Analysis of Common Defective Phenomena In PCB Assembly

In the process of PCB Assembly and Manufacturing, some errors in operation may lead to poor SMT Assembly phenomenon. So, which defective phenomena will occur in PCB Assembly?

Common Defective Phenomena In PCB Assembly

1. Stand Up
Causes: Uneven tension on both sides of copper and platinum; Too fast preheating heating rate; Machine placement offset; Uneven thickness of solder paste printing; Uneven temperature distribution in the reflow oven; Solder paste printing offset; The machine track splint is not tight, resulting in placement offset, etc.

2. Short Circuit
Causes: Too large distance between stencil and PCB board leads to too thick solder paste printing and short circuit; Component mounting height is set too low to squeeze solder paste and lead to short circuit; Reflow oven heats up too fast, resulting in short circuit; Component placement offset lead to short circuit; Poor stencil opening (too thick thickness, too long pin opening, too large opening) lead to short circuit, etc.

3. Component Shifted
Causes: The positioning reference point on the circuit board is not clear; The positioning reference point on the circuit board is not aligned with the reference point of the stencil; The fixed clamping of the circuit board in the printing machine is loose, and the positioning thimble is not in place, etc.

4. Component Missed
Causes: The vacuum pump carbon sheet is not good enough to cause the lack of parts; The suction nozzle is blocked or the suction nozzle is bad; The thickness of the component is improperly detected or the detector is bad; The mounting height is improperly set, etc.

5. Solder Skip/ Solder Empty
Causes: Weak solder paste activity; Poor stencil opening; too large copper-platinum spacing or large copper paste small components; Too much pressure on the scraper; Poor flatness of component feet (lifting feet, deformation) The hot zone heats up too fast, etc.



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1)Strength Guarantee

▪ SMT factory: With imported SMT machines and multiple optical inspection equipment, which is able to produce 4 million points per day. Each process is equipped with QC personnel who will keep an eye on product quality.

▪ DIP production line: Two wave soldering machines and more than 10 employees who have worked for over three years. That’ s to say, these workers are highly skilled and can weld various SMT & DIP components.

2)Quality Assurance With High Cost Performance

▪ High-end equipment can paste precision special-shaped parts, BGA, QFN, 0201 package. It can also be soldered prototype pcba via SMT machine and placing bulk materials by hand.

▪ Both samples, small and large batches can be produced. And there is no SMT Machine starting cost.

3)Rich Electronic Products SMT Soldering Experience With Stable Delivery

▪ Accumulated services to thousands of electronics companies, involving SMT soldering services for various types of automotive equipment and industrial control motherboards. Furthermore,PCBA Products are often exported to Europe and the United States, and the quality is able to be affirmed by new and regular customers.

4)Strong Maintenance Ability & Reliable After-Sales Service

▪ The maintenance engineers have sophisticated experience so that those defective boards caused by all kinds of smt soldering can be repaired. Meanwhile, ensuring the connectivity rate of each circuit board also make sense.

▪Order problems feedback will get response, solution and solved as soon as possible.


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