Circuit Mission Ltd

www.smartgroup.org
The SMART Group download page provides a wide range of technical articles related to the assembly process and common process defects.

http://www.pcbstandards.com
Useful chart comprehensively illustrating and explaining all aspects of pcb manufacture. Site index for vast collection of free downloadable data relevant to pcb design, e.g. pad patterns, current capacity calculators, impedance calculators, flex circuit design advice, etc.

http://www.ipc.org/
Large amount of free downloadable CAD information. eg. smd land patterns, impedance calculators, IPC Standards, etc.

http://www.allflexinc.com/guid.shtml
A comprehensive downloadable flexible circuit design guide.

http://www.yelo.co.uk/area3/pcbtester.htm
Guidelines for Testing PCB’s. The following are guidelines to assist companies who are laying out PCBs which they wish to test using bed of nails, both in-circuit and functionally.

http://www.emclab.umr.edu/pcbtlc2/index.html
PCB track impedance calculator which calculates the characteristic impedance and per-unit-length parameters of typical printed circuit board track geometries.

http://www.npl.co.uk/ei/news/faqs.html
The most frequently asked questions and answers on lead-free soldering and components. Highly recommended.

http://www.environment-agency.gov.uk/netregs/legislation/
Gives details on the Restriction of Hazardous Substances in Electrical and Electronic Equipment (ROHS) Directive (2002/95/EC)

It effects manufacturers, sellers, distributors and recyclers of electrical and electronic equipment containing lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls or polybrominated diphenyl ethers. This Directive covers the same scope as the Directive on waste electrical and electronic equipment (WEEE) except for medical devices and monitoring and control instruments. It also applies to electric light bulbs and light fittings in households.

http://www.npl.co.uk/ei/research/leadfree.html
National Physics Laboratory: reports on the scientific programme on measuring and modelling the materials properties impact on solder joint reliability.

http://www.envirowise.gov.uk
Envirowise offers UK businesses free, independent, confidential advice and support on practical ways to increase profits, minimise waste and reduce environmental impact. It explains the effects of the Directive on waste electrical and electronic equipment (WEEE).

http://www.isola.co.uk
This is the site of Isola, a major laminate supplier with the technical specifications for a wide variety of laminates. e.g. CEM1, FR3, FR4, FR5, BT resin, Polyimide, Cyanate ester, FR5 aramide.

http://www.rogerscorporation.com Rogers are a major manufacturer of high frequency laminates. This site contains technical specifications for PTFE laminates, and other materials. There is also a downloadable impedance calculator.

http://www.graphicode.com
Download the GC-Prevue gerber viewer from this site. It is highly recommended and free of charge.

http://www.numberone.com/links.htm
The site of the authors of EasyPC software. You can download demo software. It also contains links for downloadable component data sheets.

http://www.polarinstruments.com
This site mostly deals with controlled impedance issues. It offers free downloads of useful software such as a 2D Field solving Impedance design system supporting 39 controlled impedance structures. Other items are freeware PCB track resistance calculator, gerber files for a typical impedance test coupon, graphical pcb test and repair software which replaces schematics and reads most popular CAD formats plus IPC.

http://www.ipc.org/
This site has the IPC Standards.

http://www.ul-europe.com
The UL Library helps with standards, certification issues, technical requirements, and how they are applied. It also has downloadable marks.

http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/index.htm
The Underwriters Laboratory database of approvals is an essential tool if you are selling into the US. Searches can be made by a company name, UL file number, or keyword.