印制电路铅锡镀层的退除方法

前言在印制电路板(PCB)制造过程中,常常遇到退除铅锡镀层的问题.如插头镀金时,需将插头部位的铅锡镀层退除,以便在露出的铜层上镀镍、镀硬金.最近在欧美市场上流行的裸铜上复盖阻焊膜,或称裸铜上黑化后复盖阻焊膜,即SMOBC工艺,需要在图形电镀蚀刻后,再去掉电镀的铅锡合金,成为裸铜的印制电路,以防止波峰焊接时阻焊膜皱裂的现象发生.有时,要脱除PCB上的毛刺或整块不要的镀层,都需要采用退除工艺.国内普遍采用氟化氢铵溶液退除铅锡镀层.但此种溶液在组成含量控制不当,如氟化氢铵含量偏低,或过氧化氢偏高时,均对层压板有严重的腐蚀作用.氟化氢铵本身易潮解,系无机有毒品,在PCB生产中逐渐被其它药剂所取代.现将有关先进退镀方法评述如下:     

电镀挂具退镀液的研究进展

结合电镀挂具的结构特点,从金属镀层退除的化学基础、退镀原理、现有退镀工艺等方面对目前国内外退镀液的研究与应用现状进行综述,指出退镀液的发展方向.     

热风整平助焊剂的研制

以两性表面活性剂(自制)、光亮剂、消烟剂、活化剂及混合溶剂为原料,配制热风整平助焊剂。探讨组分配比对241~243℃热风整平后印制板焊盘、孔涂铅锡的光亮度、饱满度、红孔及烟大小等的影响。结果表明,助焊剂的最佳组成为两性表面活性剂65%,光亮剂6.5%,消烟剂0.9%,活化剂0.75%,其余为溶剂。焊盘、孔铅锡光亮、饱满、无红孔、烟小,达到印制电路板生产要求。     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。     

废退锡液的循环利用技术研究进展

本文分析了目前常用技术处理废退锡液的优缺点,指出发展废退锡液循环利用技术的重要意义,并综述了该处理技术的研究进展。     

遮蔽型挠性印制电路板保护胶带的研制

通过溶液聚合法得到三种初黏性、剥离强度和持黏性各不相同的丙烯酸酯聚合物。在聚合物中加入交联剂和颜料进行改性后,涂布制成遮蔽型保护胶带,并对其粘合性能进行测试。结果表明三种产品的180°剥离强度分别为1.78,3.06,5.53 N/25mm,可用于开发低黏,中黏,高黏型印刷电路板保护胶黏带。最后考察了不同熟化时间对产品性能的影响。     

NdFeB磁体表面镀铝膜层退镀液配方的研究

用NaOH作腐蚀剂,添加辅助盐、表面活性剂、配位剂和缓蚀剂,研制了一种高效稳定的NdFeB表面镀铝膜退镀液。以Nd Fe B试样表面的铝含量和基体失重量作为性能评定指标,通过正交试验确定了优化的退镀液配方为:NaOH 10 g/L,Na_2CO_3 30 g/L,十二烷基苯磺酸钠6 g/L,EDTA-2Na 4g/L,六次甲基四胺4 g/L。优化的退镀液在室温条件下退镀3 min,即可把NdFeB基体上约12μm厚的铝膜退除干净,而且退镀后基体的剩磁、矫顽力和最大磁能积仅分别变化1.27%、1.25%和0.47%,磁性能损伤较小。探讨了NdFeB表面镀铝膜层的退镀机理。     

JH－1型电镀液净化器研制报告

报道了ＪＨ－１型电镀液净化器以动态吸附方式充分利用吸附剂的吸附性能，并从设计依据、设计要点及试验结果等方面详细介绍了该净化器的研制过程。     

一种去除钛及钛合金微弧氧化膜的碱性退膜液

为了减少钛及钛合金材料表面处理过程中的吸氢和满足清洁生产的要求,研制开发了一种用于去除钛及钛合金微弧阳极氧化膜的碱性退膜液,对这种退膜液的退膜效果和稳定性能进行了研究,并进一步考察了退膜液对钛及钛合金基体的腐蚀性能、退膜后重新微弧氧化的难易以及微弧氧化膜与基体的结合情况。实验表明:该退膜液具有退膜效果好、稳定性能好、不影响上膜及膜层与基体结合的特点,为完善钛及钛合金微弧氧化工艺及其它钛及钛合金阳极氧化膜退膜液的开发提供了有价值的参考。     

Processing of 0.55(Ba0.9Ca0.1)TiO3-0.45Ba(Sn0.2Ti0.8)O3 lead-free ceramics with high piezoelectricity

We report a large piezoelectric constant (d₃₃), 720 pC/N and converse piezoelectric constant (d₃₃^*), 2215 pm/V for 0.55(Ba_0.9Ca_0.1)TiO₃-0.45Ba(Sn_0.2Ti_0.8)O₃ ceramics; the biggest value achieved for lead-free piezoceramics so far. The ceramic powders were calcined between 1050°C-1350°C and sintered at 1480°C. The best properties were obtained at a calcination temperature (CT) of 1350°C. The fitting combination of processing and microstructural parameters for example, initial powder particle size >2 µm, ceramics density ~95%, and grain size ~40 µm led to a formation of orthorhombic-tetragonal-pseudo-cubic (O-T-PC) mixed phase boundary near room temperature, supported by Raman spectra, pointed to the extremely high piezoelectric activity. These conditions significantly increase piezoelectric constants, together with high relative permittivity (ε_r) >5000 and a low loss tangent (tan δ) of 0.029. In addition, the d₃₃ value stabilizes in the range of 400-500 pC/N for all samples calcined between 1050°C and 1250°C. The results entail that the (Ba,Ca)(Sn,Ti)O₃ ceramics are strong contenders to be a substitute for lead-based materials for room temperature applications.     

Preparation and electrochemical performance of uniform RuO2/Ti and RuO2‐IrO2/Ti electrode for electrolysis of NaCl solution

The electrochemical preparation of NaClO has been widely used for the production of industrial disinfectant. To reduce the cost of electrode preparation using the brushing method, this paper introduces a method for the electrodeposition for RuO₂/Ti and RuO₂‐IrO₂/Ti preparation and NaCl solution electrolysis. The deposition of Ir improves the uniformity and stability of the RuO₂/Ti electrode. The optimum preparation conditions and additive concentrations were investigated in detail through the orthogonal experiment. By adjusting the electroplating time, temperature and voltage, the electrode with a high content of available chlorine was synthesized successfully. The physicochemical properties of the as‐prepared RuO₂/Ti and RuO₂‐IrO₂/Ti were determined by XRD, SEM‐EDS, and XPS, and the electrochemical performance and lifetime of the RuO₂/Ti and RuO₂‐IrO₂/Ti was verified via an electrochemical workstation. Uniform and stable RuO₂/TiO₂ and RuO₂‐IrO₂/TiO₂ were synthesized successfully for the electrolysis of the NaCl solution.     

(Ba0.85Ca0.15)(Ti0.90Zr0.06Sn0.04)O3-Fe2O3无铅压电陶瓷的性能研究

采用固相法制备了(Ba0.85Ca0.15) (Ti0.90Zr0.06Sn0.04)O3-xmol％Fe2O3(简写为BCTZS-xFe)无铅压电陶瓷.研究了不同掺杂量对该陶瓷的显微结构、介电、铁电及压电性能的影响.结果表明,所有样品均具有单一的钙钛矿结构,少量掺杂能使晶粒长大,提高电性能.在x=0.025时,具有最佳的综合电性能,压电常数d33 =515 pC/N,机电耦合系数kp=48.2％,机械品质因数Qm =182,2Pr=18.2 μC/cm2,2Ec =4.3 kV/cm,介电常数εr=5175.     

Ti/Al2O3系梯度功能材料研究动态

介绍了目前用于Ti/Al2O3系梯度功能材料制备的几种主要工艺,提出了利用共沉降法制备Ti/Al2O3系梯度功能材料的设想,简述了Ti/Al2O3复合材料制备技术的基础理论及其研究现状,并指出了其不足和未来的发展方向.     

Kinetic investigation of the NO decomposition over V–O–W/Ti(Sn)O2 catalyst

A kinetic study of the NO decomposition over V–O–W/Ti(Sn)O₂ catalyst carried out in a tubular fixed-bed reactor operating under atmospheric pressure at different temperatures and at various space times is presented. Assuming that NO decomposition occurs as a result of electron transfer from the metal active site to antibonding π NO orbital, several kinetic models were derived and applied to describe the kinetics of reaction. The best agreement between the experimental data and theoretical prediction was achieved with the model assuming adsorption of NO on the active sites as the rate-determining step. Finally, it was concluded that V–O–W/Ti(Sn)O₂ catalyst has promising activity for the NO removal in O₂ presence from the effluent gases of the different sources of emission.     

Investigation of ternary system Pb(Sn,Ti)O3-Pb(Mg1/3Nb2/3)O3 with morphotropic phase boundary compositions

(1 − x)Pb(Sn_1−yTi_y)O₃-xPb(Mg_1/3Nb_2/3)O₃ (x = 0.1-0.4, y = 0.45-0.65) ternary system was prepared using two-step columbite precursor method. Phase structure of the synthesized ceramics was studied by using X-ray powder diffraction and the morphotropic phase boundary (MPB) curve of the ternary system was confirmed. The isothermal map of Curie temperature (T_C) in the phase diagram was obtained based on the dielectric-temperature measurements. The coercive field E_C and internal bias field E_i were found to increase with increasing PT content, while decrease with increasing PMN content. The optimum properties were achieved in the MPB composition 0.8Pb(Sn_0.45Ti_0.55)O₃-0.2Pb(Mg_1/3Nb_2/3)O₃, with dielectric permittivity ?_r, piezoelectric coefficient d₃₃, planar electromechanical coupling k_p, mechanical quality factor Q_m and T_C of being on the order of 3040, 530pC/N, 55.5%, 320 and 190 °C, respectively, exhibiting potential usage for high power application.     

Electrochemical corrosion behaviors of Ti3SiC2/Cu composites in a 3.5% NaCl solution

The electrochemical corrosion behaviors of Ti₃SiC₂/Cu composite and polycrystalline Ti₃SiC₂ in a 3.5% NaCl medium were investigated by dynamic potential polarization, potentiostat polarization, and electrochemical impedance spectroscopy. The polycrystalline Ti₃SiC₂ was tested on the identical condition as a control. The characterizations of XRD, X-ray photoelectron spectroscopy, scanning electron microscope, and energy-dispersive spectrometer were used to study the relevant passivation behavior and corrosive mechanism. The self-corrosion current density of Ti₃SiC₂/Cu (6.46 × 10⁻⁶ A/cm²) was slightly higher than that of Ti₃SiC₂ (1.64 × 10⁻⁷ A/cm²). Under open circuit potential, the corrosion resistance of Ti₃SiC₂/Cu was better than that of Ti₃SiC₂. Ti₃SiC₂/Cu exhibited a typical passivation feature with a narrow passivation interval and a breakdown phenomenon. The better corrosion resistance of Ti₃SiC₂ was due to the more stable Si layer of the former. In comparison, for Ti₃SiC₂/Cu composites, Cu reacted with the reactive Si layers in Ti₃SiC₂ to form Cu–Si compounds and TiC, destroying the weak interaction between Si layers and Ti–C layers. In the other hand, the as-formed Cu–Si compounds and TiC dissolved during the corrosion of Ti₃SiC₂/Cu in the 3.5% NaCl medium, causing to the destruction of the passivation film on its surface.     

钛基Pt-Ta电极在离子水生成器中的应用研究

电解离子水具有广泛的用途,可分为碱性水和酸性水。电极是离子水生成器中的核心部件,国外离子水生产器用的电极一般为Pt/Ti电极。为了降低成本,用热分解法制备了Pt-Ta/Ti电极,分析了离子水电极反应原理,用电子显微镜测试了Pt-Ta/Ti电极表面形貌及电极性能。结果表明,Pt-Ta/Ti电极强化寿命和铂含量呈正比,在间歇倒极操作条件下,电解特性满足离子水器使用要求。使用该电极可以生产出性能优异的离子水。     

热压烧结工艺制备Ti2AlC/Ti3AlC2陶瓷材料

以Ti，Al，C为原料，采用热压工艺制备出相组成为Ti2AlC/Ti3AlC2块体材料，合成材料的X—射线衍射和扫描电镜(SEM)分析的结果表明：当烧结温度为1400℃时，材料中的主晶相为Ti2AlC,大小为10μm的板状多晶体；而在1500℃的温度下烧结所得材料的主晶相为Ti3AlC2，其板状多晶体的晶粒尺寸平均约为20μm。