BGA封装学习教案

1、会计学1BGA封装封装ChipPR openingChipElectroplated solder bumpMushrooming2. Sputter Under Bump Metal金属层溅射金属层溅射3. Coat with PR覆盖光胶覆盖光胶4. Pattern for bump凸点光刻凸点光刻5. Electroplating Cu and Sn/Pb焊料电镀焊料电镀6. Remove Resist去除光胶去除光胶1. Wafer with Al pad钝化和金属化晶片钝化和金属化晶片ChipPassivationAl contact padChipUBMChipThick phot

2、oresist filmChip7. Strip Under Bump Metal去除去除UBMChip8. Reflow回流回流 Chipsolder ball after reflow第1页/共21页Electroplating Solder Bumping Process电镀凸点制备工艺电镀凸点制备工艺Peripheral array solder bumps 周边分布凸点Area array solder bumps 面分布凸点 The peak temperature of reflow process回流焊峰值温度： 220 C. The effective bump pitch

3、for peripheral array周边分布有效凸点间距： 125 m.第2页/共21页Photoresist Thickness 光刻胶厚度光刻胶厚度: 40100 mBump Material凸点材料凸点材料: 63Sn/37PbBump height 凸点高度凸点高度: 75140 mUBM layer凸点下金属层凸点下金属层: Ti/W-Cu, Cr-Cu Min. effective pitch of bump 最小有效凸点间距最小有效凸点间距 : 125 mI/O array输入输入/ /输出分布输出分布: peripheral array周边分布周边分布 and area a

4、rray面分布面分布第3页/共21页Samples with Different Dimensions PCB上不同尺寸倒装焊样品Flip Chip on Flexible substrate在软质底板上倒装焊Direct chip attach on low-cost PCB, flexible substrate 已完成在低成本PCB和软质底板上倒装焊工艺的研究MCM-L technology 多芯片组装技术.第4页/共21页第5页/共21页ChipSolder BumpElectroless Ni/AuPassivation第6页/共21页Process flow of Stencil

5、Printing Process丝网印刷工艺流程(not to scale)Wafer preparation晶片制备(Passivation and Al pads)Zincation Pretreatment锌化预处理Electroless Ni/Immersion Au化学镀镍/金Stencil Printing丝网印刷Solder Reflow and Cleaning焊料回流和清洗第7页/共21页Electroless Ni/Au Stud (Cross section)化学镀镍化学镀镍/金金Solder Paste Printing浆浆料印刷料印刷Reflow回流回流第8页/共21

6、页第9页/共21页Flip Chip on PCB for Testing在PCB上倒装焊测试样品第10页/共21页第11页/共21页Test Dice 测试芯片Reliability Test (Thermal Cycling)可靠性测试Mechanical Properties Test (Bump shear)机械测试Low cost substrate低成本底板Bumping凸点制备Assembly (Bonding and Underfilling)装配工艺第12页/共21页Thermal CyclingTemperature & HumidityHigh temperatu

7、re StorageMultiple ReflowsNo failure after 1500 cyclesNo degradation after 1000 hours No degradation after 10 reflowsStencil Printing Flip ChipElectroplating Flip ChipPass 1000 cycles -40 C+125 C1cycle/hrJESD22-A104-BNo degradation after 100 hours 120 C and 85%RHNo degradation after 1000 hours150 C,

8、 AirJESD22-A103-ANormal Reflow ProfileResultsConditionStandard第13页/共21页第14页/共21页第15页/共21页PeripheralArea Array 第16页/共21页5mUBM (Ni)5mBCB_20.5m/5mMetal_2(Ti-W/Cu)5mBCB_1Key Feature :Silicon substrateBCB2Metal 2UBMAl pad120m80m100m120m250m300mPassivationSolder ballBCB1Critical Dimension :500mSolder ball

9、 pitch 300mSolder ball size (diameter)第17页/共21页Wafer startMetal1 Al SputteringPhotolithographyWet etchPassivation PE-CVD SiO2PhotolithographyPlasma dry etchBCB 1Spin coatingPhotolithographyHard CureMetal 2Al sputteringPhotolithographyWet etchBCB 2 Spin coatingPhotolithographyHard CureMetal 2Ti-W/Cu seed s