【摘要】：焊點作為連接芯片與基板的介質(zhì),在電子封裝中扮演著至關(guān)重要的角色,在微電子產(chǎn)品的正常工作中,焊點在高溫和負載的交互作用下,一方面起到傳輸物理信號的作用,同時還提供著機械保護和熱傳導的作用。焊點內(nèi)各材料的熱膨脹系數(shù)不匹配,極易在體釬料/IMC界面處產(chǎn)生結(jié)構(gòu)缺陷并誘發(fā)熱疲勞裂紋的萌生及擴展,最終導致焊點以剪切斷裂的形式失效。因此,研究焊點的剪切力學行為顯得尤為迫切。采用試驗的方法對Sn-3.0Ag-0.5Cu、Sn-0.3Ag-0.7Cu、Sn-0.3Ag-0.7Cu-0.07La和Sn-0.3Ag-0.7Cu-0.07La-0.05Ce焊點施加剪切載荷,旨在研究加載速率(0.01mm/s、0.05 mm/s、0.5 mm/s、1 mm/s和2 mm/s)、焊點尺寸(500μm、700μm和900μm)、焊盤成分(Cu/SAC/Cu和Ni/SAC/Ni板級結(jié)構(gòu))和回流組裝順序(Cu/SAC/Ni和Ni/SAC/Cu板級結(jié)構(gòu))以及時效處理(160℃下時效0天、10天、20天、30天和40天)對BGA板級結(jié)構(gòu)焊點力學性能的影響規(guī)律,研究表明:四種單界面焊點的剪切強度和至斷位移均大于板級結(jié)構(gòu)中的焊點,板級結(jié)構(gòu)中添加稀土元素的低銀焊點剪切力學性能得到了很大的改善,基本與高銀焊點的剪切強度相當,尤其是Cu/SAC0307-0.07La-0.05Ce/Cu焊點的剪切強度表現(xiàn)更為突出。單板結(jié)構(gòu)中焊點斷裂在體釬料上,而板級結(jié)構(gòu)中焊點斷裂在體釬料/IMC的界面處。板級結(jié)構(gòu)中剪切斷裂與實際工況更為相近,斷口形貌充分反應(yīng)出其斷裂機理。在Cu/SAC/Cu板級結(jié)構(gòu)中,高銀焊點的剪切強度隨著加載速率的增加呈現(xiàn)先增加后降低的變化趨勢,另外三種焊點剪切強度持續(xù)增加。至斷位移均隨加載速率的增加而降低,但高銀焊點降幅較大。加載速率由低速向高速轉(zhuǎn)變時,高銀焊點的斷裂位置由體釬料/IMC處向IMC轉(zhuǎn)變;低銀焊點的斷裂位置則由體釬料向體釬料/IMC處轉(zhuǎn)變;加入稀土元素的低銀焊點的斷裂位置僅是在體釬料上向IMC方向上發(fā)生了一定的偏移。隨著焊點尺寸的減小,焊點的剪切強度逐漸增加,至斷位移逐漸減小,剪切應(yīng)變則呈現(xiàn)先增加后降低的變化趨勢,斷裂位置向體釬料轉(zhuǎn)移。Ni/SAC/Ni板級結(jié)構(gòu)焊點的剪切強度和至斷位移均大于Cu/SAC/Cu板級結(jié)構(gòu)焊點。Cu/SAC/Cu板級結(jié)構(gòu)焊點斷裂在體釬料/IMC界面處,Ni/SAC/Ni板級結(jié)構(gòu)焊點斷裂位置均發(fā)生在體釬料上。Cu/SAC/Ni結(jié)構(gòu)中的剪切強度和至斷位移均低于Ni/SAC/Cu板級結(jié)構(gòu)。對于Cu/SAC/Ni板級結(jié)構(gòu)焊點均斷在Cu/SAC側(cè);對于Ni/SAC/Cu板級結(jié)構(gòu)焊點基本斷在Ni/SAC側(cè)。Cu/SAC/Cu和Ni/SAC/Ni板級結(jié)構(gòu)焊點的剪切強度和至斷位移均隨時效時間的延長而降低,但Cu/SAC/Cu焊點的下降速率大于Ni/SAC/Ni焊點。在時效初期兩種結(jié)構(gòu)中焊點的剪切強度均出現(xiàn)了大幅降低。此外,在兩種結(jié)構(gòu)中,加入稀土元素的低銀焊點的抗時效能力優(yōu)于高銀焊點,表現(xiàn)出良好的剪切力學性能,尤其是Ni/SAC0307-0.07La-0.05Ce/Ni焊點的力學行為表現(xiàn)更為明顯。
[Abstract]:Solder joint, as the medium connecting chip and substrate, plays an important role in electronic packaging. In the normal operation of microelectronic products, solder joint plays the role of transmitting physical signal under the interaction of high temperature and load. It also provides mechanical protection and heat conduction. Because of the mismatch of thermal expansion coefficient in solder joints, structural defects can easily occur at the interface of solder / IMC, and the initiation and propagation of thermal fatigue cracks will lead to the failure of solder joints in the form of shear fracture. Therefore, it is urgent to study the shear mechanical behavior of solder joints. Shear loads were applied to Sn-3.0 Ag-0.5CuN Sn-0.3Ag-0.7CuN Sn-0.3Ag-0.7Cu-0.07La and Sn-0.3Ag-0.7Cu-0.07La-0.05Ce solder joints. The aim of this study was to study loading rate (0.01mm / s 0.05mm / s) 0.5 mm / s (1 mm/s and 2 mm/s), solder joint size (500 渭 m, 700 渭 m and 900 渭 m), pad composition (Cu/SAC/Cu and Ni/SAC/Ni plate-grade structure), reflow assembly sequence (Cu/SAC/Ni and Ni/SAC/Cu plate-grade structure) and aging treatment (160 鈩，

本文編號：2164630