Frequently Asked Questions about PCB

Almost every link and step in the PCB manufacturing process may have a variety of problems. Now we share some common bad phenomena of PCB as follows, hoping to learn from each other and make progress together.

1. The lack of process edge or the unreasonable design of process edge leads to the equipment cannot mount normally.

2. The equipment cannot be accurately and firmly positioned due to a lack of positioning holes or incorrect positioning holes.

3. Poor drilling phenomena such as hole shortage, hole deviation, hole collapse, and multiple holes directly lead to an open circuit of the line or missed drilling.

4. Lack of Mark points or nonstandard design of Mark points causes difficulty in machine identification.

5. The designator or polarity mark is missing, the designator is reversed, the silkscreen or solder mask is on the pad and test point, and the characters are too large or too small.

6. The design of the test point location is unreasonable: the test point is too small, and the test point is placed below the component or too close to the component.

7. The distance between the pad and the via is too close or there is a via on the pad, which causes the solder to melt and flow to the bottom of the PCB during furnace welding, resulting in the defect of less tin in solder joints.

8. Unreasonablesize design of the pad may lead to faulty soldering, displacement, tombstoning, short circuit of the welding bridge, and other undesirable phenomena during welding.

9. The distance between components is not standardized, and the maintainability is poor.

Sufficient distance must be ensured between the patch pieces. Generally, the minimum distance between the reflow soldering patch pieces is 0.5mm, the minimum distance between the wave soldering patch pieces is 0.8mm, and the distance between the high device pieces and the rear patch pieces should be larger. No patch piece is allowed within 3mm around BGA and other devices.