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ID:32718648
大小:6.81 MB
页数:61页
时间:2019-02-15
《表面组装用无铅焊膏的研究与评价》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、摘要随着电子行业和表面组装技术(SMT)的发展,焊膏已经成为电子工业中元器件组装最为重要的电子材料。本文通过对实验室已开发的SYS305无铅焊膏及助焊剂的各项性能进行分析总结,从助焊剂成分、合金粉比例和焊后残留物可靠性方面出发,针对存在问题,进行优化,开发出了一种性能优良的无铅焊膏SYS305-H,.并对其进行了焊球、润湿性、塌陷等方面的研究和综合评价。主要取得以下成果:1通过对原有SYS305无铅焊膏及助焊剂进行各项性能评定,发现其焊点腐蚀严重、焊后残留多且无法凝固成固体、焊后绝缘电阻偏低,根源为原助焊剂配方中的活化剂配比不合理、溶剂熔点过低、松香含量过高。2通过调整活化剂的
2、比例,降低了助焊剂的腐蚀性;开发了新的溶剂体系,改善了助焊剂的润湿性,提高了焊后绝缘电阻值,并增强了助焊剂溶剂体系的溶解能力;改进了松香的复配比例,降低了助焊剂的固含量,增加了助焊剂的粘度,提高了焊后残留物的成膜性。3针对新改进的助焊剂,确定了最佳合金含量为88.O%,同时研究了合金粉的比例对焊膏流变性能和印刷性能的影响,4通过对SYS305.H进行各项焊膏检测标准的评定,得到本焊膏焊球试验评定结果为l级;润湿性试验评定结果为1级;塌陷试验塌陷率为0.10;焊后焊点饱满、光亮;焊后残留物为无色透明固体,无粘性,且残留少。关键词无铅焊膏:助焊剂;合金含量;残留物ABSTRACTW
3、iththedevelopmentofelectronicindustryandsurfacemounttechnology(SMT),solderpastehasbecomeoneofthemostimportantelectronicjoiningmaterialsinelectronic—industry.T11ispaperanalyzedthepropertiesoftheSYS305lead—freesolderpasteandflux.Anewtypefluxhasbeendevelopedbyadjustingtheelementsofflux,thepropo
4、rtionofsolderpowerandthereliabilityofresidues.Thesolderballtest’wettabilitytestandslumptesthavebeencarriedon.Theresultsshowthat:1Theoriginalsolderpastecouldformweldingspots,butthespotshavebeenoxidizedseriously,theresiduesafterweldingcannotbecurdled,andsurfaceinsulationresistanceWastoolow.The
5、reasonisthattheratioofactivatorisunreasonable,thesolvent’Smeltingpointisexcessivelylow,therosincontentisexcessivelyhigllintheoriginalflux.2Throughchangingtheratioofactivator,thecorrosionoffluxhasbeenreduced;Goodsolventcomponentsystemswhichcallimprovetheflux’Swettability,in.creaceitssurfacein
6、sulationresistanceandhigherdissolvingabilitywasbroughout.Choosingnewratioofrosincomponentstodecreasethesolidcontent,enhancetheviscosityoffluxandmaketheresiduessolidification.3Accodingtothenewfluxsystem,whenthesolderpowerWasaccountfor88.0%ofthesolderpaste,itcanbebetterprintedthantheotherones.
7、Theinfluenceofthesolderpower’sproportiontorheologicalpropertiesandprintcapabilityhasbeenstudied.4Throughassessingthestandardofsolderpaste,thesolderballtestandthewettabilitytesthavereachedthefirstgrade;theslumprateisO.10;theweldingspotshavegoodappea
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