JP2004058109A - Bonding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bonding method for bonding a wire-like member to a bonding surface with high accuracy without affecting other parts than the bonding surface of a workpiece by the melting heat. <P>SOLUTION: A conductive wire 16 is placed on a thin film electrode 14, and an end part 18 of the conductive wire 16 is protruded by a predetermined quantity from a side edge part 14a of the thin film electrode 14. The end part 18 of the conductive wire 16 is irradiated with laser beams 20, and when the temperature of the conductive wire 16 exceeds the conductor melting temperature of the conductive wire 16, the end part 18 is melted, and the molten end part 18 forms a spherical conductor by the surface tension. The spherical conductor is moved in a direction of an arrow toward an electronic component 10, and when it reaches the side edge part 14a, the thin film electrode 14 is melted by the heat of the spherical conductor. As a result, the side edge part 14a of the thin film electrode 14 is bonded to the conductive wire 16, and the spherical conductor is cooled and solidified to form a bonded part. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a joining method in which a linear member is melted and joined to a joining surface of a workpiece.
[0002]
[Prior art]
Conventionally, as a joining method for melting and joining a linear member to a joining surface of a workpiece, a heated heater is pressed against the linear member brought into contact with the joining surface, and the joining surface and the linear member As shown in FIG. 4, a laser beam spot 108, an arc or a torch is applied to a part 106 of the linear member 104 brought into contact with the joining surface 102 of the workpiece 100, as shown in FIG. There is a joining method in which the joining surface 102 and the linear member 104 are joined by projecting and applying heat of fusion to a part 106 of the linear member 104.
[0003]
[Problems to be solved by the invention]
However, in the joining method in which the heated heater is pressed, pressure is applied to the joint surface of the workpiece, and thus there is a risk of causing a change in surface shape such as a crack on the joint surface. Moreover, since the heater is easily consumed in this joining method, the heater needs to be frequently replaced, which may lead to an increase in cost required for joining the workpiece and the linear member.
[0004]
On the other hand, in the joining method using a laser beam, an arc, or a torch, for example, when joining a minute linear member 104, it is extremely difficult to reduce the laser beam spot 108 in accordance with the linear member 104. is there. Therefore, the bonding surface 102 may be melted more than necessary, and a change in surface shape such as a crack may occur. Further, if the positioning accuracy of the spot 108 projected on the linear member 104 is poor, a laser beam is projected onto an electronic element or the like provided on the bonding surface 102 in the vicinity of the linear member 104, and the electronic element or the like is projected. There is also a risk of degrading the function.
[0005]
The present invention has been made to solve such a problem, and joins a linear member to a joint surface of a workpiece with high accuracy without affecting the part other than the joint surface due to heat of fusion. It aims at providing the joining method which can be done.
[0006]
[Means for Solving the Problems]
In the joining method according to the present invention, in the joining method in which the linear member is melted and joined to the joining surface of the workpiece, a part of the linear member protrudes from the side edge portion of the joining surface. The linear member is brought into contact with the side edge portion, a heat of fusion is applied to a predetermined portion of the linear member protruding from the side edge portion, the predetermined portion is melted, and the molten predetermined portion is continued. The linear member is melted by heat applied to the predetermined portion and moved toward the side edge portion, and the linear member is joined to the side edge portion.
[0007]
In this case, when melting heat is applied to a predetermined portion of the linear member protruding from the side edge portion of the joint surface, the linear member in that portion is melted. The linear member in a molten state becomes spherical due to surface tension, and moves while enlarging while melting the continuous linear member, and is finally joined to the side edge portion. As a result, the linear member is joined to the joining surface of the workpiece.
[0008]
When the linear member is melted, the predetermined portion protruding from the side edge portion is melted, so that the heat of fusion is not directly projected onto the workpiece, and the surface shape changes such as cracks on the joint surface of the workpiece. The problem of occurrence can be avoided. Further, since it is only necessary to melt the linear member by applying melting heat to a predetermined portion of the linear member, the melting means does not require high positioning accuracy and spot shape accuracy, The linear member can be accurately bonded also to the bonding surface.
[0009]
It is desirable that the melting heat applied to a predetermined part of the linear member is applied by a melting means in a non-contact state selected from laser beam welding, arc welding, or gas welding. In this case, the frequency of maintenance in the joining apparatus such as replacement of the heater is reduced, and the cost required for joining the workpiece and the linear member can be reduced.
[0010]
If the work to which the linear member is welded is preheated to such an extent that problems such as cracks do not occur, or if the work is heated using a part of a laser beam having a predetermined spread, The linear members can be more reliably joined.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a bonding method according to an embodiment of the present invention (hereinafter referred to as a bonding method according to the first or second embodiment) will be described with reference to FIGS. 1 to 3C.
[0012]
As shown in FIG. 1, an electronic component 10 (work) to which the joining method according to the first embodiment is applied, for example, on a substrate 12 made of an electrically insulating material such as ceramics or a magnetic material such as ferrite, A thin film electrode 14 (bonding surface) made of a conductor such as Au or Ag is formed. In addition to the thin film electrode 14, a resistor, an inductor, a capacitor, a semiconductor element, and the like can be mounted on the electronic component 10.
[0013]
A conducting wire 16 that is a linear member is placed on the thin film electrode 14 of the electronic component 10. The end 18 of the conducting wire 16 is disposed so as to protrude from the side edge 14a of the thin film electrode 14 by a predetermined amount. In addition, as the conducting wire 16, a conductor whose surface is coated with an insulating film such as an oxide film can be used. For example, bonding wires such as aluminum wires and tungsten wires used for bonding semiconductor components can be used.
[0014]
Next, a method of joining the thin film electrode 14 and the conductive wire 16 will be described with reference to FIGS. 1 and 2A to 2C.
[0015]
First, a laser beam welding apparatus (not shown) is positioned with respect to the end portion 18 of the conducting wire 16 protruding a predetermined amount from the side edge portion 14 a of the thin film electrode 14. Next, the laser beam 20 is condensed by the lens 22 and irradiated to the end 18.
[0016]
In this case, since the electronic component 10 is not disposed on the optical axis of the laser beam 20, the electronic component 10 is not likely to be heated by the laser beam 20 beyond a predetermined level. Therefore, as shown in FIG. 2A, the size of the laser beam spot 24 of the laser beam 20 applied to the end 18 is such that the desired heat of fusion can be imparted to the end 18, as shown in FIG. It may be larger than the diameter, and it is sufficient that the laser beam 20 has a positioning accuracy within a range in which the end portion 18 is irradiated.
[0017]
When the end portion 18 is irradiated with the laser beam 20 and the temperature of the conducting wire 16 exceeds the melting temperature of a conductor such as Ag, the end portion 18 is melted. As shown in FIG. 2B, the end portion 18 is melted. The spherical conductor 26 is formed by the surface tension. The spherical conductor 26 has a temperature equal to or higher than the melting temperature of the conductive wire 16, and is enlarged while melting the continuous conductive wire 16, and moves in the direction of the arrow toward the electronic component 10. The irradiation of the end 18 of the laser beam 20 is stopped when the spherical conductor 26 is removed from the laser beam spot 24.
[0018]
When the spherical conductor 26 reaches the side edge 14 a of the thin film electrode 14, the thin film electrode 14 is melted by the heat of the spherical conductor 26. As a result, as shown in FIG. 2C, the side edge portion 14 a of the thin film electrode 14 and the conducting wire 16 are joined, and the spherical conductor 26 is cooled and solidified to form a joined portion 28.
[0019]
The amount of heat applied to the end 18 of the conductor 16 by the laser beam 20 and the irradiation position of the laser beam 20 on the end 18 are determined by the spherical conductor 26 formed by the melted end 18 causing the conductor 16 to be heated by its own heat. It is necessary to set so that the thin film electrode 14 can be reached by melting and moving.
[0020]
Furthermore, in the joining method according to the first embodiment described above, the end portion 18 of the conducting wire 16 is melted by using the laser beam 20, but the melting means of the end portion 18 of the conducting wire 16 is applied to the electronic component 10. Any melting means may be used as long as it does not give a predetermined or higher melting heat. For example, arc welding such as inert gas tungsten arc welding (TIG welding) or gas welding may be used. Moreover, in these melting means, the conducting wire 16 can be joined to the thin film electrode 14 without being in contact with the end portion 18 of the conducting wire 16. In the TIG welding, since an arc is projected from the tip of the probe onto the end 18 of the conducting wire 16, the probe is less consumed and the maintenance frequency of the welding means can be reduced. Therefore, the cost required for the joining can be reduced.
[0021]
In the first embodiment described above, the thin film electrode 14 is preheated to such an extent that a change in surface shape such as cracks does not occur, or a part of the laser beam 20 having a predetermined spread is used. The thin film electrode 14 may be heated. By doing so, the conducting wire 16 can be more reliably joined to the thin film electrode 14.
[0022]
Next, the joining method according to the second embodiment is shown in FIGS. 3A to 3C.
[0023]
As shown in FIGS. 3A to 3C, this joining method is applied to joining electrodes in an inductor 32 configured by winding a conducting wire 16 around a ferrite core 30.
[0024]
The ferrite core 30 has first and second electrode portions 34 and 36 at both ends. The first and second electrode portions 34 and 36 have corner portions 38 and 40, and a thin film made of Au, Ag or the like is formed on the surface. And the inductor 32 is comprised by joining the conducting wire 16 wound by the ferrite core 30, and the 1st and 2nd electrode parts 34 and 36. As shown in FIG.
[0025]
Next, a method for joining the first and second electrode portions 34 and 36 and the conductive wire 16 will be described.
[0026]
First, as shown in FIG. 3A, the laser beam 20 is irradiated to the conducting wire 16 spaced apart from the corner portions 38 and 40 by a predetermined distance in a state where a part of the conducting wire 16 is in contact with the corner portions 38 and 40. . The conducting wire 16 irradiated with the laser beam 20 is cut by melting, and as shown in FIG. 3B, the first and second spherical conductors 42 and 44 are formed by melting.
[0027]
Next, the first and second spherical conductors 42 and 44 move toward the corner portions 38 and 40 of the first and second electrode portions 34 and 36 while melting the conducting wire 16 by the applied heat of fusion. .
[0028]
As shown in FIG. 3C, when the first and second spherical conductors 42 and 44 reach the corner portions 38 and 40, they are joined to the first and second electrode portions 34 and 36. Next, the first and second spherical conductors 42 and 44 are cooled and solidified, whereby the first and second joint portions 46 and 48 are formed.
[0029]
As described above, in the second embodiment, the cutting operation of the conducting wire 16 and the joining operation of the conducting wire 16 to the first and second electrode portions 34 and 36 can be performed simultaneously.
[0030]
In the second embodiment described above, the first and second electrode portions 34 and 36 are preheated to such an extent that changes in the surface shape such as cracks do not occur, or have a predetermined spread. The first and second electrode portions 34 and 36 may be heated using a part of the beam 20. By doing so, the conducting wire 16 can be more reliably bonded to the first and second electrode portions 34 and 36.
[0031]
In addition, the joining method according to the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted without departing from the gist of the present invention.
[0032]
【The invention's effect】
As described above, according to the joining method according to the present invention, a part of the linear member protruding from the joining surface of the workpiece is melted, and the melting heat of the part of the linear member is used to In order to join the joining surface and the linear member, excessive melting heat is not applied to the joining surface, and it is possible to avoid the occurrence of a change in surface shape such as a crack due to unnecessary heat on the workpiece. Can do.
[0033]
In addition, since high-precision positioning is not required when applying heat of fusion to the linear member, for example, a joining operation between minute components can be easily and highly accurately performed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an electronic component to which a bonding method according to a first embodiment is applied.
FIG. 2A to FIG. 2C are explanatory diagrams of a bonding method according to the first embodiment.
FIG. 3A to FIG. 3C are explanatory diagrams of a joining method according to a second embodiment.
FIG. 4 is an explanatory diagram of a joining method according to a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Electronic component 12 ... Board | substrate 14 ... Thin film electrode 14a ... Side edge part 16 ... Conductor 18 ... End part 20 ... Laser beam 22 ... Lens 24 ... Laser beam spot 26, 42, 44 ... Spherical conductor 28, 46, 48 ... Joining Part 30 ... Ferrite core 32 ... Inductor 34, 36 ... Electrode part 38, 40 ... Corner part

Claims (2)

In the joining method of melting and joining the linear member to the joining surface of the workpiece,
In a state where a part of the linear member protrudes from the side edge of the joint surface, the linear member is brought into contact with the side edge,
Applying a heat of fusion to a predetermined portion of the linear member protruding from the side edge portion to melt the predetermined portion;
The linear member continuous to the melted predetermined portion is moved toward the side edge portion by melting by heat applied to the predetermined portion,
The joining method characterized by joining the said linear member to the said side edge part. The joining method according to claim 1,
The joining method, wherein the heat of fusion applied to a predetermined part of the linear member is applied by a melting means in a non-contact state selected from laser beam welding, arc welding or gas welding.

Images