JPS60169193A - How to supply preliminary solder to the 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 [Technical Field of the Invention] The present invention relates to a method for supplying preliminary solder to a circuit board on which electronic components are mounted.

[Prior art]

In recent years, due to the demand for higher density electronic devices, the number of various surface-mounted components has increased and various active and passive electronic components, including ultra-large scale integrated circuits, have been actively miniaturized.

Therefore, the electrode dimensions of electronic components and their arrangement pitches are required to be extremely fine, and the soldering on the wiring of the circuit board on which they are mounted also needs to be highly accurate. There is.

As an example of mounting such an electronic component, a flip chip 0. Tape carrier 0. There are other hybrid EO implementations besides chip capacitors.

Conventionally, methods for supplying preliminary solder to a circuit board necessary for mounting such electronic components include a solder dipping method, a solder paste method, and a solder pole method.

The solder immersion method is a method in which the circuit board to be mounted is immersed in a solder bath in advance for pre-soldering, and the immersion conditions (
There were problems such as the relative relationship between the wiring pattern (pulling conditions) and the wiring pattern, and the elution of the wiring conductor into the solder base material, making it impossible to obtain a stable amount of solder.

In addition, the solder ball method is a method in which solder balls of various composition particles with a diameter of about 1 to 1 mm are arranged and mounted on a circuit board or component, and the variation in the diameter of the solder balls is 5 to 1 mm.
% or more, the price is high, and the handling of microspheres is difficult.

When using a mixture of solder balls of various diameters.

It is not practical as it is more troublesome.

Therefore, methods using solder paste printing, which are less problematic than these methods, are often used.

By solder paste printing. A conventional method of supplying preliminary solder to a circuit board is shown in FIGS. 1 and 2, which are perspective views and cross-sectional views of a printing device.

In the figure, (1) is a circuit board printed with solder paste, (2) is a frame consisting of four sides, (3) is a screen fixed and stretched on this frame, and the pattern (4) is opened and the other parts are It is covered with a resin film. (5) is a squeegee made of rubber material, and (6) is a solder paste placed on the screen (3).

The conventional preliminary solder supply method using solder paste printing was performed as follows. : First, the screen (3) is aligned on the circuit board (1) to be printed.

Next, place the solder paste (6) on the screen (3) and move the squeegee (5) in the direction of arrow A. The solder paste (6) will be rubbed on the screen (3), forming the pattern (4). Solder paste (6) is extruded downward and printed at the desired locations on the circuit board <1).

The above-mentioned screen formats include a mesh screen format, an open metal (no mesh) format, and a combination of these.

The particle size of the solder paste (6) is normally 325 mesh bus (approximately 30 to 40/Z), which is the limit of the fine particle size, so as shown in JP-A-56-16'7389 (printing method) There is a method that prints fine patterns using an open metal mask that does not get clogged due to mesh structure during extrusion.

Further, when the solder film thickness is the same as that of the screen (3), an open metal mask without a mesh structure can supply more solder paste (6).

In the above-mentioned conventional screen printing method, even with an open metal mask, the solder paste (6) particles cannot pass through fine patterned holes (for example, diameter 50 to 30 m+m) in the screen. The solder paste (6) adheres to the side wall of the pattern hole, and the printing efficiency (paste passage rate through the pattern hole) is 1 circuit board (1
) It decreases greatly depending on the material, the height of the pattern hole, etc.
The amount of solder was not uniform.

These factors also include screen and kenda paste (
In addition to the selection in 6), printing conditions, temperature, etc. also have an influence, and conventional methods have the disadvantage that quantitative pre-soldering of fine patterns is extremely difficult to meet the demands for high density and miniaturization.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the above-mentioned conventional method, and involves providing a solder paste supply pattern on a supply plate, filling the holes in this pattern with solder paste, placing it on a circuit board, and heating the supply plate. An object of the present invention is to provide a method for preliminarily supplying solder to a circuit board, in which a uniform amount of presolder can be applied in a fine pattern by melting solder paste and supplying the same onto two circuit boards.

[Embodiments of the invention]

FIG. 3 is a perspective view of a supply plate and a circuit board, showing a preliminary solder supply method according to an embodiment of the present invention. Ql) is a supply plate made of a transparent glass plate, and a wiring pattern (1a) is formed on the circuit board (1) on which a solder printing pattern @ is formed.

The preliminary solder supply method of the above-mentioned embodiment is as follows: First, the pattern (2) holes of the supply plate θ are filled with solder paste (6) by printing means or the like. Next, align and place this supply plate (1υ) on the circuit board (1),
Heat the supply plate 0.1). Then, the solder paste (6) in the pattern Q2 hole is melted and supplied to the required locations of the wiring pattern (la) on the circuit board (1), and is deposited as preliminary solder. According to the method of the above embodiment, Like conventional.

Screen film thickness 1 There is no need to set conditions that take into account various printing conditions such as misalignment and printing smearing, and it is only necessary to efficiently fill the fine patterns (2) and holes with solder paste (6). Printing methods can be used. In addition, in cases where the ratio between the thickness of the supply plate 0υ and the hole diameter is extremely large, it is sufficient to print the solder paste (6) several times repeatedly and fill it in the pattern (6) holes one after another. It is even more effective when used in combination with other methods. Furthermore, if a transparent glass plate is used for the supply plate αυ, even more accurate positioning can be achieved and the yield can be further improved.

When the supply plate αD is used, it can be cleaned as necessary and used repeatedly.

By changing the thickness of the supply plate αD, the amount of solder supplied can be adjusted to an appropriate amount. In addition, the pattern (2) of the supply plate αD can be formed finely by laser processing, etc., and even if the pattern holes are minute, the solder paste (2) can be formed by heating.
6) is melted and dropped, so fill it in the hole and create a trench.
There is no residual solder, and the amount of printed solder is uniform, allowing for precise printing and feeding.

In the above embodiment, a transparent glass plate was used as the supply plate Qυ, but it can be used as long as it can withstand the solder melting temperature.

Other transparent materials may be used, or the holes in the pattern (2) of the supply plate αυ may be made of other transparent materials. In some cases, the shape of the solder may be made wider at the bottom to improve solder flow.

Furthermore, the solder may be supplied to parts that require low precision by the conventional screen printing method, and only the parts which require precision may be supplied with solder by the supply plate.

In addition, the fine parts of the circuit board are covered with a suitable means, pre-soldered by immersion in solder, and after this, the cover of the fine parts is removed and solder is supplied only to these parts using the supply plate. Good too.

Furthermore, the patterns α of the supply plate Ql) have the same shape.

It doesn't have to be the same size, and there is no problem even if you mix appropriate shapes and sizes depending on the electrodes of the parts to be mounted.

For example, there may be a pattern with a diameter of 50 μm and a pattern with a square size of 3 to 5 mm. In this case, the solder supply thickness (wet thickness) is affected by the shear rate due to the difference in hole dimensions in the conventional screen printing described above. However, with the means of this invention, the thickness can be made uniform.

Furthermore, it is possible to place a plurality of supply plates 0D side by side on one circuit board (1) and supply solder to the circuit board (1). For example, by filling the same or different supply plates with pastes with different solder components corresponding to the electrode materials of the mounted components, preliminary solder can be supplied, further improving the reliability of component joining such as hybrids. .

Further, by using a plurality of supply plates whose thicknesses are changed depending on the weight, size, etc. of the mounted components, the amount of supplied solder can be optimized and highly reliable mounting can be achieved.

Furthermore, it can also be applied to the case of replacing mounted components. That is, when replacing a workpiece such as a flip wig by supplying solder, accurate fine solder can be easily supplied even if there are other parts to be attached. At this time, even if the wiring conductor on the circuit board is only the metallized base,
Preliminary solder can be supplied even if a thin layer of previous solder remains.

Therefore, the method of the present invention can be widely applied to a circuit board that has been pre-soldered using the above-mentioned conventional method, such as when the solder is made thicker in a specific part.

〔Effect of the invention〕

As described above, according to the method of the present invention, a solder supply pattern is formed on a supply plate, the holes in this pattern are filled with solder paste, the solder paste is placed on a circuit board, and the supply plate is heated to melt the solder paste. death.

Since it is supplied onto the circuit board, a uniform amount of pre-solder can be applied to the seminal vesicles in a fine pattern.

In addition, the amount of solder supplied can be made appropriate regardless of the size of the pattern, and the reliability of mounting is improved.

[Brief explanation of drawings]

1 and 2 are a perspective view and a vertical sectional view of a screen printing section showing a conventional preliminary solder supply method, and FIG. 3 is a supply plate and a circuit board showing a preliminary solder supply method according to an embodiment of the present invention. FIG. 1... Circuit board, 6... Solder paste, 11...
- Supply plate, 12...pattern Note that the same reference numerals in the drawings indicate the same or equivalent parts. 114 Figure 2; Figure 3 Procedural Amendment (Voluntary) 1. Indication of the case Japanese Patent Application No. 59-46456 2. Invention (
7) Title Method for supplying preliminary solder to circuit boards 3, Person making the amendment Representative Hitoshi Katayama Department 4, Agent 5, ``Detailed description of the invention'' column of the specification to be amended. 6. Delete "supply solder" on page 10, line 12 of the specification of amendments. that's all

Claims (6)

[Claims] (1) Fill the solder supply hole drilled in the supply plate with solder paste, align and place the supply plate on the circuit board, and melt the solder paste during heating to connect the circuit board. A method of preliminarily supplying solder to a circuit board. (2) The method for preliminarily supplying solder to a circuit board according to claim 1, wherein the supply plate is a transparent glass plate. (3) Place multiple supply plates side by side on the circuit board. A preliminary solder supply method to a circuit board according to claim 1 or 2, which supplies solder. (4) The method for preliminarily supplying solder to a circuit board according to claim 3, wherein the thickness of each supply plate is varied. (5) A preliminary solder supply method to a circuit board according to claim 3 or 4, characterized in that each supply plate is filled with a solder paste of a required composition. (6) Preliminary solder supply to a circuit board according to any one of claims 1 to 6, in which solder is further supplied by a supply plate onto a circuit board to which solder is partially attached. method