| Frequently Asked Questions about RoHS |
Q. What is the purpose of the RoHS (Restriction of the use of certain Hazardous Substances)?
A. The EU has passed Directive 2002/95/EC of the European Parliament that restricts the amount of certain hazardous substances in electrical and electronic equipment. The substances are lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl and polybrominated biphenyl ethers. These substances are limited to 1000 parts per million (0.1%) with the exception of cadmium which is restricted to 100 parts per million (0.01%). For the printed circuit board industry the restrictions on lead and polybrominates (used as flame retardants in plastics, i.e. epoxy resins) are far reaching.
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Q. How does the RoHS directive affect my printed circuit boards?
A. For many years the electronic industries have used tin/lead solder to join the components to the printed circuit boards. The board fabricators have also used tin/lead solders as a surface finish to protect the copper from corrosion. The 63/37 tin lead ratio of solder fit well within the assembly thermal parameters and the physical limitations of the base materials. The standard FR-4 laminates were also compatible with the wave solder systems. RoHS requirements have changed the rules. No longer are the tin lead solders allowed!
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Q. How does the restriction on leaded solder affect my PCB's?
A. The printed circuit board assembly industry will have to increase the thermal profile and dwell times of their soldering processes in order to process the lead free solders. These increased time and temperatures requires materials with a high Td to allow for multiple passes. All of the new Lead Free material offerings currently on the market will meet these requirements.
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Q. If tin lead solder finishes can no longer be used, what plating finishes are available for my printed circuit boards?
A. Sierra Proto Express has a variety of plating finishes available that are compatible with the RoHS directive. These include lead free solder (Lead free HASL), lead free immersion white tin, immersion silver, OSP's, electroless-nickel immersion gold (ENIG), soft bondable gold and full body gold finishes. These finishes have been tested and approved for the higher temperatures required in the assembly processes.
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Q. What are some of the characteristics of common finishes of RoHS compliant plating finishes?
A. Refer to the following table:
| RoHS compliant Plating Finishes |
| Finish |
Coplanar Deposit |
Shelf Life |
Rework Cycles |
Relative Cost to HASL |
| Lead Free Solder |
No |
9 months |
Multiple |
Equivalent |
| Immersion silver |
Yes |
12 months |
Multiple |
Higher |
| Immersion White Tin |
Yes |
12 months |
Multiple |
Equivalent |
| OSP's |
Yes |
12 months |
Limited |
Equivalent |
| ENIG |
Yes |
12 months |
Limited |
Higher |
| Soft gold |
No |
12 months |
Limited |
Higher |
| Hard gold |
No |
12 months |
Limited |
Higher |
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Q. Are there changes to the laminates that will be used for RoHS approved printed circuit boards?
A. Yes our laminate suppliers have developed resin systems used in the laminates that are compatible with the higher temperatures required for assembly. Our lead free laminates are also UL approved. The laminate has a Td of (decomposition temperature) 364 degree celcius.
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Q. Can Sierra Proto Express supply a Certificate of Compliance to the RoHS directive?
A. Yes, as well as a letter of compliance from our laminate suppliers that the materials are RoHS compatible.
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Q. What is the best plating finish for RoHS compliant assembled printed circuit boards?
A. That depends on your product, application and method of assembly for your printed circuit boards. You should consult your assembly vendor for the best finish for your application.
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Q. Will your RoHS compliant printed circuit boards take longer to process?
A. There is an increase in time of lamination process of multilayer boards, however there will not be an in the lead time of your orders.
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Q. Are different materials available that are RoHS compliant?
A. Yes, the following table contains common laminates that may be of interest:
| Temperatures and Times |
| Laminates |
Glass Transition Temp. (Tg) (Degrees Celcius) |
Decomposition Temp. (Td) (Degrees Celcius) |
T-260 |
T-288 |
| IS410 |
180 |
350 |
> 60 minutes |
> 15 minutes |
| Nelco 4105-11 |
175 |
360 |
30 minutes |
Unavailable |
| Polyclad 370HR |
180 |
Unavailable |
> 60 minutes |
5-20 minutes |
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Q. How do I specify that the boards need to be RoHS compliant?
A. 1. You may add a note to your drawing, purchase order or quote information (preferably all three) that states "Fabricate to meet EU RoHS Directive".
2. Request a Certificate of Compliance to the RoHS directive.
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Q. Will the RoHS compliant printed circuit boards have markings to identify them as lead free?
A. Yes, the words lead free or LF will be silk screened on the board near the Sierra Proto Express logo.
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Q. How do I order lead free PCBs from Sierra Proto Express?
A. If you have a lead free board design and want a quote, please go to our custom quote form
and upload your file. We will send you a quote within two hours.
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