The HDPUG Guideline for Producing Pb Free Printed Circuit Assemblies

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HDP User Group releases new Guideline for producing Pb Free printed circuit assemblies.

reducing the costs and risks for the Electronics Manufacturing industry when using advanced electronic packaging and assembly

Manufacturing products with Pb-Free solders has become an established practice following the introduction of legislation across Europe in 2006 in response to the European Union directive on the Restriction of Hazardous Substances (RoHS). The legislation outlaws the use of certain substances including lead (Pb) in the production of electrical equipment and it applies primarily to consumer based products with a wide range of exemptions in place for applications demanding extended lifetime and high reliability performance.

In preparation for the switch away from products manufactured with tin-lead (SnPb) solders, the High Density Packaging User Group (HDPUG) released in 2004, a comprehensive guideline on best practise for general purpose Pb-free printed circuit assembly. As an industry consortium with members representing all elements of the electronics supply chain, the group recognised the need for a reference document that would help to drive common processes and assist designers, manufacturers and materials suppliers in their preparations for one of the biggest changes that the electronics manufacturing industry has ever faced. Drawing on the considerable technical expertise within the group and from the extensive development and testing projects undertaken, the 50+ page document proved an instant success with downloads from HDPUG's web site running into thousands each week in the run up to RoHS implementation date.

With several years experience now under its belt and with relatively few problems reported by the industry one would be forgiven in thinking that the challenges of Pb-free soldering are behind us. However with the absence of any long term field performance data, manufacturing mission critical products with Pb-free solder continues to throw up a number of concerns for many producers. Reliability data of products operating under normal functional conditions and over many years is the missing piece of the jigsaw that allows researchers to have complete confidence in the accelerated life time testing procedures that have been developed to predict solder joint performance. In the absence of this vital piece of information, many producers of products falling into an exemption category within the RoHS directive have preferred to date, to delay transitioning their products away from proven SnPb soldering technology.

Although successful so far, the strategy to defer changing to Pb-Free solder processes is increasingly being challenged by the diminishing availability of compatible SnPb finished /balled components. Component manufacturers responding to high volume Pb-free product demand from the consumer markets, continue to terminate Pb containing product lines as they become cost prohibitive to supply. This leaves manufacturers of RoHS exempt equipment with a major dilemma on whether to procure components on a lifetime buy basis, post process components (e.g. lead solder dipping, BGA reballing) or adopt Pb-free components and solder in their products.

With this scenario in mind, HDPUG has produced an updated Pb-free guideline which focuses on the specific issues that face producers of products with high reliability and extended service life expectations. Project leader Thilo Sack from Celestica Inc explains; "The perception exists that since Pb-free has largely been implemented successfully in consumer applications that there should be no issues in transitioning those products still making use of the exemption. The aim of this revised Pb-Free guideline is to raise awareness and bring attention to the outstanding issues that still exist in the supply chain from the learning to date which will challenge the easy transition of currently exempt products to Pb-free."

Preparation of the document has been supported by senior technical representatives from several of the industry's leading system integrators, all of which are at the forefront of their companies' Pb-free product development programs. They were joined by technologists from major players in the component/materials supply and printed circuit board fabrication and assembly fields. The guideline provides a valuable status report on the progress that has been made in Pb-Free technology since mainstream adoption in 2006 and the issues that remain for producers of currently RoHS exempt products. It is structured into chapters focusing on current legislation across the globe, market drivers, materials and component considerations, manufacturing issues/solutions and transition/ongoing cost impacts.

While there are still a number of outstanding concerns about the performance of Pb-Free solder alloys over an extended period of time, much of the data produced by the industry to date indicates that Tin Silver Copper (SAC) solders are an acceptable substitute for Tin Lead eutectic solders in a wide range of (but not necessarily all) applications. However, there remain some questions to be answered. In response, HDPUG has embarked on a broad range of reliability related studies over the last 5 years to examine the performance of Pb free materials and the impact of adopting these materials into mainstream electronics. Many of the results and conclusions derived from these projects are incorporated in the guideline.

The HDPUG Pb-Free guideline is available for download at

About HDP User Group
HDP User Group ( is a global research and development organization based in Scottsdale AZ, dedicated to "reducing the costs and risks for the Electronics Manufacturing industry when using advanced electronic packaging and assembly". This international industry led group organizes and conducts R&D programs to address the technical issues facing the industry, including design, printed circuit board manufacturing, electronics assembly, and environmental compliance. HDP User Group maintains additional offices in Austin, Texas; Stockholm, Sweden; and Tokyo, Japan.

For more information, visit HDP User Group on the Internet at
or contact Darryl Reiner at darrylr (at) hdpug (dot) org, phone number +1 480-951-1963.


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Kim Jorgenson
HDP User Group
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