Effect of the Ni/Pd/Au-Cu pre-plated finish lead frame surface structure treated by various surface roughening methods on packaging properties

Two roughening methods involving micro-etching and mixed mode etching of pre-plated finish (PPF) surfaces were used to examine the nickel-coated layer thickness effect on the surface morphology. The PPF lead frames treated by micro-etching (ME) surface roughness drastically decreased with increased nickel-coated layer thickness, while the PPF lead frames treated by mix mode roughening (MMR) maintained comparatively good surface roughness even with thick nickel-coated layers. The shear strength of the PPF of a lead frame treated by ME and MMR reached up to five times that of the untreated PPF based on a moisture sensitivity level button shear test. The failure mechanism of the PPF lead frame treated by ME was the formation of cracks through the interface between the lead frame and the epoxy molding compound, which led to the breakage. An experimental basis is provided for the application of PPF lead frames, as well as a theoretical foundation for increasing the adhesion strength of rough surfaces. Therefore, this study is of great theoretical and practical significance.     

ABS塑料小件化学镀银及银层氯化的研制

在H2SO4/H2O2混合液中对ABS塑料进行表面粗化,然后进行化学镀银,再用FeCl3溶液氯化镀银层,制备出心电图仪(ECG)用一次性Ag/AgCl电极。研究了活化时间和装载量对化学镀银增重及电阻的影响。采用扫描电镜(SEM)和X射线衍射(XRD)技术分析了镀层的表面形貌和物相组成,分别用四探针法和冷热循环法测试了镀层表面的方块电阻及镀层与基体的结合力。结果表明,粗化处理后的ABS塑料表面粗糙度增大,亲水性增加。适宜的活化时间和化学镀银装载量分别为5 min和80 cm2/L。此条件下制备的化学镀银层均匀致密,与基体的结合力强。氯化前后镀银层的导电性均良好,表面方块电阻分别为30 mΩ/□和53.6 mΩ/□。测得Ag/AgCl心电电极的交流阻抗≤3 kΩ,直流失调电压≤100 mV,内部噪音≤150μV,模拟除颤恢复≤3 kΩ,偏置电流耐受度≤100 mV,符合国家医药行业YY/T 0196–2005标准。     

Electroplating onto inorganic glass surfaces - Part II: Mechanical treatment to improve adhesion‡

The metallization of glass surfaces was carried out using chemical and mechanical methods to achieve a roughened surface. Comparable to ABS polymers, where chemical treatment resulted in a selective etching of the chemically weaker phase and the adhesion mechanism was due to mechanical keying of the metal into the etched caverns, a finely structured glass surface must be properly prepared to ensure metal anchoring. For chemical treatment, melts of sodium and potassium hydroxide and potassium hydrogen sulfate were used. The treatment did not result in a finely roughened surface structure and no improvement in adhesion could be achieved. A mechanical treatment (using abrasive blast with Al₂O₃ of various grain sizes) produced a uniformly roughened glass surface but only with a combination of mechanical and chemical treatment, crevices comparable to the caverns produced in ABS-electroplating were attained. For chemical treatment, solutions of ammonium hydrogen fluoride of various concentrations were used. Soda-lime glass could be etched more easily than the borosilicate glass and gave higher peel-strengths.     

Characteristics of surface roughening during plane strain compression of polycrystalline iron

Roughening behavior of the free surface of polycrystalline iron during plane strain compression is investigated experimentally. The changes in the shape of the free surface, which is roughened during plastic deformation, are observed in the three-dimensions. It is found that the mountains and the valleys of the roughened shape tend to elongate in the constrained direction for the specimen with isotropic grain shape. The shapes of the roughness curves in the loading direction and in the constrained direction are compared. The normalized height distribution of the roughness curve in the constrained direction is symmetric, while that of the roughness curve in the loading direction is asymmetric and positively skew during plane strain compression. Based on a simple simulation of the roughness curves by a random midpoint displacement method, this difference is supposed to be caused by the constraint of the material flow under plane strain condition.     

环氧树脂灌封器件电镀前处理工艺改进

针对环氧灌封器件表面镀层结合力差的问题,在镀前对环氧树脂灌封体进行喷砂,并将铬酸酐?硫酸体系化学粗化改为等离子粗化.采用改进的前处理工艺后,环氧树脂灌封体表面的镀层厚度、结合力及可靠性均满足宇航型号产品的使用要求.     

An interpretation of the failure paths of roughened metal/polymerinterfaces

Roughening of metal surfaces enhances the adhesion strength of metal to polymer by mechanical interlocking and this often produces cohesive failure. In a previous work [1], an adhesion study on a roughened metalpolymer system was carried out, and the correlation between adhesion strength and failure path was investigated. In the present work, the correlation between failure path and microstructure of metal surfaces before molding was studied. The results showed that the variation in failure path could be explained by introducing a simple adhesion model developed from the theory of the fiber reinforcement of composite materials. It is believed that this model can be extended to other similarly roughened metal-polymer systems.     

Real-time stress evolution during Si1-xGex Heteroepitaxy: Dislocations, islanding, and segregation

We have used sensitive real-time measurements of film stress during Si_1-xGe_x molecular beam epitaxy to examine strain relaxation due to coherent island formation, and to probe the kinetics of Ge surface segregation. We first describe our novel curvature-measurement technique for real-time stress determination. Measurements of the relaxation kinetics during high temperature Si₇₉Ge₂₁ growth on Si (001) are reported in which formation of highly regular arrays of [501]-faceted islands produce 20% stress relaxation. An island shape transition is also observed that reduces the effective stress by up to 50% without dislocations. Nonuniform composition profiles due to Ge surface segregation during growth of planar alloy films are determined with submonolayer thickness resolution from the real-time stress evolution. Up to two monolayers of Ge can segregate to the growth surface.     

Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal phase: growth kinetics analysis

The morphology and lateral growth rate of isotactic polybutene-1 (it-PB1) have been investigated for crystallization from the melt over a wide range of crystallization temperatures from 50 to 110°C. The morphology of it-PB1 crystals is a rounded shape at crystallization temperatures lower than 85°C, while lamellar single crystals possess faceted morphology at higher crystallization temperatures. The kinetic roughening transition occurs around 85°C. The nucleation and growth mechanism for crystallization does not work below 85°C, since the growth face is rough. However, the growth rate shows the supercooling dependence derived from the nucleation and growth mechanism. The nucleation theory seems still to work even for rough surface growth. Possible mechanisms for the crystal growth of this polymer are discussed.     

Effective surface roughening of three-dimensional copper foam via sulfurization treatment as a bifunctional electrocatalyst for water splitting

Cost effective electrocatalysts in water splitting reaction are critically important for the practical application of hydrogen fuel. The surface of three-dimensional copper foam is successfully roughened via one-step sulfurization reaction, and cuprous sulfide is formed on copper foam accordingly, which is denoted as Cu₂S@Cu. The as-prepared Cu₂S@Cu electrocatalyst exhibits remarkable performance on oxygen evolution reaction in basic solution, with a low overpotential of 345 mV to achieve 20 mA cm⁻². Cu₂S@Cu also shows enhanced performance on hydrogen production, compared to the original copper foam. Furthermore, Cu₂S@Cu can work as both cathode and anode in full water splitting, with superior activity to the noble metal-based electrocatalysts under large current densities. This study demonstrates that surface roughening technique on copper foam by sulfurization reaction can be valuable for developing novel copper-based electrocatalysts for water splitting.     

GaP表面粗化对AlGaInP发光二极管光电特性的影响

采用湿法溶液粗化AlGaInP基红光LED表面GaP层 ,并在粗化后的GaP表面沉积ITO,研究了粗化时间对GaP表面形貌的影响,并利用SEM、半导 体 芯片测试机、X射线衍射仪、X射线光电子能谱对LED器件表面形貌、光电特性曲 线、界面晶向、元素特性进行表征,比较了粗化前后的LED亮度和光电特性变 化。测试结果表明:采用HIO₄、I₂、HNO₃系列粗化液在室温、粗化时间为30 S 时,有效增加了光在通过GaP面与ITO界面时的出光角度,使AlGaInP发光二极管 的发光效率提高21.4%,同时引起界面处的缺陷密度升高,费米能级 远离价带,主波长蓝移0.36 nm,正向电压上升0.04 V。