Lead-Free Board Material Reliability

There are numerous laminates available to the PCB designer today. Some of these laminates have been around for a number of years and the designers and OEM's understand their capabilities and limitations. However with the advent of lead free solders and their higher processing temperatures new laminates that are designated "Lead Free Capable" are appearing. These products while tested for consumer products have not necessarily been qualified for more complex PWB designs where peak SMT reflow temperatures on the PWB surface tend to be significantly higher with the potential reulst of internal delamination. This project conducts extensive testing of a selection of latest generation laminates and pre-pregs to measure their reliability in these higher SMT reflow environments. 

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Idea Information

Problem: 

Identify and characterize the assembly compatibility and reliability of a significant number of “lower” cost PWB materials subjected to multiple Pb-free assembly reflow cycles (6X @ 260˚C) with sufficient data to understand the reliability implications to member company use environments.

Definition Information

Approach: 
  • Expand data on Via Integrity to larger list of potential materials – including Far East Sources.
    • Low cost FR4’s from Far East Manufacturers
    • Limited number of High Frequency/High Speed Materials
    • A few Halogen Free Materials
  • Evaluate High Layer Count/High Resin Content Effect
    • Four board stackups:
      • 20 layer ~58% and 69%RC, .116/.118 thick
      • 6 layer, .062 thick, 48%RC,
      • 6 layer, .116 thick, 45%RC
    • Baseline – Turbo 370 and 370HR baselines on all .116 constructions
  • IST as part of test vehicle design for direct comparison of IST to Air to Air
    • Note - Acceleration factors for IST are also very high – such that a few cycle variation can affect years of field life
  • CAF PTH-PTH wall test section to evaluate the results of Pb-Free reflow on CAF performance
    • Limited to .016 hole wall to hole wall and .010 hole wall to hole wall
  • Evaluate Electrical Performance data and any effect of Pb-Free reflow on materials
  • Future Phase: Confirm/Determine Coffin Manson equation acceleration factor coefficients.
    • Requires multiple thermal cycle test conditions ($)
    • Build boards now – hold additional T/Cycling for future “phase” – budget dependent
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