JPH0272694A - Soldering method - Google Patents

Abstract

PURPOSE:To prevent the occurrence of short circuits of solders by printing neighboring solder pastes on foot-print patterns which are aligned and formed on a printed board in a zigzag pattern, and performing soldering. CONSTITUTION:A plurality of rectangular foot-print patterns 2 are aligned and formed at an equal interval on a printed board 1. About one half of the length of each solder paste pattern 3 covers about one half of the length of the foot-print pattern 2. The neighboring patterns 3 in the alignment cover the patterns 2 in this way in a zigzag state. Therefore, there is no narrow facing surfaces between the solder paste patterns 3. The entire solder paste patterns 3 are heated with steam and fused. At this time, the solder moves in the direction where the solder paste patterns 3 are not printed and soldering is performed. The extrusion of the solder into the lateral direction is less. Thus the short circuits between the neighboring patterns can be prevented.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a soldering method in which solder paste is printed in a zigzag pattern in the longitudinal direction of a rectangle of a plurality of aligned foot patterns, and a soldering method that can prevent short circuits caused by soldering. A rectangular footprint pattern is formed on a plurality of rectangular footprint patterns arranged at equal intervals on a printed circuit board in correspondence with a plurality of terminals of components mounted on the printed circuit board. An elliptical solder paste having a major axis approximately equal to the length of the pattern and a minor axis approximately approximately equal to the width of the rectangular pattern is used. The footprint pattern is printed in a zigzag pattern, and a chip component is placed on the printed footprint pattern with solder paste and soldered in a steam atmosphere.

[Industrial application field]

The present invention relates to a soldering method when, for example, a quad flat package is mounted on a printed circuit board, and particularly relates to a soldering method in which solder paste is printed in a zigzag manner in the longitudinal direction of a rectangle of a plurality of aligned fund patterns. be.

When mounting an electronic component 5 having a large number of terminals, such as a mulberry or Tofura Sotopano Cage (hereinafter referred to as QFP) on a printed circuit board, solder paste is printed on a large number of rectangular footprint patterns formed on the printed circuit board. The solder is soldered by placing a Q F l) on the solder and heating it with steam, but since the pattern spacing is narrow, solder shorts are likely to occur and it takes a lot of man-hours to correct them, so a horn method to prevent solder shorts is desirable. It is rare.

[Conventional technology]

The conventional method will be explained below with reference to FIGS. 3 and 4. The same reference numerals indicate the same objects throughout the figures.

As shown in FIG. 3, when a QFP 4 is mounted on a printed circuit board 1, a plurality of terminals 40 on the outer periphery of the QFP 4 are soldered in accordance with a footprint pattern 2 formed on a printed circuit board 1. . Details will be explained below.

As shown in FIG. 4 (ta), a plurality of rectangular footprint patterns 2 are formed on the printed circuit board 1 side by side in the XX direction, aligned at a pitch of, for example, 0.65 m1 or less.

As shown in FIG. 4(b) (an enlarged view of a portion A surrounded by a one-dot chain line in fal), a solder paste pattern 3a is printed over the entire surface of the footprint pattern 2. Therefore, the solder paste pattern 3a has the same shape as the footprint pattern 2.

Therefore, the QFP 4 is placed with its terminal aligned with the footprint pattern 2, and heated in a steam atmosphere to melt the solder paste pattern 3a and perform soldering.

[Problem to be solved by the invention]

According to the above conventional method, if solder paste is printed on the entire surface of the printed pattern and soldered as explained in FIG. longitudinal direction,
Since the solder paste is printed in the X direction in the second pattern +a), the distance between adjacent solder paste patterns becomes even narrower, resulting in a large number of solder sheets. Therefore, there is a problem that correction work for solder short circuits is required, which takes a lot of man-hours.

An object of the present invention is to provide a method for soldering a QFP that can prevent short circuits caused by soldering.

[Means to solve the problem]

FIG. 1 is a block diagram showing an embodiment of the present invention.

In the figure, 1 is a printed circuit board, 2 is a plurality of rectangular footprint patterns formed on the printed circuit board 1 at equal intervals, and 3 is a footprint pattern 2 whose length is almost the same as that of the footprint pattern 2. This is a solder paste pattern printed so as to cover approximately half of the length of the footprint pattern 2 in a zigzag pattern adjacent to each other in the array.

Therefore, the mounting components are placed on the footprint pattern 2 on which the solder paste pattern 3 is printed and soldered in a brown atmosphere.

(Function) Since the solder paste patterns 3 adjacent to each other in the footprint pattern 2 are printed in a zigzag pattern with a difference of approximately half the length from each other, there is no narrow opposing surface between the solder paste patterns 3, and the solder paste patterns 3 are heated by the tea. When all of the solder paste pattern 3 is melted, the solder moves toward the part where the solder paste pattern 3 is not printed and is soldered, so that there is little solder overflowing in the lateral direction and the solder paste pattern 3 is not printed on the solder paste pattern 3. It can be prevented.

Therefore, the number of man-hours required for repairing solder shorts can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows an embodiment in which the present invention is applied to a footprint pattern 2 formed on a printed circuit board 1 explained in FIG.

As shown in the figure, a solder paste pattern 3 is placed in a zigzag pattern on a plurality of aligned rectangular footprint patterns 2.
is printed. That is, an elliptical solder paste pattern 3 having a long axis approximately close to the length of the footprint pattern 2 and a short axis approximately close to the width of the footprint pattern 2, with approximately half the length of the solder paste pattern 3 The prints are printed in a zigzag pattern, alternating each other about half of the length.

With this configuration, as shown in Figure 3,
Align terminal 40 on footprint pattern 2 and connect QF
When P4 is placed and heated in a steam atmosphere, there is no narrow opposing surface between the solder paste patterns 3, and when the solder paste patterns 3 are melted, the solder paste pattern 3 of the footprint pattern 2 is not printed. Soldering is carried out by moving in the direction of the part, and there is little solder protruding in the lateral direction.

Therefore, short circuits between adjacent circuit boards can be prevented, and the number of man-hours required to correct solder short circuits can be reduced.

In the above example, the solder paste pattern 3 is elliptical, but as shown in FIG. 2, it may be a rectangular solder paste pattern 3b that is approximately the same size as the footprint pattern 2.

〔Effect of the invention〕

As explained above, according to the present invention, by printing solder paste in a zigzag pattern next to each other on footprint patterns formed in alignment on a printed circuit board and soldering, solder shorts between footprint patterns can be prevented. This has the effect of being able to prevent this from occurring and reducing the number of man-hours required for correction work.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, a perspective view, FIG. 4 is an explanatory diagram of a conventional example. In the figure, 1 is a printed circuit board, 2 is the footprint pattern, 3.3a is a solder paste pattern, 4 indicates QFP. electric

Claims (1)

[Claims] A plurality of rectangular footprint patterns (2) arranged at equal intervals on the printed circuit board (1) correspond to a plurality of terminals of components mounted on the printed circuit board (1). )
A solder paste pattern (3) having a length substantially similar to the length of the footprint pattern (2) and a width substantially similar to the width of the footprint pattern (2) is placed on top of the footprint pattern (2). Almost half of the length of the solder paste pattern (3) is printed so that approximately half of the solder paste pattern (3) covers the footprint pattern (2) next to each other in a zigzag pattern, and the solder paste pattern (3) is printed on the foot. A soldering method characterized by placing mounting components on a printed pattern (2) and soldering in a steam atmosphere.