PCB Design Glossary

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A land or pad is a conductive part of a printed circuit board that is meant to connect to the pin of an integrated circuit.  



Light Emitting Diode.  These are devices that convert electrical energy into light.


Pure substances undergo phase changes at specific temperatures.  Mixtures undergo phase changes over a range of temperatures.  Liquidus is the temperature at which all solids have melted in a warming mixture.

Phase Diagram

LPI Soldermask

Liquid Photo Imagable Solder Mask is the outermost coating on a printed circuit board that sits between the copper and the components -- it's what gives PCBs their color.

Colored SolderMask

LPI is applied as a liquid coat that covers an entire PCB.  Then patterns of light are projected on the liquid and the high energy photons cause the material to harden and adhere to the PCB.

LPI protects copper traces and prevents liquid solder from migrating during the reflow process.