Sunday 15 December 2013

PCB Design Services For The Electronics Industry

By Jeannie Chapman


PCB design services must be provided by skilled professionals with enough experience to come up with the optimum physical layout for a client's printed circuit board. They must have the resources and capability to deploy the latest CAD software and other PCB design tools to handle complex designs and all kinds of boards. Generally speaking, the designing process has the same multiple stages irrespective of the type of board and the layout, and it all begins with schematic captures.

Information about three key aspects of the project must be provided by the client to the designer. The schematic is obviously the most important thing. Note that it may also be in the netlist format. The netlist file contains the circuit's connectivity details and descriptions for the components.

The client also has to provide the BOM (bill of materials) that lists all the components to be used and their footprints, although some designers also offer assistance with component footprint capture. Then there's also the board outline that must be provided. The outline, schematic/netlist and the BOM together constitute all the necessary information that will be used for designing the PCB.

There are many intermediate techniques used in several stages that build on the schematic or netlist. These functions include things such as library development, signal integrity checks, stress analysis, thermal simulation and EMI checking. All this leads up to the generation of the gerber file. This is the most commonly used format used for transferring complete PCB images ready for manufacturing.

The designer must be capable of coming up with solutions for complicated analog, digital, RF and mixed PCBs. Then there's also the type of board, which can be single-sided, double-sided or multi-layered. The board's size may vary, and so can the pin densities and component quantities.

The designer also has to decide the board characteristics. This is the method that must be used for mounting components and creating circuit traces. The most popular technique that is now in use is called surface-mount technology.

Components on boards that use this technology have their end caps soldered on the same side as the components themselves. This is hugely different from earlier techniques such as through-hole boards. The leads of components in such older boards were inserted through holes and soldered on to the traces on the other side.

Designing new boards is just one part of the services offered by PCB designers. They may also be asked to perform other functions such as evaluate designs, along with the components used and their footprints. Clients sometimes ask them to assist with procurement of prototypes and check for availability and pricing information against the BOM contents.

There may, in fact, be other PCB design services required even after delivery of the end product. Customers often need to do minor changes to the design right away and on an ongoing basis, and reorders are also on the cards. Designers are sometimes asked to reverse engineer the process, starting with gerber files. Coming up with a netlist or schematic from a gerber file helps the client rebuild the circuit to implement large-scale changes.




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