封装中的材料.ppt

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1、11电子封装材料相关问题蔡坚2概要电子封装材料封装中涉及到的主要材料内引线材料模塑料引线框架材料芯片粘接材料封装基板与外壳材料焊接材料3Institute of MicroelectronicsInstitute of Microelectronics封装材料的范围能源、环境、材料、信息微电子的发展微电子封装材料同时涉及系统组装的材料简单的分类：金属、陶瓷、塑料4Institute of MicroelectronicsInstitute of Microelectronics电子封装材料的性能电特性绝缘性质、击穿、表面电阻，热特性玻璃化转化温度、热导率、热膨胀系数，机械特性扬氏模量、泊松比、

2、刚度、强度，化学特性吸潮、抗腐蚀，其它密度、可焊性、毒性，5Institute of Microelectronics电子封装材料ChipEncapsulationPCBPrinted Circuit BoardChipSubstrateSolder JointLeadframeSolderJointWireUnderfillSolder BumpMolding CompoundPin Thru.HolePackage(Substrate or leadframe)6Institute of Microelectronics内引线键合材料27常见引线键合材料引线键合常用于芯片与载体（或基板）或

3、引线框架之间的互连常用的引线材料有Au、Al、Cu（包括用于TAB）、AlSi(1%)丝键合的模式主要有球焊（金丝）和楔形焊（铝丝）金丝用于塑料封装，铝丝用于陶瓷和金属封装？8内引线键合材料的特性电性能热性能机械性能参考讲义128-1339Institute of MicroelectronicsInstitute of Microelectronics金丝键合系统消费类电子产品中最常用的键合方式金丝-铝键合区金丝-镀金键合区掺杂的金丝金丝：软Be，5-10ppm；Cu，30-100ppm10Institute of MicroelectronicsInstitute of Microelec

4、tronics引线键合的优缺点优点细间距，高速自动键合，高导电，铝键合区缺点金属间化合物Kirkendall效应电流限制11Institute of MicroelectronicsAu-Al金属间化合物300C以上的使用环境，容易发现“紫斑”；125C，可能产生一系列的金属间化合物。12Institute of Microelectronics31314Kirkendall效应异种金属之间的互扩散不同的扩散速度温度、结构、15Institute of Microelectronics金丝与其他介面的键合Au-CuCu3Au，AuCu，Au3Cu：200-350C无金属间化合物产生Au-Au最

5、好的键合高温应用16Institute of Microelectronics铝（硅铝）丝键合系统Pure aluminum is too soft.So alloyed with 1%Si or 1%Mg to provide a solid-solutionstrengthening mechanism.Au-AgAl-OFHC CuAl-Ag plated LFAl-Ni75um Al can be used for power devices.17Institute of MicroelectronicsInstitute of MicroelectronicsCl-的影响“白毛”Al

6、(OH)3 +Cl-Al(OH)2 +OH-Al+4Cl-Al(Cl)4-2AlCl4-+6H2O 2Al(OH)3+6H+8Cl-18Institute of MicroelectronicsInstitute of Microelectronics键合丝的要求表面洁净光滑长丝、单层、单根密绕严格包装和储存10-15C,20-50%RH419Institute of Microelectronics提高键合可靠性无论何种键合，键合表面特性是至关重要的。洁净度（等离子体清洗）表面粗糙度表面镀层的厚度阻挡层的应用TiW高质量的键合丝可靠的键合工艺等离子体清洗20Institute of Micr

7、oelectronics21Institute of Microelectronics模塑料22Institute of Microelectronics模塑的基本工艺模塑料通常为热固性塑料热固性：在加热固化后不会再次受热软化热塑性：在加热塑化后如果再次受热还会再次软化23Institute of Microelectronics24Institute of Microelectronics模塑料的基本构成基体（10-30%）（高分子化合物树脂）环氧树脂硅酮树脂1,2-聚丁二烯酯树脂添加剂（60-90%）固化剂催化剂填充剂（SiO2）阻燃剂脱模剂染色剂525树脂特性讲义2726主要生产厂家日本

8、住友日东日立化成美国PlaskonHysol(Cookson)中国中科院化学所27Institute of Microelectronics性能检测与相关标准讲义3828Institute of Microelectronics模塑料的类型（p.32）普通型快速固化型无后固化型高热导型低应力型低辐射型低膨胀型低翘曲型29Institute of MicroelectronicsInstitute of Microelectronics普通型模塑料结晶二氧化硅型热导率高、线膨胀系数大、成本低分立器件、LSI熔融二氧化硅型线膨胀系数小、热导率低、成本较高VLSI、大尺寸分立器件30Institut

9、e of MicroelectronicsInstitute of Microelectronics低应力型模塑料固化过程产生的收缩应力温度变化时的热应力热应力导致失效开裂温度变化时的热应力弹性模量线膨胀系数玻璃化转变温度631Institute of Microelectronics考核与命名讲义40-4232Institute of Microelectronics模塑料的发展模塑料随微电子技术和封装技术而发展WHY?高纯度低应力低辐射33引线框架材料34引线框架的功能电连接对内依靠键合实现芯片与外界的信号连接依靠焊点与电路板连接机械支撑和保护对芯片起到支持与外壳或模塑料实现保护散热散热通

10、道35Institute of MicroelectronicsInstitute of Microelectronics不同封装的引线框架陶瓷封装和塑料封装（没有金属封装？）36Institute of MicroelectronicsInstitute of Microelectronics引线框架材料的要求热匹配良好的机械性能导热性能好使用过程无相变材料中杂质少低价加工特性和二次性能好材料优点缺点使用场所Kovar合金Fe-29Ni-17Co1.机械强度高2.与非金属材料匹配好3.耐腐蚀性好1.价格昂贵陶瓷封装金属底座与封装环42合金Fe-42Ni1.机械强度高与非金属材料匹配好1.抗弯

11、强度稍差2.导热性差陶瓷封装塑料封装铜合金1.导热性能高2.电镀性能好3.低价1.机械强度低2.线膨胀系数较高塑料封装4J294J42194 Alloy2抗弯强度(kg/mm )536545软化温度(C)-650400熔点(C)145014271090-6线膨胀系数(10 /C,20-350C)4.5-5.54.4-5.616.3导热系数(W/cmC)0.190.152.63导电率(%IACS)43652弹性模量(kg/mm )1340015000120003比重（g/cm ）8.178.128.97常见引线框架材料及应用引线框架材料的主要物理性能3739384041Institute of

12、MicroelectronicsInstitute of MicroelectronicsKovar合金Kovar合金（4J29）属于定膨胀合金Co带材与丝材去应力退火线膨胀系数与陶瓷、玻璃匹配Institute of Microelectronics铜合金导电特性好引入第二相弥散强化，提高强度常用有Cu-Fe-P，Cu-Cr，Cu-Zn，Cu-Zr等等机械加工性能好热膨胀系数与塑料封装匹配42Institute of MicroelectronicsInstitute of Microelectronics42 Alloy具有与Kovar合金类似性能的框架材料（封接材料）采用Ni的添加取代C

13、o去应力退火线膨胀系数与Kovar合金相近Institute of Microelectronics引线框架的成型冲压型蚀刻型843Institute of Microelectronics表面处理表面电镀Ni/AuAgSn or Solder铜引线的预氧化44Institute of Microelectronics引线框架的质量标准引线键合区几何尺寸、表面涂敷、引线扭曲、平整度、共面性芯片粘接区几何尺寸、表面涂敷、粗糙度45芯片粘接材料46芯片粘接的基本概念Chip Attachment/Bonding，通常采用粘接技术实现管芯（IC Chip）与底座（Chip Carrier）的连接机械

14、强度、化学性能稳定、导电、导热、热匹配、低固化温度、可操作性47Institute of MicroelectronicsInstitute of Microelectronics几种基本的芯片键合类型银浆粘接技术低熔点玻璃粘接技术导电胶粘接技术环氧树脂粘接技术共晶焊技术48Institute of MicroelectronicsInstitute of Microelectronics环氧树脂粘接技术工艺简单、成本低廉适合于大规模生产，质量上已经接近Au-Si共晶焊水平可以分为两类：导电、导热胶“导电胶”导热、电绝缘胶949Institute of Microelectronics导电胶粘

15、接技术环氧树脂粘接剂金属粉粒（银）减少欧姆接触改善导热性50Institute of Microelectronics固化条件一般固化温度在150C左右，固化时间约1hr固化前：“导电胶”不导电固化后：溶剂挥发、银粉相互紧密接触形成导电链封装基板与外壳材料基板材料的性能电介电常数、功耗、电阻、热热导率、热膨胀系数、热稳定性、物理表面平整度、表面光洁度化学化学稳定、低孔隙率、高纯度5153Institute of Microelectronics氧化铝（Al2O3）陶瓷良好的介电性能、高的机械强度、高热稳定性、高化学稳定性应用最广90-99%Al2O3性能与Al2O3含量相关添加剂（黑色、紫色、

16、棕色）瓷Institute of Microelectronics5254Institute of Microelectronics其它陶瓷基板材料氧化铍（BeO）热导率8倍于氧化铝，用于功率器件贵毒氮化铝（AlN）高热导率，用于替代氧化铍与Si相近的热膨胀系数低价（与氧化铍比较）Institute of MicroelectronicsMCM-LMCM-CMCM-DMCM-D/CMCM-Si高密度压合PCB共烧陶瓷 硅、陶瓷上的薄膜共烧陶瓷上的薄膜硅上绝缘层工艺性好很好有限有限有限成本中中高高高金属层数 15505505导线间距 100-150250-45025-7550-7525I/O面面

17、周边面周边散热弱很弱好很弱好介电常数 3.0-3.59.73.03.03.5热导率（W/mC）CTE（ppm/C）介电常数（1MHz）拉伸强度（M Pa）Al2O315-334.3-7.44.5-10与含量相关BeO150-3006.3-7.56.7-8.9230AlN82-3204.3-4.78.5-10-滑石2.1-2.58.6-10.55.5-.7.555.2-69.0镁橄榄石2.1-4.2116.255.2-69.01055其它陶瓷基板材料滑石和镁橄榄石用于厚膜电路低介电常数低强度低价玻璃、石英、蓝宝石56主要陶瓷基板材料基本性能57Institute of Microelectron

18、ics多层陶瓷基板材料HTCCHigh Temperature CofiredCeramic1500CMo-Mn or W as the metallizationLTCCLow Temperature CofiredCeramic850-900CAg-Pd,Au,Ag or CuHigher wiring density58Institute of MicroelectronicsProcess flow of LTCC59Institute of MicroelectronicsInstitute of MicroelectronicsMCM高密度基板材料60Institute of Mi

19、croelectronicsInstitute of Microelectronics金属底座与外壳材料金属封装的特点是：散热好、气密性好、机械强度高。CuMoCuWWSteel and Stainless SteelKovar and 4J50热导率（W/mC）CTE（ppm/C）电阻率（m）拉伸强度（M Pa）Mo15-334.3-7.4-8(4.9-5.2)1065510Cu90W150-3006.3-7.5-86.610489.5W82-3204.3-4.7-8(4.8-5.5)10310-1517Kovar2.1-2.58.6-10.5-85010522-552钎焊熔焊压焊 其它应用

20、范围 引线焊接芯片焊接外壳封接外壳制造引线焊接外壳封接外壳制造引线焊接 芯片粘接外壳封接 外壳制造116162金属底座材料基本性能焊接材料63Institute of MicroelectronicsInstitute of Microelectronics微电子封装中的焊接64Institute of MicroelectronicsInstitute of Microelectronics钎焊技术软钎焊（450C）Sn-Pb低温焊料硬钎焊65Institute of Microelectronics焊料的基本组成焊接合金（金属）溶剂助焊剂 Soldering is the bonding

21、of metallic surfaces via anintermetallic alloy.The Intermetallic bond is created by a diffusionprocess.Soldering is an interaction between heat delivery,flux chemistry,and solder chemistry.HeatSolderFlux66Institute of MicroelectronicsSn-Pb共晶再流焊1267Institute of Microelectronics63Sn-37Pb68Institute of

22、 MicroelectronicsChipIMCNi/AuUBMLead rich layerFlip chip bondingEutectic Pb-SnEutectic Pb-SnIMCNi3P69Objective of Green Industry70Lead Consumption in Industry71Institute of MicroelectronicsInstitute of MicroelectronicsHistory of Lead Free72Institute of MicroelectronicsInstitute of MicroelectronicsLe

23、ad Free in Europe The primary drivers for lead are thought to be fromEurope and Japan.The proposal is entitled the Waste Electrical and ElectronicEquipment(WEEE)Directive.Prevention:the use of lead as well as several other toxicmaterials should be phased out by January 1,2004.Separate Collection:ens

24、ure that new products offer a“take-back”recycling to private households as well as other holdersfree of charge.Treatment:treatment of waste from electrical and electronicequipment.Recovery:ensure producers are setup to re-use and recycle acertain percentage of the waste from electrical and electroni

25、cequipment depending on the product ICER.1373Institute of MicroelectronicsLead Free in JapanThere is currently no federal legislation in Japan directed towardsbanning the use of lead in electronics.The Japanese Home Electronics Recycling Law requires OEMs tocollect and recycle four major products by

26、 April 1,2001.Althoughlead was not specifically mentioned,the Japanese EPA and thegovernment suggest reducing the use of lead as part of theirincreased recycling initiatives.The Japanese Ministry of International Trade and Industry(MITI)has recommended that the use of lead be reduced by half by they

27、ear 2000 and by two-thirds by 2005.The Japan Institute for Electronic Packaging(JIEP)recommendsmass production using Pb-free solder during 1999-2000,full scalerecycling of assembly boards by 2001-2002,adoption of Pb-freesolders in reflow soldering processes by 2001,Pb-containing solderused only exce

28、ptionally by 2005-2010,and complete eliminationof Pb solder by 2010-2015.74Institute of MicroelectronicsCriteria for Lead Free SolderNo negative environmental impact now or in thefutureSufficient quantities of the elementsLow costSimilar melting temperature to that of Sn-Pb soldersEutectic Sn63-Pb37

29、(183C)Physical properties,Fatigue resistanceAdequate wettabilityCompatibility with existing parts and processesIdeally available in all forms i.e.bar,paste and wireAdequate shelf life and performance75JEDECJEIDAEUELVD 0.2wt%Pb 0.1wt%Pb85wt%Pb are exempted!无铅的定义At present,there is no common world sta

30、ndard for thestipulation of the lead content as impurities to lead-freesolders(i.e.,maximum concentration values).However,76Currently,SnPb solders(MP 183oC)For lead-free soldering,SnAgCu solders(MP 217oC)Thus,the components and PCB will be subjected to muchhigher temperatures during leadfree solderi

31、ng and theirreliability is of great concern!无铅带来的工艺问题For Lead-Free,Besides Marketing,What is the Most Technical Concern?77Institute of MicroelectronicsInstitute of MicroelectronicsLead free reflow profileTime is flexibleSoak ZoneRamp from 170-200CTypically 60 90 secsPreheat ZoneRamp below 4C/SecRamp

32、 ZoneFrom 200C to reflowReflow Zone225-235CTime above reflow 30-60secspeak in 60 90 SecsTimeProcess Window is NarrowerCooling to 125C78Institute of MicroelectronicsInstitute of MicroelectronicsSome Lead Free Solder AlloysAlloy SystemCompositionMelting RangeSn-Pb60Sn-40Pb183-188Sn-CuSn-0.7Cu227Sn-Ag-BiSn-3.5Ag-3Bi206-213Sn-Ag-CuSn-3.8Ag-0.7Cu217Sn-AgSn-3.5Ag2211479Institute of MicroelectronicsMelting Points of Solder Alloys80Institute of MicroelectronicsSn-Ag-Cu81Institute of MicroelectronicsGreen Electronics Not only Lead Free But also halogen free(substrate,adhesive,package,)