Lead-free product PCB pad design rules

- Aug 19, 2019-

1.Pcb board heat distribution design problem

In order to reduce the △T of the PCB surface during the soldering process, the heat dissipation design should be carefully considered, such as uniform component distribution, copper foil distribution, and optimized PCB layout to minimize the ΔT on the printed board.


2. Elliptical pcb pads can reduce copper exposure after soldering pads

3. Transition stage BGA, CSP adopt SMD pad design to facilitate exhaust and reduce "holes".

The pad design of BGA and CSP is divided into two types according to the solder mask method: SMD and NSMD.


4.For lead-free wave soldering pads for transitional via components, and double-sided soldering (A-side reflow soldering, B-side wave soldering), SMD pad design can also be used for the A-side large components and via-hole components wave soldering pad. Which can reduces solder bumping and pad peeling phenomenon.


5. The aperture of the through-hole component insertion hole needs to be appropriately increased to increase the filling height of the solder in the insertion hole.


6. In order to reduce the porosity, the vias on the BGA and CSP pads should be blind-holed and required to be flush with the pad surface.



7. Promoting environmentally friendly design. Since WEEE is an instruction on the recycling and reuse of waste electrical and electronic equipment, 60%~70% of the weight must be recycled. At the same time, the principle of who manufactures should recycle themselves as specified. Therefore, in designing, it is necessary to take into account the cost of recycling and recycling WEEE when select materials. The choice of technics materials, PCB materials, components and other components according to the environmental conditions and service life of the product design, including the choice of pcb assembly method and pcb manufacturing technics process design. Excessive selection of high quality, long life, high reliability parts and materials will not only increase the manufacturing cost of the product, but also increase the cost of recycling and recycling of waste electrical and electronic equipment.



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