|
How to do well in Assembly?
Date:2016-08-01
In PCB Assembly, there is a set of processthat is constantly being followed. One process cannot be skipped; one cannot beswitched to be performed over the other. For an SMT component populated PCB, itis always going to be the following processes (arranged in order):
Solder paste printing
Automatic placement
Reflow
But even if the processes are followed,certain problems arise when a populated PCB is inspected. In here, we are goingto tackle some of the PCB Assembly problems that are commonly encountered anddiscuss how to solve and prevent from happening again:
Solder bridging
Solder bridging is a phenomenon where atleast two neighbouring component pins have short circuited by way of anunnecessary solder. This phenomenon may be due to the following: excess soldervolume, inaccurate placement of the machine, or the plain mismatch of the PCBfootprint. To solve this problem, the engineers or assemblers should do thefollowing: reduce the solder volume by changing the printing machine settingsor go far as changing stencil mask opening.
2. Coplanarity
Coplanarity is a PCB Assembly problem thatcan be solved easily. This is mainly caused by a physically damaged component.But the cause of the damage will be difficult to find. It may be due to thedamage coming from the component supplier or a damage induced by the automaticplacement machine during the pick and place process. Either way, the focus ofthe investigation should only be concentrated on the component itself.
3. De-wetting
De-wetting is a solder anomaly wherein thecomponent pins don’t have enough solder creeping (wetting) around it. Itis also a common PCB Assembly problem. This may be caused by thefollowing: insufficient solder volume or mismatch of PCB footprint against thecomponent. To solve this problem, the engineer and/or the assembler must do thefollowing: change the solder volume deposit by changing the solder pasteprinting machine setting or change the stencil mask opening or change the PCBfootprint itself so it will match with component pins.
Special |
About us |
Prodcuts List |
Our Capability |
Factory Tour |
Information |
Contact us |
News |
How to do well in Assembly? |
2016-08-01 |
Notice when you design the Multilayer PCBs |
2016-05-26 |
Our Location | ||||||
|