Important Questions on RoHS Compliance Answered – II

Today, the demand for RoHS compliant PCBs has grown. In the previous post, you might have got a basic idea on these PCBs. In this installment, we will discuss a few important questions on these PCBs.

ROHS Compliance

Some Important Questions on the RoHS PCBs Answered

Which is the best RoHS compliant surface finish?

  • The answers may differ, however, most PCB manufacturers may agree upon immersion silver. This surface finish has been around much before the RoHS requirements came into play. When used properly, immersion silver coated PCBs can have a long shelf life. Also, the PCBs can withstand extreme temperatures, and environment conditions. Silver immersion soldering doesn’t require a special fixture. Other additional characteristics include:
  1. Low contact resistance
  2. Excellent co-planarity that provides a flat surface for solder paste application.

Are special materials used for lead-free circuits?

  • Lead-free soldering have higher temperatures than regular lead soldering substances. The temperature is typically 30ºC higher than the standard lead/tin solder. For instance, peak temperatures of lead-free solder is around 250ºC instead of 220 ºC of tin/lead solder. Thus, high temperature material is selected for building these boards.

Does the RoHS processing impact the performance of a printed circuit board?

  • No. The temperature of the material used for making the ROHS compliant laminate doesn’t vary much from the regular lead-based laminate. Hence, there is no significant change in the PCB characteristics during the processing.

Are there any RoHS exemptions?

  • Yes, there are exemptions. This can be referred on Annex III of Directive RoHS 2011/65/EU – Article 4 (1). The annex provides information on the exemption number, scope, description, as well as the dates of applicability. Exemptions are mentioned for the specific applications, where the elimination of the prohibited substance becomes impracticable or where the available components may have adverse effect on the environment.

Do RoHS compliant printed circuit boards cost more?

  • The RoHS compliant boards may be available at little different prices than the regular boards. However, the manufacturers allow you to select between various lead-free surface finishing options.

What is the shelf life of the RoHS boards?

  • The shelf life may vary. As a good manufacturing practice, it is always better to store assemblies and components in their original packaging, and in a temperature controlled environment. Also, extreme care should be taken to ensure that the PCBs are not exposed to extreme temperature or humidity for a long period of time.

Is it possible to make multilayer ROHS boards?

  • Yes. Many circuit board manufacturers allow their clients to build multilayer RoHS boards.

Why has Rigiflex Adopted RoHS (Pb-free) Assemblies and Components?

Rigiflex has adopted RoHS compliance, in response to the rising global concerns about the hazardous effects of lead and other substances employed during the manufacturing of PCBs, and other electronic assemblies. Many regulatory groups across the globe have implemented the legislation demanding companies to adopt RoHS compliance by using lead-free components, as well as PCB manufacturing processes. Adhering to these regulatory compliances, many clients approach Rigiflex to provide RoHS products, which use lead-free substances. This RoHS transition has not only helped us adhere to the compliance, but also allowed us minimize our carbon footprint.

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