熱壓合瞬間黏著之熱塑型聚亞醯胺的製備及其結構和特性之研究

Abstract

選用多種不同結構之芳香族二胺與二酸酐單體聚合製備一系列取代基種類與官能基位置不同之熱塑型聚亞醯胺(thermoplastic polyimides；TPI)薄膜材料，另以二胺基聚硅烷(a,w-bis(3-aminopropyl) polydimethylsiloxane；APPS)分別與3,3¢,4,4¢-benzophenone tetracarboxylic dianhydride(BTDA)/2,2-bis(4-[3-aminophenoxy]phenyl) sulfone (m-BAPS)製備一系列含不同分子量與含量之APPS的聚硅烷改質聚亞醯胺（poly(imidesiloxane)s；PIS)。模擬LOC (Lead-on-Chip)構裝的製程，TPI或PIS薄膜材料經由高溫瞬間熱壓機於短時間內與引線架基材(如: alloy-42 鎳-鐵合金)直接壓合，同時進行此二材料之間的黏著性能研究。另外亦進行各薄膜材料之玻璃轉移溫度(Tg)、機械性與熱安定性的量測，評估材料的基本特性。採用平衡接觸角量測法評估材料的臨界表面張力(或稱表面能)，進行不同組成之TPI或PIS薄膜材料之表面能對PIS或TPI/alloy-42間界面黏著性的關係研究。針對TPI的溶解度參數與PIS中APPS含量、分子量對PIS之組織形態的影響，與PIS之表面特性與組織形態對其機械性質及其與alloy-42片間之界面黏著力的影響。 胺基位於苯環上之間位(meta-)位置者，相對於位於對位(para-)位置者其TPI材料的Tg值與熱分解溫度較低，而臨界表面張力(gc)與剝離強度則偏高;TPI中之二胺與二酸酐單體的主鏈中同時含有醚基者，其與alloy-42間的結合可獲得較高的剝離強度，BTDA/1,3-bis(3-amino- phenoxy)benzene (m-BAPB)、ODPA/(m-BAPS)及4,4¢-oxydiphthalic anhy- dride(ODPA)/m-BAPB及等三種TPI系統皆具有良好的耐熱性與機械性質，且其與alloy-42之間的剝離強度分別為10.5、12.2、及13.2 N/cm，此強度超過積體電路(IC)封裝的規範標準，10 N/cm。 對pyromellitic dianhydride(PMDA)/p-phenylene diamine(p-PDA)為主基材之PIS而言，當其APPS的分子量Mn分別為507與715克/莫耳且其含量，亦即APPS/PIS莫耳分率，分別為 3 0.5%、0.1%時，即產生相分離。對BTDA/m-BAPS為主基材之PIS而言，當其APPS的分子量分別為996、715與507克/莫耳（分別簡稱為PIS9Siy，PIS7Siy及PIS5Siy；其中的y代表APPS/PIS莫耳分率）且其"y"值分別為 3 0.6%、1.1%與2.7%時，即有相分離的現象產生；而當"y"值分別為 3 7.7%、10.0%與16.6%時，此PIS中富含硅烷之獨立相將會形成一連續性的相。由研究得知APPS分子量較大者，較易產生相分離及APPS-rich的連續相。這些剛剛好形成硅烷連續相之PIS薄膜者，具有明顯的塑性變形行為與最大的延伸率。具有相分離之BTDA/m-BAPS系統的 PIS薄膜具有兩個 Tg點，一個在-118℃ ~ -115℃，另一個在181℃ ~ 244℃之範圍。 PIS薄膜之gc值大小隨APPS的含量與分子量的增加而降低。對同 一PIS薄膜系列而言，其gc與表面矽濃度,[Sisurf],呈線性的反比關係； 在PIS7Siy及PIS5Siy各系列中，其組織形態分別於"y"值等於1.1%與2.7%時，會由均勻相變為非均勻相，使其gc與[Sisurf]之間的關係曲線分別於此"y"值點處產生偏折。而PIS9Siy系列所得的關係曲線則沒有偏折的現象。 Alloy-42片的表面經UV/O3處理後，可改善其表面的潤濕性，提昇PIS薄膜與alloy-42間黏合界面之剝離強度達20%以上。PIS薄膜為同一組成分時，薄膜的流動性顯著地影響黏合界面的黏著強度；當PIS薄膜的組成分不同時，在相同的壓合溫度(400℃)下，薄膜的流動性並非影響界面黏著強度的重要因素。PIS5Si0.6與alloy-42間黏合界面的真正界面黏著力比純BTDA/ m-BAPS聚亞醯胺者高出80%；PIS9Siy與alloy-42間黏合界面的真正界面黏著力則皆為零。潤濕動力學的研究結果顯示，同一系列的PIS（如：PIS5Siy或 PIS9Siy系)中APPS含量愈高者，潤濕活化能愈高，而相分離的形成則具有顯著提昇此活化能的效果。PIS/alloy-42黏合材之PIS剝離膜面的表面形態愈粗糙者，其界面黏著力愈強。

A series of fully aromatic thermoplastic polyimides(TPI) films were prepared with various of aromatic diamine monomers and dianhydride monomers. The relations between the critical surface tension(gc) , glass transition temperature (Tg), thermal properties, adhesive strength and the molecular structure of the TPI were investigated. It is found that the gc of TPI and the peel strength between the TPI film and alloy-42 plate are higher, and the Tg is lower when the amine groups are situated in the meta position as opposed to the para position. As ether linkage is introduced in dianhydride and diamine, the peel strength between the TPI and alloy-42 plate can be improved . The peel strength of 3,3¢,4,4¢-benzophenone tetracarboxylic dianhydride(BTDA)/1,3-bis(3-aminophenoxy)benzene(m-BAPB), ODPA/ 2,2¢-bis (4-[3-aminophenoxy]phenyl)sulfone(m-BAPS), and 4,4¢-oxydiph- thalic anhydride(ODPA)/m-BAPB, is10.5, 12.2, and 13.2 N/cm respectively, which is higher than the requirement of adhesive strength,10 N/cm, between the adhesive tape and leadframe(metal) in integrated circuit(IC) package. Siloxane modified polyimides, called poly(imide siloxane)s,(PISs), were also prepared. The dependence of morphology of the (PISs) on the solubility parameter of unmodified polyimides and the molecular weight and content of a,w-bis(3-aminopropyl)polydimethylsiloxane (APPS) has been studied. The effect of the morphology on the mechanical properties is also under investigation. The domain formation in the PISs with the APPS molecular weight Mn = 507 g/mole is not found until the mole ratio of APPS/PIS 3 0.5% in the pyromellitic dianhydride / p-phenylene diamine (PMDA/p-PDA) based PISs and at mole ratio 3 2.7% in the BTDA/m-BAPS based PISs. As the APPS Mn = 715 g/mole, the critical APPS concentrations of the domain formation in both types of PISs are equal to 0.1% and 1.1%, respectively. The critical concentration is equal to 0.6% in the BTDA/m-BAPS based PIS film with the APPS Mn = 996 g/mole. The isolated siloxane-rich phase in the BTDA/m-BAPS based PISs becomes a continuous phase as the mole ratio of APPS/PIS 3 7.7%, 10.0% and 16.6% as the APPS Mn = 996 g/mole, 715 g/mole, and 507 g/mole, respectively. The effect of surface characteristics and morphology of the PIS film on the true interfacial adhesion between the PIS film and alloy-42 substrate has been studied. The effect of viscosity of PIS film and the surface treatment of UV/ozone ( UV/O3 ) on alloy-42 plates on the peel strength of PIS films/alloy-42 joints is also investigated. The gc of the PIS film decreases with the content and the molecular weight of APPS. The BTDA/m-BAPS based PIS films with the APPS molecular weight Mn = 996 g/mole (PIS9Siy) show two phases in all compositions and linear dependence of the gc on the surface concentration of silicon, [Sisurf], on the PIS films. The PIS film with the APPS Mn = 507 g/mole (PIS5Siy) or Mn = 715g/mole (PIS7Siy) exhibit the morphology change from homogeneous phase to inhomogeneous phase starting at the mole ratio ( y ) of APPS/PIS = 2.7% and 1.1%, respectively. The curves of gc dependence on the [Sisurf] discontinue or deflect at these two compositions respectively. The treatment of UV/O3 on alloy-42 plates improves the wetting on the alloy surface and promotes the peel strength between the PIS films and alloy-42 plates by a magnitude of 3 20%. It shows that the flowability of the same PIS films bonding at different temperatures significantly affects the bonding strength of the joints, but the flowability of different PIS films bonding at the same temperature, e.g. 400℃, is not the key factor governing the bonding strength of the joints. The true interfacial adhesion of the PIS5Si0.6/alloy-42 joint is of 80% higher than that of the unmodified BTDA/m-BAPS based polyimide film/alloy-42 joint. However, zero true interfacial adhesion is obtained between the PIS9Siy films and alloy-42 plates. The wetting kinetics study shows that the higher the siloxane content in the PIS, the higher the activation energy for the adhesive bonding process. And the phase separation significantly increases the activation energy. The scanning electron micrographs of the peeled-off PIS film surfaces from the PIS/alloy-42 joints reveal the rougher surface morphology from the sample with a higher interfacial adhesion.