smt概要-文庫吧資料
2025-02-22 06:20本頁面
【正文】 solder on the base metal. n Wettabilityn Resistance to soldering heatn Resistance of metallisation to dissolution401Intermetallic Compound411Solder Paste Storage Handling Considerationsu Stabilize paste to room temperature after refrigeration for a least 58 hours prior to useWhy? If paste is not returned to room temperature the viscosity will be higher than specification and stencilling will be poor. Water condensation inside the paste will occur.421Solder Paste Storage Handling Considerationsu Stir for 30 seconds, 2 revolutions per second with appropriate plastic spatula before useWhy? Some settling (flux separation) can occur, gentle stirring with plastic spatula (to avoid plastic jar scrapings) can only help.431Solder Paste Storage Handling Considerationsu Discard any paste remaining on the stencil at day’s end and never mix fresh and used paste together in a same jar.Why? Paste will lose some solvent during use resulting in higher viscosity。印壓過強造成滲漏易發(fā)生短路印壓不足鋼版上錫膏殘留易 產(chǎn) 生空 焊281關(guān)於基板與鋼版間隙 (GAP) 所謂間隙是指基板與鋼版之間的間隔，如果間隙過大時很容易發(fā)生錫膏流進反面的鋼版，造成錫膏量過多，易產(chǎn)生短路。相反如印刷壓力不足，也無法達到良好印刷效果，可能會造成漏印虛印等等現(xiàn)象。當(dāng)錫膏黏度太低，再連續(xù)印刷時易造成滲漏下塌而產(chǎn)生短路。m261關(guān)於印刷速度關(guān)於印刷速度 (Printer speed) 印刷速度如太快，會發(fā)生虛印、漏印或錫膏量不足 (錫膏印刷時下降未完全 )。221The Printing Process231DEK Infinity Stencil Printer241Common Stencil Types Electroformed (電鑄） Laser cut+電拋光蝕刻 Laser Cut 251Sele
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