The Electronics Source Book
September 21, 2005
iNEMI releases standards for
RoHS transition
The move to lead-free components mandated by the European Union’s Restriction of Hazardous Substances (RoHS) has sent shockwaves of confusion through the electronics industry. The EU sent out a directive demanding green products, but component manufacturers have been left to their own devices to figure out how to effectively test their green components to the satisfaction of their customers. Parts suppliers have also been struggling with communicating the component material make up to their customers. They have been inundated by customer requests for material composition and of course each customer requests the information in a different format.
The International Electronics Manufacturing Initiative (iNEMI) has attempted to resolve this difficult situation by developing standards in conjunction with fellow industry groups. The idea is to create formats that suppliers can adopt that are recognized by their customers as well as the governmental bodies that will police the component industry after the July 1, 2006 RoHS deadline.
What constitutes a reliable lead-free component? Each component manufacturer has its own internal testing process, but now, there is also an outside standard that can be applied so customers can gain confidence their components will be reliable. iNEMI has released two documents intended to help manufacturers reduce the risk of tin whisker growth in lead-free products. Tin whiskers are those pesky tin filaments that grow on a pure tin finish under stress and can cause component failure.
The first document is JEDEC standard JESD22A121, “Test Method for Measuring Whisker Growth in Tin and Tin Alloy Surface Finishes.” The second is the updated “Recommendations on Lead-Free Finishes for Components Used in High-Reliability Products,” which comes from the iNEMI Tin Whisker User Group.
The JEDEC document details a suite
of tests that provide an industry-standard method of measuring and comparing
whisker propensity for different plating or finish chemistries and processes.
The standard also provides a consistent inspection protocol for tin whisker
examination and a standard reporting format.
Based on data from around the globe plus extensive testing by iNEMI members and
others, the JEDEC standard identifies three test conditions that appear to be
suitable for monitoring tin whisker growth. Two provide for isothermal
conditions with controlled humidity and the third is a thermal cycling
condition. The test method outlined in this standard can be downloaded for free
from the JEDEC website (www.jedec.org or www.jedec.org/download/).
The iNEMI Tin Whisker User Group has published revised recommendations for lead-free component finishes to be used in high-reliability products, which is intended to help manufacturers minimize the risk of failures due to tin whiskers.
This revision is based on the latest data available and reflects the uniform
test requirements established in JESD22A121. Recommendations have been
organized to provide easy-to-follow guidance on the various lead-free finish
options. The team has added tables addressing every finish and base
material offered commercially and also provides user acceptance guidelines for
the various combinations. They have also added finish recommendations for
separable connectors, buss bars and heat sinks.
The iNEMI Tin Whisker User Group previously issued a document, “Tin Whisker
Acceptance Test Requirements,” that has been adopted by many users and has also
been submitted to JEDEC and IPC for formal standards creation. Both sets of the
User Group recommendations are available on the iNEMI website at www.inemi.org/projects/ese/tin_whisker_activities.html.
The supplier declaration standards are designed to give component manufacturers a format that can be used across their entire customer base, so the supplier will only have to create one declaration for each component. These standards were developed over a year by joint efforts with IPC, iNEMI and RosettaNet.
From these efforts have come a
family of supplier declaration standards, namely two in draft form, IPC-1751,
“Generic Requirements for Declaration
Process Management,” which describes
all generic requirements including company information and, IPC-1752, “Materials Declaration Management,” which
establishes electronic data formats and provides standardized forms to simplify
the exchange of materials declaration information.
The draft standards and PDF forms were released for industry review and can be
accessed at www.ipc.org/IPC-175X.
Once all feedback has been reconciled according to the ANSI (American National
Standards Institute) standards approval process, the standards will be issued.
Hopefully, the new standards for testing and material declarations will take some of the persistent confusion out of the electronics industry’s awkward transition to green products.
1. Getting parts
around the world
2. Global logistics: every part to its right place
3. Environmental
regulations become patchwork nightmare
4. Finding
leaded parts after the RoHS deadline
5. What
happens to leaded parts after RoHS
6. Engineering
jobs are migrating globally
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