(西北工業(yè)大學(xué) 材料學(xué)院 凝固技術(shù)國家重點(diǎn)實(shí)驗(yàn)室，西安710072)
摘 要: Hg3In2Te6(MIT)晶體是一種新型的短波紅外光電探測材料，采用熱壓超聲球焊的方法實(shí)現(xiàn)MIT紅外探測器與外電路的引線連接，探討MIT復(fù)合電極厚度及結(jié)構(gòu)對(duì)鍵合率的影響規(guī)律，研究超聲功率和鍵合壓力對(duì)第一焊點(diǎn)的外觀形貌和鍵合強(qiáng)度的影響機(jī)理。結(jié)果表明：在化學(xué)拋光后的MIT晶片表面蒸鍍0.2 μm In、1.0 μm Au制備In/Au復(fù)合電極時(shí)，鍵合率顯著提高，達(dá)到100%；MIT與In/Au復(fù)合電極間存在一定的互擴(kuò)散，促進(jìn)了鍵合過程的形成；超聲功率與鍵合壓力對(duì)焊點(diǎn)形貌和鍵合強(qiáng)度影響最大，當(dāng)超聲功率為0.45~0.55 W、鍵合壓力為0.5~0.6 N時(shí)，焊球與引線的直徑比約為3.5，焊點(diǎn)變形適中，有效鍵合面積較大，90%以上的斷裂發(fā)生在引線位置，表明此種工藝參數(shù)下形成的鍵合強(qiáng)度高、可靠性好。
關(guān)鍵字: Hg3In2Te6芯片；熱壓超聲鍵合；Au 電極；In中間層
（Northwestern Polytechnical University, School of Materials Science and Engineering,
State Key Laboratory of Solidification Processing, Xi’an 710072, China）
Abstract:In order to realize the connection of Hg3In2Te6 (short for MIT), a new type of near-infrared photoelectric material, with outer circuits, the thermo-sonic bonding technology between MIT electrode and down-lead wire was used, and the influence of the electrode thickness and structure on the bonding ratio was studied. Furthermore, the effects of ultrasonic power and bonding pressure on the first joint morphology and bonding strength were also analyzed. The results show that the bonding rate increases (reaching 100%) when 0.2 μm In interlayer was inserted between MIT wafer after chemical polish and the Au electrode with thickness of 1 μm. XPS analysis results show that inter-diffusion between MIT and In/Au composite electrode promotes the bonding process. The welding ball morphology and bonding quality are mainly affected by the ultrasonic power and bonding pressure. When the ultrasonic power and the bonding pressure are about 0.45-0.55 W and 0.5-0.6 N, respectively, the diameter ratio between the ball and wire is about 3.5, and more than 90 % failure position occurs at wire by tensile test, indicating the perfect shape of welding ball and good bonding strength and reliability can be reached.
Key words: Hg3In2Te6 chip; thermo-sonic bonding; Au electrode; In interlayer
