A PCB (printed circuit board) has more functions than just being a power facilitator as it provides mechanical support for the many components that are attached to it; it is the backbone of the electronic device, conforming to overall shape and dimensions, provides for signal fan out opportunities, etc. In addition and subject to distances and geometric arrangements between interactive components, it might control the electrical performance of the device t in and out of the active devices or components.

Sometimes the Cu traces are only in the surface of the board but most commonly the material also has internal circuitry that requires extra layers to provide conduits for power and signal flows. Multilayered PCBs are becoming fast the norm in the electronics industry as overall size decreases and number of functions goes up.

Certifications

Electronic devices are used in a variety of applications, in all manner of industries, across many different geographies and in so many areas in modern society that standardization is absolutely essential to enable rapid design adoption, which in turn allows faster time to market and time to money. The only way to insure that PCBs are designed and used in uniform fashion is to use reference certifications procedures.

JEDEC was the original attempt by the electronics industry in the early years of development to come to terms defining and establishing a series of procedures to not only design, manufacture and to certify electronic circuits but also to provide an attempt to unify the different design and manufacturing trends under one single decision body. It originally stood for Joint Electron Device Engineering Council but since the term like so many has mutated and now simply stands for the body of norms and procedures to allow certification of electronic devices.

These norms are open and free to use which has allowed their industry wide adoption, thus enabling the interoperability among different devices. For certification purposes, the norms define a set of requirements or tests the devices must comply with before they are accredited to be used. And in doing so, an entire science has evolved to determine appropriate conditions that simulate what the device will experience in the field; this is called reliability. For example, boards used for cell phones required to withstand at least 500 cycles from -25C to 120C; they need to withstand 1000 bending cycles, be humidity soaked and baked up to 5 times to simulate the surface mounting reflows. Below is an example of the JEDEC standards. Click the image to be redirected to the JEDEC site:

For very specific applications, like military or medical fields, there are additional, more stringent norms that guide the design, manufacture and application of devices suited for those particular fields. Just to give an example, for the US military the riding norm that directs the use and application of electronic devices are condensed in the Mil Standard.

ROHS

A very recent regulation that is affecting the electronic industry worldwide is the European RoHS/WEEE. It stands for Restriction of certain Hazardous Substances in Electrical and Electronic Equipment and it was put in effect in July 2006. Although originally intended only for European Union’s country members; its effects quickly affected all areas of the industry globally. This directive regulates the use of six substances in the manufacture and use of electronic devices: lead, mercury, cadmium, hexavalent chromium, polybrominated phenyl, and polybrominated diphenyl ether.

WEEE site

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