Maybe you should understand about Pad Type before PCB design
2019-11-20 14:45Writer: qyadminReading:
Before engaging in the precise details, it's important to comprehend the pros, negatives, and unknowns regarding the two most common types of solder pads, solder-mask-defined (SMD) and non-solder-mask-defined (NSMD) pads.
Industry reliability studies have revealed that NSMD-type pads are strongly suggested for some 0.5mm pitch PCB designs. They have the benefit of tighter copper sizes, in comparison to solder mask measurements, and the standard coverage is way better at the solder melting temperature. The pads are also smaller, enabling improved routing. Another benefit of the NSMD pad is reduced stress focused on the solder joint, which raises solder joint reliability particularly if paste overprinting can be used.
Solder-Mask-Defined (SMD) and Non-Solder-Mask-Defined (NSMD) Pads
However, there are a few companies that swear by SMD pads claiming that the higher copper area (of the pad) and the solder-mask overlap create better adhesion power to the fiber/cup laminate. They declare that flexing and bending during accelerated thermal biking screening causes a poor link where in fact the pad connects to the PCB and may be the primary failure location, instead of the normal solder fracture which dominates the NSMD pad.
Be certain and speak to your PCB fabricator as well as your PCB assembly merchant and discuss their encounters and preferences before making a decision which kind of pad will be utilized on your PCB design.