JPH04129294A - Supplying method for solder - Google Patents

Abstract

PURPOSE:To easily and inexpensively supply solder of two types or more of thicknesses without restricting wirings on a board by supplying solder of a thickness B on the board by a second screen plate, and supplying solder of a thickness A to a region corresponding to the opening of the board by a first screen plate superposed on the second plate. CONSTITUTION:A superposed screen plate 5 is so placed as to be brought into direct contact with a board 3, and the upper surface of the plate is lightened. Then, since a part in which the parts immersed with solder pastes of upper and lower screen plates are superposed, is finer than a mesh structure of the upper plate 1 in the mesh structure of the lower plate 5, solder paste 2 immersed to the plate 1 is not immersed to the board 3 through the plate 5. As a result, only the paste 6 of the plate 5 is printed on the board 3. On the other hand, the paste 3 of the plate 1 on the opening 8 of the plate 5 is printed on the board 3 through the opening. Thus, two types of thicknesses of the solders 4, 7 are printed on the board 3.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for completely supplying solder of at least two different thicknesses onto the same substrate.

<Prior art> Conventionally, parts having terminals with a narrow pitch of 0.5000 pitches or less, QF P (quad flat pac
kage) or T A B (tape auto
The solder film thickness required for soldering and mounting on a board is different between (mated bonding) and peripheral chip components (resistors, capacitors, etc.).

In other words, QFP and TAB require a small amount of soldering due to the narrow pitch between the terminals, while chip components, on the other hand,
A large amount of solder is required to support the parts.

FIG. 5 shows the wiring pattern of the board.

It is the bonding part of AuQFP or TAB, and B
The mounting of chip parts is a part. In addition, C is a plating lead for electrolytic plating, which will be described later, and D is a wiring board on both sides of the board.
A through hole for carrying out IA, E is the outer periphery of the substrate.

FIG. 6 shows an example of supplying solder to the above board.

For bonding part A' of QFP or TAB (requiring a small amount of solder), electricity is connected to bonding part A' through a solder lead C, and solder with a film thickness of about 20 μm is supplied using the electrolytic plating method, in which solder is plated. For part B' (requiring a large amount of solder), solder paste is transferred to the board via Nuclean, and the film thickness is 2.
About 00μrrLt of solder was supplied.

<Problems to be Solved by the Invention> According to the conventional solder supply method, solder plating is performed by electrolytic plating method, so it is necessary to wire plating leads for flowing electricity to the bonding part, which makes it difficult to design the pattern of the board. There were restrictions.

In other words, since the plating leads form a film after plating, holes, etc. are required, and single-sided wiring cannot be achieved.

Furthermore, the number of blank wires increases due to the blind lead wiring, resulting in an unnecessarily narrow pitch, or conversely, it becomes necessary to increase the size of the board itself.

Furthermore, partial solder plating is expensive and causes a relatively high unit price of the board.

In order to solve all of these problems, it may be possible to stop partial solder plating and perform screen printing several times depending on the type of solder film thickness. This could not be said to be an effective method as it caused deterioration of the attached clean version.

In view of the above-mentioned problems, the present invention provides a method of supplying solder having two or more film thicknesses easily and at low cost without causing any noise in the wiring on a substrate.

Means to solve problems〉 The present invention provides at least two types (A) on the same substrate.

In the method of supplying solder having a film thickness of B), the first method has a mesh structure of a predetermined size and supplies solder having a film thickness of A.
and a second screen plate which has a mesh structure that is thinner than the mesh structure of the first 7-clean plate, and which supplies solder with a film thickness of B and has an opening in a part thereof. and the superimposed screen plate to the second screen plate.
Solder is printed on the substrate by bringing the screen plate into contact with the substrate so as to directly face the substrate.

<Operation> According to the present invention, solder having a film thickness of B is supplied onto the substrate from the second screen plate that directly faces and contacts the substrate, and the solder is supplied to the substrate through the opening provided in the second screen plate. A first screen plate superimposed on the second screen plate supplies solder having a film thickness of A to a region of the substrate corresponding to the opening.

<Example> An example of the present invention will be described below with reference to the drawings.

Figure 1 shows the wiring pattern of the board (those explained in the prior art are given the same symbols) A is QFP
Alternatively, B is the bonding part of TAB, and B is the mounting part of the chip component. ◎ Figure 2 shows an example of supplying solder to the above board.

Solder is supplied to both A', which requires a solder film thickness of 40 .mu.rrtt, and B', which requires a solder film thickness of 200 .mu.mt, by the Nuclean printing method.

3 and 4 show a cross-sectional view of the screen plate and an example of supplying solder to the board.

FIG. 3 <a> shows the case of solder paste printing using one screen plate for forming a total film thickness of 200 μrrLt.

Reference numeral 1 is a printing screen plate having a mesh structure of a predetermined size, and 2 is a portion soaked with solder paste.The solder paste is soaked in corresponding to the parts of the board that require soldering.

When this screen plate 1 is placed on the substrate 3 and the screen plate 1 is lightly rubbed from above and removed from the substrate 3, the solder paste 2 oozes out from the screen plate 1, and a solder paste 4 having a film thickness of 200 μst is printed on the substrate 8.

Note that in the electrolytic plating method, the solder amount and the solder film thickness are not the same, but in the solder paste screen printing method, the solder film thickness is approximately H with the same amount of solder as in the plating method.

FIG. 3(b) shows the case where solder paste is printed using a screen plate that creates a 40 μmtO film thickness.

Similarly to FIG. 3(a), 5 is a printing screen plate with a mesh structure of a predetermined size, and 6 is a basic lean plate 1. The difference from 1 is that firstly, the solder on the substrate 3 does not require a 40 μm tO film thickness. The point is that an opening 8 is provided in a portion corresponding to the attachment location.

Therefore, when the screen plate 5 is placed on the substrate 8 and solder paste is printed, the solder paste 7 with a film thickness of 40 μmt is supplied to the substrate 8, but the solder is not supplied to the portion of the substrate 8 corresponding to the opening 8.

A second difference is that the mesh structure of the screen plate 5 is thinner than that of the screen plate 1, and has a characteristic that allows the solder paste (2t) impregnated into the screen plate 1 to pass through.

FIG. 4(b) shows how such screen plates 1.5 are stacked one on top of the other as shown in FIG. 4(a), and solder printing is performed using the stacked screen plates.

The screen plate 5 directly connects the superposed screen plate to the substrate 3.
Place it on the substrate 3 so that it is in contact with the plate, and lightly rub the entire surface of the plate. Then, in the area where the solder paste soaked parts of the upper and lower screen plates overlap, the mesh structure of the lower screen plate 5 is thinner than the mesh structure of the upper screen plate 1, so the solder paste soaked into the screen plate 1 overlaps. 2 cannot pass through the screen plate 5 and seep out onto the substrate 3, and as a result, only the solder bases 1 to 6 of the lower screen plate 5 are printed on the substrate 3.

- 10,000, the solder paste 2 of the screen plate 1 on the opening 8 of the lower screen plate 5 passes through the opening to the substrate 3.
printed on top.

In this way, the substrate 3 has 40 μmt and 200 μmt.
Two film thicknesses of half EE 4.7 are printed.

According to this method, by printing one screen plate, two
Solder can be supplied with various film thicknesses.

In addition, since the upper screen plate 1 does not have an opening, it will not get caught when rubbing the screen plate, and it is possible to prevent the screen plate from deteriorating.

In this project example, solder supply with two types of film thickness was explained.
It goes without saying that the present invention can also be applied to supplying solder with eight or more film thicknesses.

<Effects of the Invention> According to the method of the present invention, -
Since it is possible to supply solder with two or more film thicknesses by multiple screen printing, there are no restrictions on the wiring pattern on the board, the processing procedure is simplified, and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a wiring pattern of a board according to the method of the present invention;
Figure 2 is a diagram showing an example of supplying solder to a board using the method of the present invention, Figures 8 and 4 are diagrams explaining solder printing on a board using a printing screen plate, and Figure 5 is a diagram showing an example of supplying solder to a board using the conventional method. A diagram showing a wiring pattern, and FIG. 6 is a diagram showing an example of supplying solder to a board using a conventional method. 1.5... Screen plate, 2.6... Solder paste, 8... Board, 4.7... Solder, 8...
Aperture. Figure - Lower layer 11111 3111 JII4111 1111111 *5 6m in Figure 1

Claims (1)

[Claims] 1. A method for supplying solder having at least two types (A, B) of film thickness on the same substrate, comprising: a first screen plate having a mesh structure of a predetermined size and supplying solder having a film thickness A; A second screen plate which has a mesh structure thinner than that of the first screen plate and which has openings in a part and which supplies solder with a film thickness B is superimposed on the second screen plate, and the superposed screen A plate is brought into contact with the substrate so that the second screen plate directly faces the substrate, and solder having a film thickness of B is supplied from the second screen plate and passes through the opening of the second screen plate. A solder supply method characterized by supplying solder having a film thickness of A from the first screen plate.