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The creation and building of a Pb-free product: a case study in designing and building Pb-free 128Mb USB memory modules.

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Over the past five years, Speedline Technologies has actively worked with numerous customers on Pb-free process implementation, both in process equipment requirements (our primary business) and process development. Process development projects--internal and with several major soldering material suppliers and academic institutions--are ongoing. In late 2004 we decided to design and build a functioning Pb-free product. Among our reasons: to gain additional understanding of Pb-free product design and manufacturing issues; to collect meaningful data during the build to identify defects that can be expected; to have product to give customers during trade shows or other events to demonstrate our Pb-free process expertise. We chose to build a 128Mb USB memory module.

This case study of our experience includes board design, stencil design, Pb-free solder paste selection, support tooling design, printing process development, reflow oven profile creation, quality data, defect detection and other observations.

With several Pb-free process projects finished and several more planned, we concluded we had done virtually everything in Pb-free process development short of actually building a working Pb-free product. What else could we do to better understand all the Pb-free process issues? We conceived the idea to build a working Pb-free product. After considering a number of product ideas the USB memory module seemed to best satisfy our requirements of budget, complexity, marketing (a tradeshow "giveaway") and, most important, education. The 128Mb size module is usable and fit our budget.

The first step for our memory module was to create a circuit design. We built a prototype (breadboard) using the schematic. Once the prototype was built and tested we immediately started designing the circuit board. We had the required mechanical size of the board since we had selected the plastic case for our 128Mb USB memory module. We acquired the specification for all components and supplied them along with the required board size to the designer (Table 1, online).

Next, we built two models using the PCBs we designed and the components from our bill of materials. Fortunately, the two models worked the first time with no component or circuit changes required. We then started purchasing all the components to build 1,100 units. Before ordering boards, we had to design the working panel or palette that would contain multiple individual memory module circuits. The individual circuits were small (0.56 x 1.28") so we elected to build panels containing several individual circuits.

The authors, Srinivasa Aravamudhan, Joe Belmonte, Anand Bhosale, Alden Johnson, Karl Moore and Dr. Gerald Pham-Van-Diep, wrote this article while at Speedline Technologies (;

Srinivasa Aravamudhan, Joe Belmonte, Anand Bhosale, Alden Johnson, Pat Mattero, Karl Moore and Dr. Gerald Pham-Van-Diep
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Title Annotation:Pb-Free Case Study
Author:Pham-Van-Diep, Gerald
Publication:Circuits Assembly
Date:Apr 1, 2006
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