JPH06204652A - Printed circuit board - Google Patents

Abstract

PURPOSE:To decrease solder bridges and unsoldered components of the electrodes and the pads of an SMT component, by providing dummy pads in the vicinity of the direction of solder dipping of the pads of the SMT component. CONSTITUTION:Concerning to a printed circuit board 1, an SMT component 11, the pads 2 and the dummy pads 3 of the SMT component 11, and the electrodes 4 of the SMT component 11 are connected with jet solder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pad structure of a printed circuit board used for electronic information related equipment and the like.

[0002]

2. Description of the Related Art A conventional printed circuit board on which an SMT component is mounted has a structure corresponding to an electrode of the SMT component and having a solder connection pad electrically connected to a signal pattern as shown in FIG. there were. FIG. 3 shows a printed circuit board 1.
FIG. 4 is a sectional view showing a passing state of a solder dip tank. Figure 3
As the printed circuit board 1 moves in the direction of the arrow as shown in FIG. 5, SMT components such as the transistor 11 and the chip resistor array 13 enter the flow of the jet solder 15, and the solder touches the pads 2 and the electrodes 4, and The solder that has adhered to remains and remains electrically connected. However, this jet solder 1
The flow of the jet solder 15 when the SMT component and the pad enter the flow of No. 5 changes due to the deterioration of the viscosity and the adhesiveness due to the temperature of the solder and the secular change. The state of the vortex of the flow of solder changes, and the state of adhesion of solder to the pads 2 and the electrodes 4 changes. Therefore, problems such as unsolder to which solder does not adhere and solder bridges where solder is excessively attached to a plurality of pads or electrodes occur. Therefore,
A method of passing through a solder dip bath for soldering was considered.

[0003]

However, the above method of passing through the solder dip tank has a problem that the solder of the electrode and the pad of the SMT component becomes unsoldered or a solder bridge is formed between adjacent electrodes. Was there.

Therefore, in order to prevent unsoldered solder and solder bridges, the flux and the solder material are selected for each type of substrate, and the mounting conditions such as the temperature condition of the solder dip bath and the time for passing through the solder dip bath are set. I had to find the optimum value. Further, depending on the case, it is necessary to redesign the pattern where the solder becomes unsoldered due to the positional relationship between the adjacent components or the solder bridge occurs.

The present invention solves these problems.
The purpose is to reduce unsolder and solder bridge between the electrode of the SMT component and the signal pad of the printed circuit board by forming a dummy pad near the rearmost pad in the solder dip direction of the SMT component.

[0006]

In order to solve the above-mentioned problems, the printed circuit board of the present invention is characterized in that a dummy pad is formed in the vicinity of the pad of the SMT component to be soldered by the solder dip bath. To do.

[0007]

1 is a perspective view showing the structure of a printed circuit board according to an embodiment of the present invention.

In the printed circuit board 1 of this embodiment,
As shown in FIG. 1, SMT components 11, 12, 13, 14
The dummy pad 3 is formed in the vicinity of the rearmost electrode 4 in the solder dip direction and the pad 2 forming a pair therewith.

As shown in FIG. 3, the printed circuit board 1 moves in the direction of the arrow, and the transistor 1 is inserted into the jet solder 15.
When an SMT component such as 1 or the chip resistor array 13 is inserted, the force of the solder attaching to the dummy pad 3 changes the vortex state of the jet solder 15, and the pad 2 and the electrode 4
When the printed circuit board moves and the SMT component is about to come out of the flow of the jet solder 15, the solder is attracted to the dummy pad 3 side due to its own viscosity, and the solder bridge is formed. To be prevented. Further, even if the adhesiveness or viscosity of the solder changes due to the temperature of the solder bath, the temperature of the pad or the SMT component and its electrode 4, the deterioration due to aging or fatigue, the provision of the above-mentioned dummy pad 3 ensures more reliability. In addition, unsolder and solder bridge are reduced.

Therefore, the selection of flux and solder material,
Finding the optimum value of the mounting conditions such as the time to pass through the solder dip bath, and re-designing the pattern where unsoldered solder bridges occur due to the positional relationship of adjacent components It is possible to reduce problems such as unsoldered solder and solder bridges without taking any measures.

[0011]

As described above, the dummy pad is formed in the vicinity of the pad on the rear side in the solder dip direction of the SMT component, so that the adhesion and the viscosity of the solder can be improved and applied to the electrode and the printed circuit of the SMT component. It is possible to provide a printed circuit board having an effect of reducing unsoldered signal pads on the board and solder bridges.

[Brief description of drawings]

FIG. 1 is a perspective view showing the structure of an embodiment of the present invention.

FIG. 2 is a perspective view showing a structure of a conventional example.

FIG. 3 is a cross-sectional view showing a printed circuit board passing through a solder dip bath.

[Explanation of symbols]

 1 Printed Circuit Board 2 Pad 3 Dummy Pad 4 Electrode of SMT Component 11 Transistor 12 Chip Resistor 13 Chip Resistor Array 1 14 Chip Resistor Array 2 15 Jet Solder (Flow Solder)

Claims (1)

[Claims] 1. A SMT soldered in a solder dip bath in a printed circuit board used in electronic equipment.
A printed circuit board having a dummy pad formed in the vicinity of a pad of a component.