Advanced PCB Troubleshooting

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Information about Advanced PCB Troubleshooting
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Published on July 9, 2009

Author: ryansmta

Source: authorstream.com

Advanced PCB Trouble Shooting-The Good, the Bad and the Ugly : Advanced PCB Trouble Shooting-The Good, the Bad and the Ugly Michael Carano OMG Electronic Chemicals Agenda : Agenda Introduction Innerlayer Treatment/MLB fabrication Opens, shorts, delamination Other Lamination/MLB issues Material selection Misregistration PTH -Electroless copper/metalization issues PTH defects-voids, ICD, Hole wall pullaway Electroplating related issues Mouse bites Cosmetic defects Copper defects-barrel cracking, dog-boning Plating distribution and relationship to PCB reliability Final Finish related issues Black Pad Trench etch Champagne Bubble and other Surface finish defects Solderability failures and final finishes General session MATERIAL MOVEMENTPrepreg during/after cure drives the relative positions of the layer images : MATERIAL MOVEMENTPrepreg during/after cure drives the relative positions of the layer images MATERIAL MOVEMENTPrepreg during/after cure drives the relative positions of the layer images : MATERIAL MOVEMENTPrepreg during/after cure drives the relative positions of the layer images More prepreg makes it worse Without proper scaling Drilled hole Voids : Voids Type A and Type B -ICD : Type A and Type B -ICD Blow Holes and Wedge Voids : Blow Holes and Wedge Voids Gas Bubble Pit : Gas Bubble Pit Photo courtesy of DuPont Causes of Micro-Nodules : Causes of Micro-Nodules Micro-nodules are a result of rapid crystal growth in the z-axis during acid copper plating Copper foil imperfections DIFFICULTY FACTOR : DIFFICULTY FACTOR Aspect Ratio Difficulty Factor 10:1 10:1 1 2 Panel Thickness2 _____________________ Hole diameter Direct Cause Mechanism For Microvoids: : Direct Cause Mechanism For Microvoids: ‘Copper Caves’ are small (~1 µm) enclosed cavities in copper lands, under the ImAg plating, in as-received PCBs. ImAg Copper Land Cave PCBs with caves resulted in microvoids, PCBs without caves resulted in no microvoids. Cave is fully enclosed: ImAg forms a ‘roof’ over the cave. 1 µm Walls and floor of cave are oxidized copper. 1 µm ‘Chimney’ SMTAI 2009San Diego, CA : SMTAI 2009San Diego, CA

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