The finish plating of a printed circuit board is very critical because it serves as protection to the exposed copper circuits and it also ensures that the soldered surface is intact, which is needed in assembling components to the board. The finish plating is essentially some type of coating between a bare board PCB and a component.
Printed circuit boards (PCBs) have surface copper finishes that need to be protected. If left without a finishing, it will characteristically oxidize and deteriorate. If this happens, the circuit board will be unusable.
Companies have several choices when it comes to types of surface finishes. PCB companies offer various choices. The most common choice is the Lead Solder. Other choices are Lead-Free, Immersion Tin, Organic Solder ability Preservative (OSP), Electroless Nickel Immersion Gold (ENIG), Immersion Gold, and Immersion Silver. In choosing the right finishing, companies have to adhere to regulations. PCB companies adhere to RoHS and WEEE standards.
What are RoHS and WEEE standards?
RoHS means Restriction of Hazardous Substances. It restricts the use of substances in electronic manufacturing that are deemed to be hazardous to one’s health. In a PCB manufacturing company, all the components that they use have to be tested for the presence of toxic substances such as Hexavalent Chromium, Lead, Cadmium, Mercury, Polybrominated Diphenyl Ethers, and Polybrominated Biphenyls.
The lead component should be no more than .1% of the material. On the other hand, WEEE stands for The Waste Electrical and Electronic Equipment Directive of the European Union. WEEE outlines several directives with the objective of enhancing the efficiency of resources, particularly electronic equipment. PCB manufacturing companies must adhere to both RoHS and WEEE standards. One such company is Imagineering Inc. Upon visiting their website www.pcbnet.com, visitors and prospective clients will find the WEEE approved seal and the RoHS compliance that they apply on their surface finishes.
Here www.pcbnet.com , you can get the various choices for clients. PCB Fabrication Company Imagineering, Inc. offers various finishes for clients. Clients get to choose among these types of common finishes: leaded solder, lead free solder, immersion gold, immersion silver, white tin, and OSP. All these finishes are RoHS compliant. The company has been a leading manufacturer and full turnkey contractor of PCBs since 1985. Being in the market for so long, the company has garnered quite a reputation in the industry, with various certifications and accreditations from the industry.
In their bid to be more responsive to the current needs of their customers, they always come up with innovations in customer support. Recently, their website www.pcbnet.com now offers a direct ordering form. When clients go to www.pcbnet.com, they can directly fill up an ordering form. The ordering form has board specifications such as part number, number of layers, finish plating, copper weight, dimensions, materials, and thickness. It also has choices for board quantities. Customers can complete the form online and submit to Imagineering Inc. in order to get a quote.
Companies consider many things in choosing the finish plating that they will use for their PCBs.
What are the major differences and benefits of choosing one type of finish over the other?
The most common type of surface finish is HASL, which can have either lead or lead-free components. This has the lowest cost and is available in most PCB production companies. It also has a long shelf life. However, the lead component option might be a disadvantage, especially for those companies such as www.pcbnet.com who strictly adhere to standards set by governing institutions.
The next type, OSP or Organic Solder ability Preservative are also called anti-tarnish preserves. It is a water based surface finish, that’s why it is environmentally-friendly and lead-free. It is cost-effective to use OSP because it requires low equipment maintenance and it is easily repairable. However, it has a short shelf life and it has sensitivity issues while it is being handled.
The next type of finish is immersion tin. It is a very good choice because it is lead-free and highly reliable. It is also cost-effective and it can easily substitute for reflowed solder. Some of its disadvantages are that it has some handling concerns such as limited rework, tin whiskering, and it contains a known carcinogen called thiourea.
Both immersion silver and immersion gold are very good choices. Their benefits far outweigh the cost. They are both RoHS compliant and have high stability. However, gold is quite expensive to use and silver has the tendency to tarnish.