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What are the effects of PCB on PCBA processing quality?

What are the effects of PCB on PCBA processing quality?

1. Discussion on PCBA technology
PCBA manufacturing and processing is a very complicated process. The entire PCBA processing seems to be only one word different from PCB. In fact, the poor process varies greatly. PCBA has a series of back-end processes on the PCB, such as solder paste printing, SPI inspection SMT processing, reflow soldering, DIP plug-in soldering, wave soldering / selective wave soldering, PCBA first-piece inspection, etc. These processes are PCB does not come with.

However, because all the following processes are sent to the PCB board, the quality of the PCB determines the quality of the entire PCBA. So what aspects of the PCB have an impact on the PCBA? Today, the editor of Jingbang Electronics will share with you.

First, the board is dirty

Dirty board surface is mainly caused by high flux solid content, too much coating, preheating temperature is too high or too low, or because the conveyor belt PCB clamping claw is too dirty, too much oxide and tin slag in the solder bath, etc. .

The main solution is to choose the appropriate flux; control the flux coating amount; control the preheating temperature; check the cleaning effect of the automatic cleaning PCB clamping claws and take measures; timely clean up the oxide and tin slag on the surface of the solder bath.

PCBA_and_PCB_board

Second, the white line left

White residue is commonly known as hoarfrost. Although it does not affect the surface insulation resistance, the customer does not accept it.

Solution: first use the flux and then the solvent to clean it; if it cannot be cleaned, it may be due to the expired aging of the flux, or it may be exposed to the air to absorb water vapor, or it may be due to the excessive moisture content in the cleaning agent (solvent), or the flux Does not match the cleaning agent, the supplier should be asked to help resolve or replace the flux, cleaning agent.

Third, PCB deformation

PCB deformation is mainly caused by large quality PCBs or uneven component layout

When designing the PCB, try to make the components evenly distributed, and design a support belt in the middle of the large-sized PCB (design the non-layout component area with a width of 2 to 3mm); or use a mass-balanced tool to press the sparse components on the PCB and realize it during welding Mass balance.

2月-03-2020

FASTPCBA