0402chiprlc制程與不良品分析流程-版本2-在線瀏覽
2025-02-15 23:20本頁面
【正文】 Plated thruholes: 因錫膏的毛細現(xiàn)象 ,via會搶 pad上的錫 ,造成錫少或空焊Design techniques to avoid Design techniques that work解決方法 :? 限制 trace數(shù)量 ,減少錫遷移? 對稱設計 ,降低零件轉(zhuǎn)動可能? 禁止 pad上有 via或 Plated thruholes AMBIT Microsystems Corporation Mask Design1Solder Mask Materials:?Dry film laminate (3~4 mils)?Screened wet film (~9 mils)?Photoimagable liquid solder mask (~6 mils)?Misregistration of solder mask artwork or wet film solder mask slump can obscure or contaminate a pad surface causing excessive solder balls or defective solder joints.Note: 目前 Ambit使用 PCB的綠漆厚度約為 mil. AMBIT Microsystems Corporation Mask Design2Over thickness 2 mils ==Detectable tombstone Improvement:? 使用厚度小於 2 mils的綠漆? 去除 pad間的綠漆 ,排除墓碑 的機會 AMBIT Microsystems Corporation7. Component Orientation and Location IC long axis // reflow direction Chip long axis reflow directionIDEA DESIGN Consideration of Stress Distribution have the greatest deflection and stress at least away from the board edgeHigh stress areas for mounting and depanelingHigh stress areas for handlingTab shearing stressPrerouted corners to minimize defects12mil 12milAt least mm AMBIT Microsystems Corporation8. Thermal vs. Mechanical Damage Thermal damage?對 chip RLC而言 ,thermal造成的 crack現(xiàn)象很少見?修護是造成 chip RLC 零件 thermal shock damage主要過程?Crack通常位於上表面且為單一 crack. Pick and place machine damage?Bottom centering damage 少見?Top centering and vacuum pickup bit damage 常見?Internal centering Damage 無法從外觀看出?Post solder handling damage 板彎造成 AMBIT Microsystems Corporation?Vacuum pickup bit and top centering damage?Internal centering Damage due to centering jaw force? 過大 Z軸置放力造成? Damage不明顯 ,MLCC的 損壞通常位於表層或 內(nèi)部電極? 外觀為圓形或半月形Centering jaw force concentration(舊式置件機 ) Resulting visible top surface cracks?Impact fractures are typically located 10~15mils from the top surface hidden under the termination.?Internal crack does not fail qui
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