Back when I was in school, I spent a lot of time working on my car. I could not afford a new one, and I avoided putting it in the shop whenever I could. One of the repair jobs that I enjoyed most was working on the exhaust system, because it gave me an opportunity to do some welding. Although it was a hot job, I relished trying to make the smoothest joint that I could. A secure connection and a smooth joint usually translated into a good quality weld.pcb design price
Welding is a lot like soldering components on a circuit board in that there are tell-tale signs that indicate a good solder joint. For example, a good solder joint will have solder applied to both elements being joined, and there will be no air pockets. The importance of having good solder joints to PCB quality control is well-known, as bad joints can lead to unreliable signal transfer or tombstoning and no signal flow at all. Let’s examine what is meant by good SMT solder joint quality and then take a look at some PCB assembly testing methods your contract manufacturer (CM) can employ to ensure your board exhibits it.
In the figure above, an example of a PCB with several types of components mounted is shown. In each case, a good solder joint has been established, which means that the component is securely attached to the board, and:
component pin and footprint pad are aligned;
pad area is completely covered with solder;
component pin area in contact with pad is completely covered with solder;
no excess solder covers component;
solder joint is smooth;
solder joint does not contain voids; and
solder does not cover solder mask.
The list above are indications that your design’s surface mount device (SMD) has been soldered well; however, it is not exhaustive, as traces that run within or through your board, better known as vias, cannot be completed examined from the board’s exterior. For this, you must rely on the quality of your CM’s printed circuit board assembly process.