JPH029433B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a bonding structure for an automobile window glass terminal, and more specifically, the present invention relates to a bonding structure for an automobile window glass terminal, and more specifically, a terminal for an automobile window glass is bonded to a bus bar baked on the automobile window glass using solder having a specific composition. Regarding the structure. (Prior technology) Generally, the rear window glass of automobiles is made of Ag.
By printing the paste in a predetermined pattern and baking it, the anti-fog hot wire and the strip-shaped bus bar connecting both ends of the hot wire are formed.
Then, a power supply terminal is attached to this bus bar by soldering. (Problem to be Solved by the Invention) In this mounting method, molten solder is interposed between the surface of the busbar and the back surface of the terminal, and the solder is solidified to join the terminal and the busbar. Since the coefficients of thermal expansion of the glass and the glass are different, stress will remain in the joint after joining. In particular, such residual stress is concentrated at the joint edges. Furthermore, stress due to vibrations and the like occurring while the vehicle is running tends to concentrate on the edge portions. Therefore, residual stress and stress due to external force etc. act on the joint edge at the same time.
This may cause cracks in the plating applied to the busbar, or the glass itself may be destroyed. Therefore, an object of the present invention is to provide a bonding structure for an automobile window glass terminal free of such defects. (Means for Solving the Problems) In order to solve the above problems, the present invention has a Pb content of 55% to 85% by weight, a Bi content of 5% to 20% by weight, and the balance is Sn. A metal terminal having a pair of spaced apart protrusions on the back surface of the pedestal is joined to a conductive element using solder containing 0.3 mm to 0.6 mm in thickness. (Function) According to the configuration of the present invention described above, the Pb content can be reduced to 55
Since the terminals are bonded using soft solder with a thickness of 0.3 mm to 0.6 mm, the solder layer has a thickness of 0.3 mm to 0.6 mm, so the residual stress generated at the joint and the stress caused by external force are alleviated by this solder layer. be done. Also, since the solder contains Bi, this Bi
As a result, the melting temperature of the solder containing a large amount of Pb is lowered, and the generation of residual stress at the terminal joint is reduced as much as possible, and the generation of stains due to discoloration of the printed wire made by baking the Ag paste is prevented.
Furthermore, the working temperature range for soldering becomes wider. Furthermore, when the solder contains Ag, formation of an alloy between the Ag in the printed wire and the metal in the solder is prevented. (Example) Preferred examples of the present invention will be described in detail below based on the accompanying drawings and tables. Fig. 1 shows a rear window glass of an automobile to which terminals are attached using the bonding structure according to the present invention, in which hot wires 2 with a width of 1 mm or less are baked at equal intervals in the width direction of the back surface of the rear window glass 1. Furthermore, band-shaped busbars 3, 3 having a width of about 10 mm are baked to connect both ends of these hot wires 2, and power supply terminals 4, 4 are bonded to the center portions of the busbars 3, 3. When power is supplied to the busbars 3, 3 through the terminals 4, 4, Joule heat is generated in the hot wires 2... and the glass 1
cloudiness is removed. To form such hot wires 2 and bus bars 3, first, fine Ag particles and low melting point glass powder are made into a paste using a solvent, and this Ag paste is applied to the surface of the glass 1 using a screen plate having a predetermined pattern. After drying this printed Ag paste, it is heated and baked at approximately 700℃. Then, the terminals 4 are soldered to the baked bus bar 3. As shown in FIG. 2, this terminal 4 has legs 6, 6 extending from both ends of a terminal main body 5, and pedestals 7, 7 are integrally provided on the legs 6, 6.
A pair of protrusions 8, 8 are formed spaced apart on the back surface of the main body 5, and a male connecting piece 9 is bent at a substantially right angle from one end of the main body 5. In order to join such a terminal 4 to the bus bar 3, a third
As shown in the figure, heated and molten solder is poured between the back surface of the pedestal 7 and the surface of the bus bar 3, and is solidified. That is, the above solder is Pb
The content ratio is 55% to 85% by weight, and the remaining
A soft solder containing Sn is used, and the solder layer 10
The thickness of the solder layer 10 is set to 0.3 mm to 0.6 mm, and the end portion of the solder layer 10 is made to protrude from the periphery of the pedestal 7, and this protruding portion 10a is shaped to widen toward the end, so that the solder layer 10 and the surface of the bus bar 3 are smooth. I try to make it continuous. Using solder having the above composition, the terminal 4
Table 1 shows the results of an H-F (hammer fall) test on the strength of the glass when bonded to the bus bar 3. The hammer used in the H/F test was made of neoprene and weighed 2 kg. The numbers in the table indicate the number of broken glasses.
Here, the soft solder in Table 1 contains 73% by weight of Pb and 73% by weight of Bi.
The composition is 10% by weight, 15% by weight of Sn, and 2% by weight of Ag, and the current hard solder has a composition of 37% by weight of Pb.
It is a eutectic solder with Sn content of 65% by weight.

【table】

[Table] As is clear from the table above, the glass strength when using soft solder is superior to that when using conventional hard solder, and the thickness of the solder layer is reduced to 0.5.
mm, and if it is made thicker than usual, the strength will further improve. The table also shows the results of H/F tests with various solder layer thicknesses.

[Table] As is clear from the table, the thickness of the solder layer is 0.3mm.
A suitable value is 0.6 mm to 0.6 mm. Furthermore, the results of H/F tests with various solder compositions are shown in the table. Note that the thickness of the solder layer in this case is 0.5 mm.

[Table] As is clear from the table, the Sn content is high,
Glass with terminals bonded using so-called hard solder with a low Pb content has poor strength;
In other words, a glass plate with terminals bonded using solder with a high Pb content has excellent strength. From the table, the Pb content is approximately 55% by weight.
It has been found that a content of 85% by weight is suitable for obtaining the desired strength. Figure 4 shows the plated busbar 3 and the pedestal 7.
A terminal 4 with protrusions 8, 8 provided on the back surface and a terminal without protrusions were bonded together, and the adhesion strength against vertical tensile force was compared. As is clear from FIG. 4, by providing a protrusion on the back surface of the pedestal 7, the adhesive strength of the terminal to the bus bar 3 can be improved. Furthermore, if the Pb content is increased to make the solder softer, the solder will not melt unless the soldering temperature is 260° C. or higher, as shown in FIG. As a result, there is a risk that the busbar at the soldering location may deteriorate and the adhesive strength may become weak, or the busbar at the soldering location may change color and cause stains. For this reason,
In another embodiment of the present invention, solder to which Bi (bismuth) is added is used. That is, as shown in FIG. 6, when Bi is added to the solder, the melting temperature of the solder is lowered to about 220° C., making it possible to avoid the disadvantages of high-temperature soldering and widen the working temperature range. It's like that again
As shown in the table below, the glass strength when terminals are bonded using Bi-added solder alleviates residual stress and stress due to external force, and maintains good strength.

[Table] Also, as shown in Figures 5 and 6, Ag is added to the solder.
The adhesive strength against vertical tensile force differs between those with and without the addition of . That is, when a terminal is bonded to a bus bar using solder that does not contain Ag, the Ag in the bus bar and the metal in the solder form an alloy, resulting in weak bonding strength. However, if Ag is added to the solder, the busbar
Bond strength can be increased without Ag forming an alloy. The amount of Ag added is shown in Figures 5 and 6.
As is clear from the figure, the content is preferably 4.5% by weight or less. Although the case where the terminals are bonded to the bus bar baked on the rear window glass of a car has been described above, the bonding structure according to the present invention can also be applied to a bus bar baked on the side window glass of a car, an antenna element, a sensor element, etc. Of course, the present invention can also be applied to the case where a terminal is bonded to a conductive element. (Effects of the Invention) As is clear from the above description, according to the present invention,
Pb is used in conductive elements made by baking Ag paste.
The terminals are bonded using soft solder containing 55% to 85% by weight, and the thickness of the solder layer is increased to 0.3mm to 0.6mm, which reduces the residual stress generated in the terminal joints. , the stress caused by external forces acting intensively on the joint can be sufficiently alleviated, and the strength of the glass on which the conductive element is baked can be dramatically improved. In addition, since the content of Bi in the solder is between 5% and 20% by weight, the liquidus temperature of the solder is lowered, the adhesive strength of the printed wire is increased, and the working temperature range for soldering is widened. Residual stress has many advantages, such as being able to effectively prevent glass breakage due to concentration of stress due to external force. Furthermore, if Ag is included in the solder,
The adhesive strength can be further improved, and the effect of preventing glass breakage is further enhanced.

[Brief explanation of drawings]

The drawings show a preferred embodiment of the present invention, and FIG. 1 is a front view of a rear window glass of an automobile to which a terminal is attached by the joining structure according to the present invention, and FIG. 2 is a perspective view of the terminal. Figure 3 is a longitudinal side view showing the bonding structure of the terminal, Figure 4 is a graph comparing the adhesive strength against vertical tensile force of the terminal, and Figure 5 is when the terminal is bonded using solder that does not contain Bi. Graph showing the relationship between vertical tensile force and iron temperature. FIG. 6 is a diagram similar to FIG. 5 in which terminals are bonded using solder containing Bi. In addition, in the drawing, 3 is a conductive element, 4 is a metal terminal,
10 is a solder layer.

Claims (1)

[Scope of Claims] 1. A conductive element formed by baking an Ag paste made of fine Ag particles and low-melting point glass powder into a paste form using a solvent on an automobile window glass;
In a structure for joining a metal terminal provided with a pedestal to be soldered to the conductive element, a pair of protrusions are provided spaced apart on the back surface of the pedestal provided on the metal terminal, and the metal terminal and the above and a conductive element,
The content of Pb is 55% to 85% by weight, the content of Bi is 5% to 20% by weight, and the remaining part is solder containing Sn, and the thickness of the solder layer is 0.3mm to 0.6mm. A bonding structure for an automobile window glass terminal, characterized by the following. 2. The joining structure for an automobile window glass terminal according to claim 1, wherein the solder contains 4.5% by weight or less of Ag.