder formation method according to claim 1 or 2, wherein in the joining step, the laser beam is irradiated in a state where the solder is surrounded by a surrounding member when viewed from an irradiation direction of the laser beam.
  9. The pre-solder formation method according to claim 8, wherein the surrounding member is formed of epoxy glass or silicone.
  10. The pre-solder formation method according to claim 8, wherein the surrounding member has transparency with respect to the laser beam.
  11. The pre-solder formation method according to claim 1 or 2, wherein in the joining step, the laser beam is irradiated in a state where a pressing member disposed on a side opposite to 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 an irradiation direction of the laser beam, and the pressing member and the surrounding member are integrally formed.
  12. The pre-solder formation method according to claim 1 or 2, wherein in the joining step, the laser beam is irradiated to a surface of the aluminum electrode on which the solder is disposed.
  13. The pre-solder formation method according to claim 1 or 2, wherein in the joining step, the laser beam is irradiated to a surface of the aluminum electrode on a side opposite to a surface on which the solder is disposed.
  14. The pre-solder formation method according to claim 1 or 2, wherein in the placement step, the solder containing flux is placed on the aluminum electrode.
  15. A pre-solder formation apparatus for forming pre-solder on an aluminum electrode formed of aluminum, the pre-solder formation apparatus comprising: an irradiation unit that irradiates a laser beam; and a control unit that controls the irradiation unit, wherein the control unit causes the irradiation unit to irradiate the laser beam so that an amount of energy of the laser beam irradiated to the aluminum electrode is larger than an amount of energy of the laser beam irradiated to solder disposed on the aluminum electrode, thereby joining the solder to the aluminum electrode by melting and solidifying the solder.

Description

Technical Field One aspect of the present disclosure relates to a pre-solder formation method and a pre-solder formation apparatus. Background Art For example, Patent Literature 1 describes a method of joining solder to an LSI chip by irradiating the solder disposed on the LSI chip with a laser beam. Citation List Patent Literature [Patent Literature 1] Japanese Unexamined Patent Publication No. H9-237963 Summary of Invention Technical Problem When attempting to form pre-solder on an aluminum electrode using the method as described above, the solder may not be satisfactorily joined because the wettability of the aluminum electrode with respect to the solder is poor. Accordingly, an object of one aspect of the present disclosure is to provide a pre-solder formation method and a pre-solder formation apparatus capable of satisfactorily forming pre-solder on an aluminum electrode. Solution to Problem A pre-solder formation method according to one aspect of the present disclosure is [1] "a pre-solder formation method for forming pre-solder on an aluminum electrode formed of aluminum, the pre-solder formation method including: 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 a laser beam, wherein in the joining step, the laser beam is irradiated so that an amount of energy of the laser beam irradiated to the aluminum electrode is larger than an amount of energy of the laser beam irradiated to the solder." In the joining step of this pre-solder formation method, the laser beam is irradiated so that the amount of energy of the laser beam irradiated to the aluminum electrode is larger than the amount of energy of the laser beam irradiated to the solder. Accordingly, the aluminum electrode can 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 wettability of the aluminum electrode with respect to the solder can be improved at the joining location with the solder, and the solder can be satisfactorily joined to the aluminum electrode. Therefore, with this pre-solder formation method, pre-solder can be satisfactorily formed on the aluminum electrode. Note that "the amount of energy of the laser beam irradiated to the aluminum electrode is larger than the amount of energy of the laser beam irradiated to the solder" includes a case where the amount of energy of the laser beam irradiated to the solder is zero (that is, the laser beam is not irradiated to the solder). The pre-solder formation method according to one aspect of the present disclosure may be [2] "the pre-solder formation method according to [1], wherein in the joining step, all of the laser beam is irradiated to the aluminum electrode." In this case, the aluminum electrode can be stably heated, and the yield can be improved. The pre-solder formation method according to one aspect of the present disclosure may be [3] "the pre-solder formation method according to [1], wherein in the joining step, a part of the laser beam is irradiated to the aluminum electrode, and a remaining part of the laser beam is irradiated to 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. The pre-solder formation method according to one aspect of the present disclosure may be [4] "the pre-solder formation method according to any one of [1] to [3], wherein in the joining step, the laser beam is irradiated so that a center of the laser beam is located outside the solder." In this case, the laser beam can be easily irradiated so that the amount of energy of the laser beam irradiated to the aluminum electrode is larger than the amount of energy of the laser beam irradiated to the solder. The pre-solder formation method according to one aspect of the present disclosure may be [5] "the pre-solder formation method according to any one of [1] to [4], wherein in the joining step, the laser beam is irradiated so that an area of the laser beam irradiated to the aluminum electrode is larger than an area of the laser beam irradiated to the solder." In this case, the laser beam can be easily irradiated so that the amount of energy of the laser beam irradiated to the aluminum electrode is larger than the amount of energy of the laser beam irradiated to the solder. The pre-solder formation method according to one aspect of the present disclosure may be [6] "the pre-solder formation method according to any one of [1] to [5], wherein in the joining step, the laser beam is irradiated in a state where a pressing member disposed on a side opposite to 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. The pre-solder formation method according to one aspect of the present disclosure may be [7] "the pre-