JPS5936995A - Method of coating solder on circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for coating a wiring board with a single solder.

As a method of applying solder coating to the surface electrode portion of a wiring board 1, for example, a ceramic wiring board, a ceramic wiring board 1 having a surface electrode 2 formed thereon as shown in FIG. After holding it with the lower jig 4 and immersing it in the solder bath [7], it is pulled upward while blowing compressed air 6, but since this compressed air 6 is blown in the direction of arrow A, it is not exposed to the wind. Solder and molten solder scatter and adhere to other solder-coated areas, creating solder puddles 7 as shown in Figure 3.When this solder puddle 7 occurs, the surface height increases. 9. There is a drawback that the component hole becomes small, making it difficult to attach external components and insert lead wires.In FIG. 2, 5 is a nozzle that blows out compressed air.

An object of the present invention is to provide a method for coating a wiring board with solder to reduce or prevent the occurrence of solder pools.

The present inventors conducted various studies regarding the above-mentioned drawbacks, and found that
The part of the wiring board to be solder coated is located at the lower end of the wiring board that contacts the wiring board, and the angle between the outward extension surface and the side wall is 40 degrees or less, and above the intersection line of the inward extension surface and the wiring board. The upper jig is provided with an inclined part to prevent the upper end from contacting the wiring board, and the angle between the outward extension surface and the side wall is 45 degrees or less and is below the intersection line of the inward extension surface and the wiring board. It is held between a lower jig with a sloped part so that the part to be solder coated is not located, and after immersing it in a solder bath, it is pulled upward while blowing compressed air to coat the surface electrode part of the wiring board with solder. As a result of applying this method, it was found that 17j soldering did not occur.

The present invention relates to a method in which a wiring board on which surface electrodes are formed is held between upper and lower jigs and soldered. The upper jig has a sloped part so that the angle is 40 degrees or less and the part to be solder coated is not located above the line of intersection between the inner extension surface and the wiring board, and the outer part of the upper end that comes into contact with the wiring board is By using a lower jig with an inclined part so that the angle between the inner extension surface and the side wall is less than 4s degrees, and the part to be solder coated is not located below the intersection line between the inner extension surface and the wiring board. This invention relates to a solder coating method for a wiring board, which is clamped, immersed in a solder bath, and then pulled upward while blowing compressed air.

In the present invention, the materials used for the surface electrode include materials with good solderability such as tungsten, molybdenum, copper, nickel, and silver-palladium, and the materials used for the stationery include solder such as aluminum, stainless steel, and titanium. It is preferable to use a material that does not adhere and is stable against flux and heat treatment.

The upper jig used for holding the wiring board in the present invention has an angle between the outer extending surface and the side wall of the lower end that contacts the wiring board is 40 degrees or less, and the angle between the inner extending surface and the wiring board is 40 degrees or less. It is necessary to provide an inclined part so that the part to be solder coated is not located above the intersection line, and the lower jig must have an angle between its outward extension surface and the side wall at the upper end that contacts the wiring board. It is necessary to provide the sloped portion at an angle of 45 degrees or less so that the portion to be coated with solder is not located below the line of intersection between the inwardly extending surface and the wiring board. If this condition is not met, solder pools will occur, making it impossible to achieve the object of the present invention.

In addition, in the L lower jig used for holding the wiring board, the outwardly extending surface is the part B shown in FIG. 4, and the inwardly extending surface is the part C.

Part of side wall melting D is shown.

Although there is no particular restriction on the angle at which the compressed air is sprayed, it is preferable to spray the compressed air at an angle of 30 to 45 degrees to the wiring board.

The present invention will be explained below with reference to Examples.

Embodiment 1 As shown in FIG. 5, a ceramic wiring board 1 with tungsten electrodes baked on its surface and then nickel plated is placed at the lower end that contacts the ceramic wiring board 1 at an angle between its outwardly extending surface and the side wall. The upper end of the upper jig 3 is in contact with the ceramic wiring board 1 and the upper jig 3 has an inclined part where β is 40 degrees and the part to be solder coated is not located above the intersection line between the inward extension surface and the ceramic wiring board 1. A sloped portion is provided in such a way that the angle α between the outwardly extending surface and the side wall is 45 degrees, and the portion to be coated with solder is not located below the intersection line between the inwardly extending surface and the ceramic wiring board 1. Hold it between the lower jig 4 and immerse it vertically in a flux (1,000-jet solder bath).
'#L, After 4 seconds, compressed air at 220°C was blown onto the ceramic wiring board 1 at a pressure of 3.5 Kg/cm through a 0.3 mm slit at an angle of 40 degrees, and then cooled. After cooling, it was removed from the jig and the solder pools on the surface electrode 2 were observed.As a result, the upper solder pool was 1 point, the lower solder pool was O, and there was 1 solder pool out of a total of 90 points on the surface electrodes. .

Embodiment 2 As shown in FIG. 6, the lower end of the upper jig 3 that comes into contact with the ceramic wiring board 1 has an angle rk formed between its outwardly extending surface and the side wall.
The method was the same as in Example 1, except that an inclined part was provided at the upper end of the lower jig 4 that was in contact with the ceramic wiring board 1 at an angle α of 45 degrees between the outward extension surface and the side wall. A solder coating was applied to the surface electrode 20 portion of the ceramic wiring board 10 under similar conditions.

Next, when this product was observed for solder deposits on the surface electrode 2 portion after being coated with solder, it was found to be 0 out of a total of 90 points for the surface electrodes.

Example 3 The lower end of the upper jig 3 that comes into contact with the ceramic wiring board l shown in FIG. A portion of the surface electrode 2 of the ceramic wiring board 10 was prepared in the same manner and under the same conditions as in Example 1, except that an inclined portion with an angle α of 45 degrees between the outward extension surface and the side wall was provided at the abutting upper end portion. A solder coat was applied.

Next, when I observed the solder pool on the surface of this product after solder coating (electrode 2), I found that it was 0 out of a total of 90 points for the surface electrode.
Met.

Comparative Example 1 As shown in FIG. 8, the lower end of the upper jig 3 that comes into contact with the ceramic wiring board 1 is provided with an inclined part with an angle α of 45 degrees between the outward extension surface and the side wall. A solder coating was applied to the surface electrode 2 portion of the ceramic wiring board 1 in the same manner and under the same conditions as in Example 1, except that the same as the conventional one was used without providing the sloped portion.

Next, when I observed the solder pool on the surface electrode 20 part after the solder coating of this product, the upper solder sag was 10.
Solder puddles appeared at five points, and there were five solder puddles that appeared to be caused by splashing from the flat part above.

Solder puddles occurred at 15 points out of a total of 90 points on the surface electrodes.

Comparative Example 2 As shown in FIG. 9, the lower end of the upper jig 3 that contacts the ceramic wiring board 1 has an angle α of 45 degrees between its outwardly extending surface and the side wall, and the ceramic wiring board 1 of the lower jig 4 The surface electrode 2 of the ceramic wiring board 1 was prepared in the same manner and under the same conditions as in Example 1, except that an inclined part with an angle α of 45 degrees between the outward extension surface and the side wall was provided at the upper end part to be in contact with. A solder coat was applied to the parts.

Next, when I observed the solder puddles at pole 2 on the surface of this product after solder coating, I found that the solder puddles on the top were 1.
One point occurred, and there were no shard accumulations below, and 11 points out of a total of 90 points on the surface 1d pole occurred.

In the embodiment, the solder coating method for a ceramic wiring board has been described, but the method can also be applied to other wiring boards.

The method of solder coating a wiring board according to the present invention includes:
The lower end that contacts the wiring board is sloped so that the angle between the outer extension surface and the side wall is 40 degrees or less, and the part to be solder coated is not located above the line of intersection between the inner extension surface and the wiring board. The upper jig and the upper end part that contacts the wiring board shall be coated with solder so that the angle between the outer extension surface and the side wall is 45 degrees or less and is below the intersection line of the inner extension surface and the wiring board. The solder pool is held between a lower jig and a lower jig with an inclined part so that the desired part is not located, and then immersed in a solder bath and then pulled upwards while blowing compressed air to remove the solder puddles on the two side poles of the wiring board. It is something that can be reduced or prevented.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a ceramic wiring board for explaining the present invention, FIG. 2 is an explanatory diagram of a final solder coating method for explaining the present invention, FIG. 3 is a side view showing the state of solder puddles, and FIG. FIG. 4 is a cross-sectional view of the jig, and FIGS. 5 to 9 are cross-sectional views showing a state in which a wiring board is held between the jig. FIGS. 5, 6, and 7 relate to one embodiment of the present invention. , 8 and 9 show the conventional method. Explanation of symbols 1...Ceramic wiring board 2...Surface electrode 3...
Upper jig 4... Lower jig 5... Nozzle
6...Compressed air 7...Solder pool 'f) + Fig. Z 2nd port 1 Koma 3 Fig. 4 Ward\i 5 Fig. Otsuguchi Yl 7 Fig.)

Claims (1)

[Claims] 1. In a method of applying solder coating to a wiring board on which surface electrodes are formed by holding it between upper and lower jigs. The lower end of the wiring board that comes into contact with the wiring board is such that the angle between the outer extension surface and the side wall is less than 40 degrees Jl, and the part to be solder coated is above the intersection line of the inner extension surface and the wiring board. The upper jig is provided with an inclined part so as to prevent the upper end from contacting the wiring board, and the angle between its outward extension surface and the side wall is 45 degrees or less, and from the line of intersection between the inward extension surface and the wiring board. A wiring board characterized by being held between a lower jig and a lower jig having an inclined part so that the part to be solder coated is not located below, immersed in a solder bath, and then pulled upward while being blown with compressed air. Solder coating method.