JP5441813B2 - Joining method and joining apparatus - Google Patents

Description

  The present invention relates to a joining method, a joining apparatus, and a joined body for joining a first member and a second member by laser light irradiation.

  Conventionally, various techniques relating to laser bonding between a bonding target body such as a lead and an electrode pad have been proposed. As one of them, the surface of the member to be bonded is irradiated with laser light through an optical waveguide made of a solid transparent member, and the object to be bonded is directly heated by a laser to generate heat and pressurize the electrode pad and the object to be bonded. A method of joining has been proposed.

Hereinafter, a conventional bonding method will be described with reference to FIG.
FIG. 9 is a schematic cross-sectional view for explaining a conventional joining method and joining apparatus.
For example, as shown in FIG. 9, a laser beam is introduced from an upper end surface 117 of a transparent bonding tool 115 attached to an ultrasonic horn 116, and a plate-like lead 103 is moved by a laser beam on a pressing surface 118 that is also a laser exit. In addition to assisting in heating, the electrode pad 105 and the lead 103 can be efficiently bonded by the frictional heat generated by the ultrasonic waves input from the ultrasonic horn 116 to improve the bonding quality (for example, see Patent Document 1).

JP-A-5-259220

However, the conventional laser-assisted joining method using an ultrasonic horn has the following problems.
First, the member to be joined is usually a high reflector of a laser such as a copper plate or a gold-plated plate, and since these materials are hardly heated because the laser is almost reflected on the surface, the joining quality by heat does not improve. Therefore, if you try to raise the temperature of the parts to be joined by strengthening the laser light, a lot of reflected laser light will scatter around, causing damage to the surrounding heat-sensitive resin package, etc., or returning the laser to the laser oscillator and returning The laser oscillator may be damaged by light.

  Moreover, since not only a laser but also an expensive and large ultrasonic horn is necessary, not only the apparatus becomes complicated, but also the shape of the pressurizing part may change due to friction, resulting in a problem that the bonding quality is not stable. It was.

  In view of the above problems, an object of the present invention is to bond various bonding materials such as gold plating and copper having high laser reflectivity with high speed, high quality and high stability with a simple configuration.

  In order to achieve the above object, a bonding apparatus according to the present invention absorbs a part of laser light, transmits the remainder of the laser light and irradiates the first member, the first member, and the first member. A holding table on which two members are placed, and the laser beam is transmitted through the pressing tool in a state where the first member is sandwiched between the pressing tool and the second member. While irradiating one member and pressurizing the first member with the pressurizing tool, the first member was heated, pressed and crushed to enlarge the contact area between the first member and the second member. The first member and the second member are heat diffusion bonded in a state.

Moreover, it is preferable to coat a material having a lower thermal conductivity than the holding table in advance on the pressing surface of the pressing tool or the surface of the holding table.
Furthermore, the bonding method of the present invention includes a step of placing the second member on the holding table, placing the first member on the second member, absorbing a part of the laser beam, A step of sandwiching the first member between a pressure tool that transmits the remainder and the second member; and irradiating the first member with the laser light through the pressure tool; and Pressurizing the first member, and crushing the first member with heat and pressure of the pressurizing tool heated by absorbing a part of the laser beam, and pressing the first member and the first member The two members are heat diffusion bonded.

Moreover, it is preferable that the absorption rate of the said laser beam of the said pressurization tool is 10 to 40%.
The first member is a wire coated with a resin, and the wire and the second member can be joined after the resin is thermally decomposed by the heating.

Moreover, it is preferable that the pressing surface or the holding table surface of the pressing tool is coated with a material having a lower thermal conductivity than the holding table or the resin.
Further, it is preferable that the laser beam irradiation is performed so as to gradually increase the power of the laser beam.
Moreover, it is preferable to heat the back surface with respect to the surface which contacts the said 1st member of the said 2nd member before the said pressurization.

Moreover, it is preferable to supply an inert gas around the heating part of the first member during the irradiation of the laser beam.
Alternatively, a material having a lower melting point than the first member may be used as the second member, only the second member is melted by the heating, and the first member may be embedded in the second member and joined.

The second member may be tin or a tin alloy, and the first member may be a wire.
Further, when the first member is placed, the first member is placed on the second member via a solder having a lower melting point than the first member, and only the solder is melted by the heating. The first member may be embedded in the solder and bonded.

Further, in the heating, return light of the laser beam generated at the interface between the first member and the pressing tool may be used.
Furthermore, the joined body of the present invention is a joined body joined by the joining method, wherein the wire as the first member and the metal plate as the second member are joined, and the wire and the metal plate are joined together. The surface roughness of the wire at the bonding interface is rougher than the surface roughness of the pressing surface of the wire.

  Moreover, it is a joined body joined by the joining method, wherein the wire which is the first member and the second member are joined, and a part of the surface of the wire embedded in the second member is the second. You may expose from a member.

  Using a pressing tool heated by absorption of laser light, laser irradiation is performed while crushing one member, and by joining the two members, it is possible to perform thermal diffusion bonding with the bonding area expanded Therefore, it is possible to bond various bonding materials such as gold plating and copper having high laser reflectivity with high speed, high quality and high stability with a simple configuration.

Process sectional drawing which shows the joining method in Embodiment 1 The figure explaining the heat conduction in joining in the joining method of Embodiment 1 The figure explaining the beam mode in Embodiment 1 The figure explaining the laser irradiation through the pressurization tool in Embodiment 2 Process sectional drawing which shows the joining method in Embodiment 3 Process sectional drawing which shows the joining method in Embodiment 4 FIG. 6 illustrates a structure of a joined body in Embodiment 5. FIG. 6 illustrates a structure of a joined body in Embodiment 6. Schematic sectional view for explaining a conventional joining method and joining apparatus

First, the main points of the invention will be described.
In the joining method according to the present invention, when joining the first member and the second member, a ceramic pressure member that absorbs 10 to 40% of the laser light and generates heat and a second material such as a copper plate are used. In a state where the first member such as a copper wire is sandwiched between the members, the pressing member is irradiated with laser, and the first member and the second member are heated by the laser beam that has passed through the pressing member, and at the same time, the laser beam The pressure member is heated by heating, the first member is heated and softened by heat transfer from the pressure member, and then pressurized, thereby deforming the first member into a flat shape, and the first member and the second member The contact area is increased for bonding.

  Thus, the first member is heated and deformed into a flat shape by pressing the first member while the first member is softened by heating the first member by heat transfer from the pressure member. Since the contact area of the second member increases, the amount of heat conduction to the second member can be increased, the first member and the second member can be strongly heat diffusion bonded, and a strong and stable high-quality bonding can be achieved. realizable.

  At this time, when the first member such as a copper wire is deformed into a flat shape and heat conduction to the second member is increased, and copper that reflects 95% or more of the laser beam that has passed is used as the first member, It can also be set as the structure which reheats the pressurization surface of a pressurization member by the laser beam reflection in a joining interface.

  With this configuration, the heat dissipation effect due to heat conduction to the second member is compensated and stable bonding is possible. In addition, since the laser power attenuates while passing through the pressure member that partially passes the laser, the temperature rise on the pressure surface inevitably decreases, but so-called double-pass heating compensates for this, and the thermal gradient of the ceramic pressure member By reducing the strain caused by this and extending the service life, the bonding quality can be stabilized over a long period of time.

  Also, a resin-coated copper wire can be used as the first member. After the resin coated by heating from the pressure member that absorbs laser light and generates heat, the wire and the second member are bonded together. Join.

  In this case, the coated resin is vaporized at a stretch by heat conduction and heat rays from the ceramic pressure member that generated heat by the partial absorption of the polyurethane wire or enamel wire, and the laser beam that passed therethrough, and there is no pure resin. Strips of copper wire and enables high quality and stable bonding.

  Further, a material having a low thermal conductivity or a material having a low thermal conductivity so as to prevent the temperature of the joint from escaping to the surroundings on the pressure surface of the pressure member or the holding table surface supporting the second member, It is also possible to pre-coat a resin having the same quality as the resin-coated wire.

  By coating the holding surface of the second member under pressure with a low thermal conductor such as the same resin coat as the resin that has been vaporized in advance, the heat of the second member is suppressed and is strong and stable. The bonded quality can be maintained.

  Further, in the laser power when irradiating the pressure member with the laser beam, the laser power is gradually increased so that the entire temperature becomes a uniform temperature as long as the time permits, according to the heat conduction time of the heating member. The second laser power after the start of deformation may be larger than the first laser power before the start of deformation by the pressure member of the member.

  By gradually increasing the laser power, it is possible to secure the time required for the pressure member to conduct heat to the laser light exit side, while preventing an extreme temperature difference from the laser light entrance side, By dissipating heat from the pressure member to the first member, melting due to a rapid temperature rise at the laser light entrance surface of the pressure member can be prevented, so that stable bonding quality can be maintained.

  In addition, in order to shorten the time for the temperature of the bonding interface to reach the temperature required for bonding after the first member heats the second member, a surface opposite to the surface of the second member that contacts the first member in advance is provided. Heating with a laser, a heater or the like is also possible.

  Even if the second member is much larger than the first member and the temperature required to cause thermal diffusion bonding cannot be obtained only by heating by heat transfer from the first member, the second member is assisted heated. By doing so, it is possible to maintain strong and high-quality bonding.

Furthermore, an inert gas can also be supplied around the heating portion of the first member that is heated by the laser light that has passed through the pressure member.
By spraying an inert gas such as nitrogen gas on the laser light receiving surface of the pressure member, the laser light receiving surface not only prevents the oxidation of the ceramic and prolongs its life, but even a laser partially transmissive ceramic has a Because it becomes the highest temperature, the hot part can be cooled with inert gas, can be prevented from melting, and the temperature gradient at the laser inlet / outlet of the ceramic pressure member can be reduced, reducing thermal fatigue and stable for a long time The bonded quality can be maintained.

  A joined body in which a wire as a first member and a metal plate as a second member joined by the joining method described above are joined, and the surface roughness of the pressurizing deformed portion of the wire is affected by the thermal effect of the laser beam. The joined body is rougher than the surface roughness of the non-pressurized part.

  According to such a joined body, the wire is pressed by the condensing effect of the transmitted laser light by the edge formed by being pressed by a heated pressure member that partially absorbs the laser light. When the curvature of the edge portion formed in this way is larger than that of the pressure member or the surface roughness is reduced, the tensile strength of the joined body itself is increased, and high joining quality is obtained.

Alternatively, the first member may be heated by heat transfer from the pressure member, and the second member having a melting point lower than that of the first member may be softened so that the first member is embedded in the second member.
A first member such as a lead wire is sandwiched between a pressure member that partially absorbs the laser light and a second member such as solder, the laser is irradiated to the heating member, and the first light is irradiated by the laser light that has passed through the pressure member. At the same time as heating the member and the second member, the pressure member is heated with laser light, the first member is heated by heat transfer from the pressure member, and the first member such as solder having a melting point lower than that of the lead wire as the first member. By softening the two members and embedding the first member in the second member, high-quality joining without contact failure can be achieved.

  At this time, tin or a tin alloy such as solder is used as the second member, and a lead wire such as copper wire coated with polyurethane or the like is used as the first member, and the second member is transmitted from the first member to the coating decomposition temperature. The temperature may be raised with heat.

  Further, the second member is tin or solder, the first member is a lead wire coated with polyurethane, etc., and the second member is heated from the pressure member and the melting point of the coating material such as polyurethane from the passing laser beam. By heating higher, a high quality joint without contact failure can be achieved by embedding a copper wire in which the coating is peeled off and the surface oxidation is not so advanced.

  A joined body obtained by joining the wire, which is the first member joined by the joining method described above, and the second member, and a part of the surface of the wire embedded in the second member is pressed while contacting the first member. Since it is embedded in the second member, it is possible to make a joined body in which a part of the first member is exposed to the outside.

  A joined body of a wire, which is a first member joined by the second joining method, and a second member, wherein the joined body is tin or a tin alloy, and the wire is joined or joined without plastic deformation. Since it is embedded in the joined body and the surface shape of the pressure member is transferred, it is possible to confirm the embedding, the peeling of the coating, and the like by the appearance inspection, and the high joining quality can be confirmed from the appearance.

Embodiments of the present invention will be described below with reference to the drawings.
In the present invention, when joining two members, a pressure tool that partially transmits laser light and absorbs a part is used, and the first member is sandwiched between the pressure tool and the second member. By irradiating a member with a laser beam through a pressing tool while applying pressure, the pressing tool is heated by absorption of the laser beam, and the first member is crushed by the pressure and heat from the pressing tool. Thus, in the state where the contact area between the first member and the second member is enlarged, heat is generated by laser light irradiation, and the first member and the second member are bonded by thermal diffusion.

In each of the following embodiments, the joining method of the present invention for joining various members will be described, taking as an example the joining of copper wires and copper plates, or lands of a flexible substrate.
(Embodiment 1)
The first embodiment will be described below with reference to FIGS.

  FIG. 1 is a process cross-sectional view illustrating a bonding method according to the first embodiment, FIG. 2 is a diagram illustrating heat conduction during bonding in the bonding method according to the first embodiment, and FIG. 3 illustrates a beam mode according to the first embodiment. FIG.

  In the joining method in the present embodiment, as shown in FIG. 1, a polyurethane wire 4 is sandwiched between a pressing tool 2 that partially absorbs laser light 1 and a copper plate 3, and the pressing tool 2 is irradiated with the laser light 1. The polyurethane wire 4 and the copper plate 3 are heated by the laser beam 6 that has passed through the pressing tool 2, and at the same time, the pressing tool 2 is heated by the laser beam 1, and the polyurethane wire 4 is heated by heat transfer from the pressing tool 2. While deforming, the polyurethane coating 7 is melted and vaporized to expose the copper wire 8 whose surface is not oxidized, and the copper wire 8 is flattened by pressing and heating to increase the contact area with the copper plate 3. The wire 8 and the copper plate 3 are joined by thermal diffusion bonding. Thus, even if the copper wire 8 or the copper plate 3 reflects the laser beam 1 almost, the pressing tool 2 absorbs a part of the laser beam 1 and is heated, so that the irradiated laser beam 1 and the pressurization are pressed. The copper wire 8 is heated to a sufficiently high temperature by the heat from the rule 2, and the copper wire 8 can be heated to a temperature necessary for thermal diffusion bonding by an easy method. At the same time, since the copper wire 8 is pressed by the pressing tool 2, the copper wire 8 softened at a high temperature can be deformed into a flat shape, and the bonding area between the copper wire 8 and the copper plate 3 can be improved easily. In addition, the bonding strength can be improved.

Reference numeral 5 denotes a holding table that receives pressure from the pressing tool 2.
Here, as the pressurizing tool 2, ceramics that partially absorb laser light can be used as a material, and as the ceramic material, a blending with a laser absorption rate of 10 to 40% is suitable, and the size and shape of the tool Thus, the optimum absorption rate changes, and the absorption rate is determined as the optimum design parameter so that the whole can be heated as homogeneously as possible by taking the return light from the object to be pressurized into account.

Hereinafter, the bonding process will be described with reference to FIGS. 1 (a) to 1 (d).
FIG. 1A is a diagram at the start of laser irradiation in a pressurized state. In ordinary ceramics, the laser irradiation surface 9 absorbs or reflects most of the laser light 1, but the pressing tool 2 only partially absorbs the laser light 1. Therefore, for example, more than half of the laser beam 1 passes to the pressing surface 10 and the whole can be heated, so that the pressing surface 10 can be heated to a high temperature such as 1000 ° C. or more. In addition, the copper plate 3 around the polyurethane wire 4 is also slightly heated.

In the present embodiment, since the pressing surface 10 of the pressing tool 2 is heated to near the melting point of the copper wire 8, the copper wire 8 starts to be deformed by heat and pressure.
In FIG. 1B, the coating 7 is melted and vaporized while the polyurethane wire 4 is deformed, and the copper wire 8 is exposed. Since the heating proceeds in this state, the copper plate 3 is directly heated.

  As shown in FIG. 1 (c), the temperature of the copper wire 8 rises as a result of further irradiation with the laser beam 1, becomes a flat body 11 beyond the softening point, increases the contact area 12 with the copper plate 3, and reduces the thermal resistance. The copper plate 3 is efficiently heated, and the bonding interface 13 of the copper plate 3 rises to a temperature equivalent to that of the flat body 11.

  Finally, when both the copper wire 8 and the copper plate 3 at the bonding interface 13 are close to the melting point in FIG. Thus, the thermal diffusion bonding starts from FIG. 1B, and the thermal diffusion bonding is completed in FIG.

  In order to cause thermal diffusion bonding, it is necessary to apply a high pressure in order for copper atoms to cause thermal diffusion movement and integration at the bonding interface 13 between the flat body 11 and the copper plate 3. And although the unevenness | corrugation is formed in the surface of the copper wire 8 and the copper plate 3, since the uneven | corrugated convex part contacts and the high voltage is applied to the contact part, since it deform | transforms and integrates together, a contact part Thermal diffusion bonding occurs.

  Here, when the holding table 5 is deprived of heat, the temperature of the bonding interface 13 of the copper plate 3 does not rise to near the melting point of copper and the bonding strength is extremely lowered. It is preferable to coat 14.

It is obvious that if the holding table 5 is also heated in advance, the copper plate 3 is likely to reach a temperature necessary for causing the thermal diffusion bonding, and a better bonding can be performed quickly.
Further, when the pressure tool 2 is exposed to a high temperature condition for a long time, the deterioration of the pressure tool 2 is promoted. Therefore, since it takes time to raise the temperature of the polyurethane wire 4 and the copper plate 3 in the main joining process, the power of the laser 1 can be gradually increased, and the laser irradiation surface 9 and the pressure surface 10 of the heating tool 1 can be increased. Since the temperature gradient can be reduced and the temperature rise of the laser irradiation surface 9 of the pressurizing tool 2 can be suppressed, the life of the heating tool 2 can be extended. In the figure, the laser 1 is shown darker as it goes to FIGS. 1A to 1D, and this darkness shows the change in the laser power intensity Pt.

  Further, as a beam mode on the irradiation surface 9 of the laser 1 that irradiates the pressurizing tool 2, a Gaussian mode (FIG. 2A) in which the laser intensity P increases toward the center of the irradiation surface 9, and the laser intensity P is uniform. It is possible to use a top hat (FIG. 2 (b)), or a donut shape (FIG. 2 (c)) in which the laser intensity P at the center is low. Among these, use of a donut-shaped beam mode with a low laser intensity P at the center part is preferable because the temperature rise at the center part of the irradiation surface 9 is suppressed and the life of the pressing tool 2 can be extended. is there.

  In addition, it is efficient to adjust the irradiation width NA of the laser 1 so as to be almost the same as the length of the longest portion of the pressure surface 10, and laser leakage from the side surface can be reduced. It is difficult and suitable.

  Here, the case where the copper wire 8 is the polyurethane wire 4 has been described as an example, but the joining method and joining device of the present invention can be similarly applied even to a copper wire that does not form the coating 7. The same applies to the following embodiments.

FIG. 3 shows a change in the state of heat conduction at the start of production and stable production in joining the polyurethane wire 4 and the copper plate 3.
FIG. 3A shows the start of production. When the member to be joined is copper, the reflectance of the copper laser is 95% or more, so the reflected laser light from the copper wire 20 is mainly used from the pressurizing tool 2. Although the pressure receiving surface 16 of the flattened copper wire 20 is heated by the heat conduction, and the surface 17 of the copper plate 3 is heated to near the melting point by the heat conduction of the flattened copper wire 20, the thermal diffusion bonding occurs. At this time, the holder 5 is deprived of heat, and it is necessary to increase the power of the laser 1 and raise the temperature of the heating tool 2 to a higher temperature.

  Even in a state of stable production as shown in FIG. 3 (b), the polyurethane coating 7 (see FIG. 1) is vaporized, and the vaporized material 34, which is vaporized polyurethane vapor, diffuses to form the pressurizing tool 2 and the holding base. There is a concern that the bonding quality will change. Therefore, as shown in FIG. 3C, it is preferable to remove the polyurethane 19 attached to the pressing tool 2 by automatically applying paper every predetermined shot to stabilize the joining quality. Furthermore, since the polyurethane layer adhered to the holding base 5 acts as a heat insulating material 14 with the copper plate 3, it is possible to suppress a decrease in the bonding temperature, and since the production starts and exceeds 100 shots, the bonding strength is further increased. It was observed to be more stable. Therefore, it is preferable to coat the holding table 5 or the pressurizing tool 2 with a material having a lower thermal conductivity than the holding table 5 such as polyurethane or silicon in advance from the time of a new article.

  Although there was a concern that the tip of the pressurizing tool 2 was worn away by paper application, by automatically applying paper while the polyurethane layer 19 remains, it can be made almost maintenance-free without wear. Since the polyurethane layer 19 transmits almost all laser light, there is almost no change in the influence of the passed laser light.

In order to prevent the laser light receiving surface 27 of the pressurizing tool 2 from being deteriorated due to oxidation, it is preferable to perform laser irradiation while blowing an inert gas onto the laser light receiving surface 27.
(Embodiment 2)
Next, the joining method and joining apparatus of Embodiment 2 are demonstrated using FIG.

FIG. 4 is a diagram for explaining laser irradiation through the pressurizing tool in the second embodiment.
FIG. 4A shows a specific shape of one embodiment of the pressure tool 2. In order to receive the laser 1 efficiently, a light receiving surface larger than the laser spot 24 has a flange 25 for holding the heating tool 2 and an optical waveguide 22 slightly larger than the transmission part of the laser 1 is formed in the middle. Thus, since the light is reflected on the wall surface like an optical fiber, laser leakage to the surroundings 23 other than the pressing surface 10 is almost eliminated, and damage to the surrounding resin and the like by the laser is eliminated.

  FIG. 4 (b) shows that the laser beam that has passed through the pressing tool 2 is reflected by the surface of the copper plate in the near-infrared range of 800 nm to 1100 nm, which is used for normal processing, by nearly 98%. Most of the laser light is returned by reflection from the copper plate 3 and the pressing surface 10 of the pressurizing tool 2 is returned and re-laser heated by the laser light 26, so that the amount of generated heat increases nearly twice and can be heated efficiently. Show.

  PX graphs in FIGS. 4C and 4D show changes in the laser absorption amount P (W) at the position X (mm) from the flange 5 in the laser irradiation direction. The part indicates that the laser absorption amount P (W) is increased by the return laser beam 26.

  As described above, since most of the return light is absorbed by the pressurizing tool 2 and used for reheating, the laser light leaking to the periphery becomes extremely small, and JIS 6802: 2005 is provided without providing a special laser safety cover. Laser safety standards such as CLASS1M can be easily satisfied.

The laser leakage 29 is constantly monitored by the pin photodiode 28. If the pressurizing tool 2 is broken and the laser beam leaks, the laser is stopped before the laser safety level is exceeded. It is also possible.
(Embodiment 3)
Next, the joining method of Embodiment 3 is demonstrated using FIG.

FIG. 5 is a process cross-sectional view illustrating the bonding method according to the third embodiment.
In FIG. 5, in each of the above embodiments, the precoat solder 32 and the polyurethane wire 4 are sandwiched between the pressure tool 2 that partially absorbs the laser light 1 and the land 31 of the substrate 30, and the laser light 1 is applied to the pressure tool 2. The polyurethane copper wire 4 and the precoat solder 32 are heated by the laser beam 6 that has been irradiated and passed through the pressurizing tool 2 to decompose the polyurethane coating 7 into a melt 33 and a vaporized product 34, and pressurize with the laser beam 1. The tool 2 is heated, the copper wire 8 and the precoat solder 32 are heated via the pressurizing tool 2 to completely remove the polyurethane film 7, and the precoat solder 32 having a melting point lower than that of the copper wire 8 is softened and melted to obtain copper. A joining method in which the wire 8 is embedded in the precoat solder 32 in the same shape is shown.

  FIG. 5A is a diagram when pressurization and laser irradiation are started. As shown in FIG. 5B, as the pressurization / laser irradiation proceeds, the polyurethane film 7 is decomposed into a melt 33 and a vaporized product 34. Then, the stripped copper wire 8 begins to be hard to be hardened with the pre-coated solder 35 which has started to soften.

  FIG. 5 (c) shows a copper wire in which the surface of the polyurethane film 7 is not sufficiently advanced in a state where the polyurethane film 7 is completely removed and the copper wire 8 is exposed and heated to a temperature sufficiently higher than the solder melting point. 8 shows a state of being embedded in the molten solder 36. At this time, copper and solder are alloyed.

  FIG. 5D shows a state where the irradiation of the laser beam 1 is finished and the pressing tool 2 is returned. In this state, the precoat solder 35 becomes a solidified solder 37 having a shape to which the pressing tool shape is transferred. At this time, since the pressurized surface of the embedded copper wire 38 can be seen from the outside, it is possible to inspect the appearance of the polyurethane film 7 without peeling, without checking the X-ray cross section, so that high quality bonding can be maintained. it can.

In addition, by continuing laser irradiation even when the pressing tool 2 starts to be returned, the embedded copper wire 38 can be covered with solder by re-soldering and melting the surface with the laser beam that has passed.
(Embodiment 4)
Next, the joining method of Embodiment 4 is demonstrated using FIG.

FIG. 6 is a process cross-sectional view illustrating the bonding method according to the fourth embodiment.
FIG. 6 shows an embodiment in which the pressurizing tool 2 joins the two flexible substrates 50 and 53 by pressing and heating.

In FIG. 6, the precoat solder 52 is formed in advance on the land 51 of the flexible substrate 50 as the first member and the land 54 of the flexible substrate 53 as the second member during reflow.
The resin sheets 55 and 57 of the flexible substrates 50 and 53 have laser transmittance and laser partial absorption characteristics with respect to the wavelength of a normal semiconductor laser of 600 to 1500 nm.

Next, the joining process will be described with reference to FIGS. 6 (a) and 6 (b).
FIG. 6A is a view immediately before the pressing tool 2 is irradiated with the laser 1 when the pressing tool 2 sandwiches the flexible substrate 50 with the flexible substrate 53.

  FIG. 6B shows that the pressing tool 2 partially absorbs the laser beam 1 and becomes a temperature higher than the melting point of the solder, and the laser beam passing through the pressing tool 2 is partially absorbed by the resin sheet 57 of the flexible substrate 53. At the same time, the land 51 is raised to a temperature sufficient for melting the solder by the laser light transmitted through the heat conduction, and the solder 52, the land 54, and the resin sheet 55 that are pre-coated by the laser light, the heat conduction, and the radiant heat. Since heating is performed in a pressurized state, the precoat solder 52 is melted and the two lands 51 and 53 are joined by solder.

In addition, since the resin sheets 55 and 57 generate heat themselves and heat the lands 51 and 54, wettability is improved, and high-quality solder bonding can be performed.
Further, before pressing, the laser beam 1 may be started to preheat the pressurizing tool 2 and the flexible substrates 50 and 53, or laser irradiation may be started after the flexible substrates 50 and 53 are heated by another method. The flexible substrates 50 and 53 can be joined robustly and easily by preheating.

  In addition, by incorporating a temperature sensor such as a thermocouple 56 into the pressurizing tool 2, temperature control can be accurately performed. This prevents the flex board from becoming a problem with ordinary laser soldering, and enables extremely high quality bonding. It can be kept stable.

It is obvious that the lands of the flexible boards 53 and 50 are soldered together even if the two flexible boards 53 and 50 are replaced.
(Embodiment 5)
Next, a joined body using the joining apparatus or joining method of each of the above embodiments will be described with reference to FIG.

7A and 7B are diagrams for explaining the structure of the joined body in the fifth embodiment, in which FIG. 7A is a top view, FIG. 7B is a side view, and FIG. 7C is an enlarged view of an R portion. .
FIG. 7 shows a joined body in which the polyurethane wire 4 is joined to the copper plate 3, the coating 7 is removed by heating in the vicinity of the joined portion of the polyurethane wire 4, and the exposed copper wire 8 is deformed by pressurization. A flat portion 46 is formed. The flat portion 46 is a portion that is sufficiently thinly deformed flat by the pressing tool 2.

  As described above, by flattening the copper wire joints, it becomes possible to perform thermal diffusion bonding in a state where the joint area is enlarged, so gold plating, copper, etc. with high laser reflectivity with a simple configuration These various bonding materials can be bonded at high speed, high quality and high stability. In addition, it becomes easy to make the temperature of the joint part higher than the melting point of the joining material, and it becomes possible to join in a liquid surface shape, so it is possible to form a high-quality joined body with few scratches and fine cracks. Become.

  In this heating method, since the laser beam 1 is focused on the edge r of the pressurizing tool 2, the curvature of r is increased, the surface is melted, the surface roughness is reduced, and the breaking strength is increased. Highly reliable and strong bonding can be realized.

The melted coating 7 is observed as a polyurethane shrinking portion 65 which shrinks as it evaporates and shrinks when the copper wire 8 is exposed.
Since the r portion of the pressurizing tool 2 condenses the laser beam that has passed through the inside to the R portion like a convex lens, the temperature of the flat portion 46 rises to the vicinity of the melting point where the thermal diffusion bonding has already occurred at the bonding interface 47 of the copper plate 3. The R part partially exceeds the melting point of copper and becomes a liquid surface shape having a smooth R. Since there is no scratch or fine crack and the tensile strength of the R part is increased, the quality as a joined body is improved. .
(Embodiment 6)
Next, another structure of the joined body using the joining device or joining method of each of the above embodiments will be described with reference to FIG.

FIG. 8 is a diagram for explaining the configuration of the joined body in the sixth embodiment, and shows an example of a joined body of the polyurethane wire 4 and the precoat solder 35 joined by the joining method of the third embodiment.
The bonded body of the sixth embodiment is characterized in that a part of the exposed portion 43 on the surface of the copper wire 38 embedded in the precoat solder 35 can be observed from the outside.

In addition, as embodiment, various forms may be sufficient as follows.
As an example of the above embodiment, an example in which copper of the same kind of metal is bonded by thermal diffusion using a solder having a melting point of copper or lower is shown. However, even when different metals such as copper and nickel are bonded, Thermal diffusion bonding can be performed between materials having melting points higher than the melting point. In addition, by heating the pressurizing tool 2 to a temperature exceeding the melting point of copper, welding may be performed so as to embed a copper wire in the molten copper without using solder. When different metals can be heated to a melting point or higher than the melting point under pressure, they can be joined so as to embed the other metal in one molten metal. Of course, bonding is possible without a polyurethane coating.

Further, even when a non-metal such as resin or glass can reach the vicinity of the melting point in a pressurized state, it can be joined by applying pressure and heat.
Further, although the polyurethane-coated wire has been described as the second member, an insulating coating such as an enameled wire may be used, and even a thin plate can be joined by supplying a necessary temperature from the heating tool 2 for joining.

  In addition, although an example in which a copper wire is sandwiched between precoat solder and heated and pressed with a pressure tool has been shown, solder plating or tin plating may be used in place of precoat solder, and alloys other than copper wires will not be alloyed Since metal is mechanically embedded, electrical conduction is ensured, so it is effective as a joint.

  The present invention is capable of bonding various bonding materials such as gold plating and copper having a high laser reflectivity with a simple structure at high speed, high quality and high stability. This is useful for a joining method, a joining apparatus, a joined body, and the like for joining two members.

DESCRIPTION OF SYMBOLS 1 ... Laser beam 2 ... Pressing tool 3 ... Copper plate 4 ... Polyurethane wire 5 ... Holding stand 6 ... Laser beam 7 ... Coating 8 ... Copper wire 9 ... Laser irradiation surface 10 ... Pressure surface 11 ... Flat body 13 ... Junction interface 14 ... Heat insulation 15 ... Polyurethane layer 16 ... Surface 17 ... Surface 19 ... Polyurethane 20・ ・ ・ Copper wire 22 ・ ・ ・ Optical waveguide 24 ・ ・ ・ Laser spot 25 ・ ・ ・ Head 26 ・ ・ ・ Return laser beam 27 ・ ・ ・ Laser light receiving surface 28 ... Pin photodiode 29 ... Laser leakage 30 ... Substrate 31 ... Land 32 ... Precoat solder 33 ... Mold 34 ... Vaporized 35 ... Precoat solder 36 ... Mold solder 37 ... Solidified solder 38 ... Copper Wire 46 ... Flat part 47 ... Bonding interface 5 53 ... Flexible boards 51, 54 ... Land 52 ... Solder 55, 57 ... Resin sheet 56 ... Thermocouple 65 ... Polyurethane shrinkage 103 ... Lead 105 ... Electrode pad 115 ... Bonding tool 116 ... Ultrasonic horn 117 ... Upper end surface 118 ... Pressure surface

Claims (9)

A pressure tool that absorbs part of the laser light and transmits the remainder of the laser light to irradiate the first member;
A holding table on which the first member and the second member are placed, and the first member is sandwiched between the pressing tool and the second member via the pressing tool; While irradiating the first member with the laser beam and pressurizing the first member with the pressurizing tool, the first member is heated, pressed and crushed, and the first member and the second member the contact area is thermally diffused bonding the second member and the first member in enlarged state, welding apparatus wherein the laser beam absorption rate of the pressure tool, characterized in 10-40% der Rukoto . A pressure tool that absorbs part of the laser light and transmits the remainder of the laser light to irradiate the first member;
A holding table on which the first member and the second member are placed, and the first member is sandwiched between the pressing tool and the second member via the pressing tool; While irradiating the first member with the laser beam and pressurizing the first member with the pressurizing tool, the first member is heated, pressed and crushed, and the first member and the second member The first member and the second member are bonded by thermal diffusion in a state where the contact area is expanded, and a material having a lower thermal conductivity than the holding table is previously applied to the pressing surface of the pressing tool or the holding table surface. joining apparatus according to claim coat to Rukoto. Placing the second member on the holding table and placing the first member on the second member;
A step of sandwiching the first member between a pressure tool that absorbs part of the laser light and transmits the remainder of the laser light and the second member;
Irradiating the first member with the laser beam through the pressurizing tool and pressurizing the first member with the pressurizing tool, and heating by absorbing a part of the laser beam. While the first member is crushed by the heat and pressure of the applied pressure tool, the first member and the second member are bonded by thermal diffusion, and the absorption rate of the laser light of the pressure tool is 10 to 40. bonding wherein the% der Rukoto. Placing the second member on the holding table and placing the first member on the second member;
A step of sandwiching the first member between a pressure tool that absorbs part of the laser light and transmits the remainder of the laser light and the second member;
Irradiating the first member with the laser beam through the pressurizing tool and pressurizing the first member with the pressurizing tool, and heating by absorbing a part of the laser beam. The first member and the second member are heat diffusion bonded while crushing the first member by the heat and pressure of the pressed tool, and the first member is a wire coated with a resin, after the resin is thermally decomposed by heating, bonding wherein that you bonding the said wire second member. The bonding method according to claim 4 , wherein the pressure surface of the pressure tool or the surface of the holding table is coated with a material having a lower thermal conductivity than the holding table or the resin. Placing the second member on the holding table and placing the first member on the second member;
A step of sandwiching the first member between a pressure tool that absorbs part of the laser light and transmits the remainder of the laser light and the second member;
Irradiating the first member with the laser beam through the pressurizing tool and pressurizing the first member with the pressurizing tool, and heating by absorbing a part of the laser beam. While the first member is crushed by the heat and pressure of the pressed tool, the first member and the second member are bonded by thermal diffusion bonding, and the laser beam irradiation is gradually performed. bonding wherein the raised Rukoto. The joining method according to any one of claims 3 to 6 , wherein a back surface of the second member with respect to a surface in contact with the first member is heated before the pressurization. The bonding method according to any one of claims 3 to 7 , wherein an inert gas is supplied around the heating portion of the first member when the laser beam is irradiated. The joining method according to any one of claims 3 to 8 , wherein a return light of the laser light generated at an interface between the first member and the pressing tool is also used during the heating.

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