Method of soldering wiring members by laser beam irradiation

Abstract

Wiring members such as bus bars for electrically connecting electronic components are contained in a casing composed of a substrate and a cover for closing an opening of the substrate. A laser beam is irradiated on and around solder held in one of the wiring members through a laser-transparent portion formed in the cover of the casing. The solder is melted by energy of the laser beam, and the wiring members are electrically connected by the molten solder. The electronic components and wiring members may be encapsulated in the casing before or after the laser beam is irradiated. Since the laser beam is irradiated from outside the casing after the electronic components and wiring members are contained in the casing, they can be positioned in the casing with greater freedom.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a first bus bar and a second bus bar to be connected by laser beam irradiation, as a first embodiment of the present invention, showing an instant a laser beam is irradiated;

FIG. 2 is a cross-sectional view showing the same bus bars as in FIG. 1, showing a state after soldering by laser beam radiation is completed;

FIG. 3 (a) and (b) show an example of a shape of the first and the second bus bars in a plan view;

FIG. 4 is a cross-sectional view showing the bus bars on which a laser-absorbing film is formed;

FIG. 5 is a cross-sectional view showing a modified form of a cover through which the laser beam is irradiated;

FIG. 6 is a cross-sectional view showing another modified form of a cover through which the laser beam is irradiated;

FIG. 7 is a cross-sectional view showing bus bars to be connected and a cover having laser windows through which a laser beam is irradiated;

FIG. 8 is a cross-sectional view showing a modified form of the cover having a single laser window through which the laser beam is irradiated on the bus bars;

FIG. 9 is across-sectional view showing another modified form of the cover having a convex lens through which the laser beam is irradiated;

FIG. 10 is a cross-sectional view showing a modified form of the cover having a cylindrical wall through which the laser beam is irradiated on the bus bars;

FIG. 11 is a cross-sectional view showing the cover having the cylindrical wall, an opening of which is closed with a cap;

FIG. 12 is a cross-sectional view showing a cover similar to that shown in FIG. 11, an opening of which is closed with a laser-transparent portion;

FIG. 13 is a cross-sectional view showing a cover on which an electronic component is mounted and a substrate on which a laser beam is irradiated, as a second embodiment of the present invention, showing an instant the laser beam is irradiated;

FIG. 14 is a plan view partially showing the substrate shown in FIG. 13, on which a solder bump is formed;

FIG. 15 is a cross-sectional view showing the same view as shown in FIG. 13, showing a state after a laser beam irradiating process is completed; and

FIG. 16 is a plan view showing the same view as shown in FIG. 14, the solder being spread around a terminal after the laser beam irradiation.

Claims

1. A method of soldering wiring members, comprising: preparing a first elongated wiring member having a solder-holding hole passing through an entire thickness of the first wiring member;overlapping the first elongated wiring member on a second elongated wiring member;disposing holder in the solder-holding hole; andirradiating a laser beam on the first wiring member in a vicinity of the solder-holding hole to melt the solder and to connect the first wiring member to the second wiring member.

2. The method of soldering wiring members as in claim 1, wherein: the solder-holding hole is closed by a surface of the second wiring member at a side opposite to a direction from which the laser beam is irradiated.

3. The method of soldering wiring members as in claim 1, wherein: a solder fillet is formed around a corner of the solder-holding hole on a surface of the second wiring member where the second wiring member contacts the first wiring member.

4. The method of soldering wiring members as in claim 1, wherein: each of the first and the second wiring members includes a narrowed portion that alleviates heat transfer from a laser-irradiating region to a main body of the wiring members.

5. The method of soldering wiring members as in claim 1, wherein: a laser-irradiating region of the wiring members, on which the laser beam is irradiated, has a higher laser-absorbing ability than other regions of the wiring members.

6. The method of soldering wiring members as in claim 5, wherein: the laser-irradiating region is covered with a laser-absorbing film.

7. The method of soldering wiring members as in claim 5, wherein: The laser-irradiating region has a rough surface.

8. The method of soldering wiring members as in claim 1, wherein: the wiring members are substantially encapsulated in a casing having a laser-transparent portion, and the laser beam is irradiated from an outside of the casing through the laser-transparent portion.

9. The method of soldering wiring members as in claim 8, wherein: the casing is composed of a cover having the laser-transparent portion and a substrate; andthe first wiring member is connected to the substrate and the second wiring member is connected to the cover.

10. The method of soldering wiring members as in claim 9, wherein: the wiring members are encapsulated in the casing after the laser beam is irradiated.

11. The method of soldering wiring members as in claim 9, wherein: the wiring members are encapsulated in the casing before the laser beam is irradiated.

12. The method of soldering wiring members as in claim 8, wherein: the laser-transparent portion is made of a thin laser-transparent resin.

13. The method of soldering wiring members as in claim 8, wherein: the laser-transparent portion is an open window through which the laser beam is irradiated.

14. The method of soldering wiring members as in claim 12, wherein: the laser-transparent portion is a convex lens having an area larger than a laser-irradiating region on the wiring members.

15. The method of soldering wiring members as in claim 12, wherein: the laser-transparent portion is thinner than other portions of the casing.

16. The method of soldering wiring members as in claim 15, wherein: the laser-transparent portion is reinforced by projected beams.

17. The method of soldering wiring members as in claim 8, wherein: the casing includes at least either one of a laser-transparent portion or an open window for optically inspecting a state of the molten solder after the laser beam irradiation is completed.

18. The method of soldering wiring members as in claim 17, wherein: the open window for inspection is closed at the same time as the wiring members are encapsulated in the casing.

19. The method of soldering wiring members as in claim 17, wherein: the open window for inspection is also used as a ventilation window for preventing water condensation in the casing.

20. The method of soldering wiring members as in claim 8, wherein: the casing includes an exhaust hole for exhausting gas generated by irradiating the laser beam.

21. The method of soldering wiring members as in claim 20, wherein: the exhaust hole is also used as an inspection hole for optically inspecting a state of molten solder.

22. The method of soldering wiring members as in claim 20, wherein: the exhaust hole is also used as a ventilation hole for preventing water condensation in the casing.

23. The method of soldering wiring members as in claim 8, wherein: the casing includes a cylindrical wall for preventing gas generated by irradiation of the laser beam from dispersing in the casing, the cylindrical wall extending from the laser-transparent portion to a vicinity of a laser-irradiating region on the wiring members.

24. The method of soldering wiring members as in claim 23, wherein: the cylindrical wall extending from the laser-transparent portion of the casing reaches and contacts the laser-irradiating region on the wiring members.

25. A method of soldering wiring members, comprising: preparing a first wiring member having a first contacting surface and a second wiring member having a second contacting surface, the first wiring member having a solder-holding hole passing through an entire thickness of the first wiring member;overlapping the first wiring member on a second wiring member so that the first contacting surface contacts the second contacting surface;disposing solder in the solder-holding hole;containing the wiring members in a casing that is able to encapsulate the wiring members therein, the casing having a laser-transparent portion; andirradiating a laser beam on a laser-irradiating region on the wiring members so that the solder disposed in the solder-holding hole is melted and the first contacting surface is connected to the second contacting surface by the molten solder.

26. The method of soldering wiring members as in claim 25, wherein: the casing is composed of a cover having the laser-transparent portion and a substrate; andthe first wiring member is connected to the substrate and the second wiring member is connected to the cover.

27. The method of soldering wiring members as in claim 26, wherein: the wiring members are encapsulated in the casing after the laser beam is irradiated.

28. The method of soldering wiring members as in claim 26, wherein: the wiring members are encapsulated in the casing before the laser beam is irradiated.

29. The method of soldering wiring members as in claim 25, wherein: the laser-transparent portion is made of a thin laser-transparent resin.

30. The method of soldering wiring members as in claim 25, wherein: the laser-transparent portion is an open window through which the laser beam is irradiated.

31. The method of soldering wiring members as in claim 29, wherein: the laser-transparent portion is a convex lens having an area larger than a laser-irradiating region on the wiring members.

32. The method of soldering wiring members as in claim 25, wherein: the laser-transparent portion is thinner than other portions of the casing.

33. The method of soldering wiring members as in claim 29, wherein: the laser-transparent portion is reinforced by projected beams.

34. The method of soldering wiring members as in claim 25, wherein: the casing includes at least either one of a laser-transparent portion or an open window for optically inspecting a state of the molten solder after the laser beam irradiation is completed.

35. The method of soldering wiring members as in claim 34, wherein: the open window for inspection is closed at the same time as the wiring members are encapsulated in the casing.

36. The method of soldering wiring members as in claim 34, wherein: the open window for inspection is also used as a ventilation window for preventing water condensation in the closed casing.

37. The method of soldering wiring members as in claim 25, wherein: the casing includes an exhaust hole for exhausting gas generated by irradiating the laser beam.

38. The method of soldering wiring members as in claim 37, wherein: the exhaust hole is also used as an inspection hole for optically inspecting a state of molten solder.

39. The method of soldering wiring members as in claim 37, wherein: the exhaust hole is also used as a ventilation hole for preventing water condensation in the closed casing.

40. The method of soldering wiring members as in claim 25, wherein: the casing includes a cylindrical wall for preventing gas generated by irradiation of the laser beam from dispersing in the casing, the cylindrical wall extending from the laser-transparent portion to a vicinity of a laser-irradiating region on the wiring members.

41. The method of soldering wiring members as in claim 40, wherein: the cylindrical wall extending from the laser-transparent portion of the casing reaches and contacts the laser-irradiating region on the wiring members.

42. The method of soldering wiring members as in claim 1, wherein: the first wiring member and the second wiring member are bus bars.

43. The method of soldering wiring members as in claim 25, wherein: the first wiring member and the second wiring member are bus bars.

44. A method of soldering wiring members, comprising: preparing a first wiring member having a solder-holding portion and a through-hole formed in a vicinity of the solder-holding portion;disposing solid solder on the solder-holding portion;inserting a terminal wire, forming a second wiring member, of an electronic component into the through-hole; andirradiating a laser beam on the solid solder and its vicinity so that the solid solder is melted and flows into the through-hole to thereby connect the second wiring member to the first wiring member by soldering.