A peel adhesion study of electroless Cu layers on polymer substrates

The peel adhesion between two different electroless-plated Cu layers and polymer substrates was studied. Cu was electroless-plated onto polymer substrates using two different commercial solutions with different compositions. The adhesion strength between the electroless Cu layers and polymer substrates was measured with the 90° peel test. The adhesion was influenced by the coverage, grain size, and the thickness of the electroless Cu layer. Poor coverage of the electroless Cu layer increased the density of the pores at the interface between the Cu layer and the substrates, thereby degrading the adhesion strength because of a decrease in the contact area. In addition, the electroless Cu layers with larger nodules and larger grains were softer and had higher peel adhesion since the soft and ductile Cu layer promoted a greater amount of plastic deformation during the peel test. This led to enhanced peel adhesion. Finally, as the thickness of the electroless Cu layer increased, the peel adhesion decreased. The thicker Cu layers are not easily bent. Poor bending of the Cu layer induced less plastic deformation, causing a decrease in the peel adhesion. In conclusion, soft and thin electroless Cu layers with greater coverage are preferred in order to obtain good adhesion.     

Improvement in the adhesion between copper metal and polyimide substrate by plasma polymer deposition of cyano compounds onto polyimide

The surface modification of Kapton film by means of plasma polymer deposition is discussed from the viewpoint of improving the adhesion between copper metal and Kapton film substrate. Plasma polymers of AN (acrylonitrile) and FN (fumaronitrile) were used for the surface modification, and the adhesion between the copper metal and the plasma polymer-coated Kapton film was evaluated by the T-peel strength measurement. The surfaces of peeled layers were analyzed by X-ray photoelectron spectroscopy (XPS) and the failure mode is discussed. The plasma polymer deposition of AN and FN shows an effective improvement in the adhesion between the copper metal and Kapton film; in particular, the AN plasma polymer deposition increased the peel strength 4.3 times. Failure occurred mainly in the Kapton film, and the adhesion between the AN plasma polymer and the Kapton film and that between the copper metal and the AN plasma polymer were found to be quite strong.     

Mechanism and evaluation in electroinitiated copolymerization coatings of acrylonitrile and acrylic acid

Adherent films of copolymers on different metal surfaces were formed by an electrolytically initiated polymerization of acrylonitrile (AN) and acrylic acid (AA) in 0.05N H₂SO₄ aqueous solution. The electrolysis was carried out under a constant current. Hydrogen overvoltages for five different metals used as the cathode were measured in order to interpret the nature and quality of the coating. Solutions containing varying volume fractions of AN and containing different electrolytes gave rise to coatings of varying film thickness. Based on the analyses of copolymer compositions, it is believed that the polymer was formed at the cathode by a free-radical propagation mechanism. The film hardness and the adhesion between the polymer and the metal surface were measured with an Arco microknife. Furthermore, the scanning electron microscope (SEM) was used to examine the structure of the film surface and cross section. The corrosion rates of the coated and uncoated metals in substitute ocean water were also measured for purposes of evaluation of the coatings.     

Supercritical fluid‐assisted electroless metal plating onto aramid films: The influence of thermal treatment

Although the production of electro‐conductive aramid fibers is efficient, the method needs to be modified before it can be applied to aramid films. Whereas impregnation of an aramid film with a metal complex using supercritical CO₂ is achievable, the relatively low adhesion strength of the metal layer applied using electroless copper plating is problematic. To solve this problem, thermal treatment was conducted before, after, or both before and after electroless plating. The rationale for using thermal treatment to improve the adhesiveness of the plated layer was based on the findings that (1) an aramid film contains a significant amount of water (about 3.5 % w.o.f.), which might have a negative impact on adhesion; and (2) because an impregnated metal complex liberates metal catalyst by thermal decomposition during impregnation, a supplementary thermal action might liberate more catalyst and thereby improve adhesion. We found that thermal treatment improved adhesion of the metal layer to the aramid film. Moreover, we discovered that with respect to electroless copper plating, a short time‐lag was crucial to obtaining a thin and homogeneous metal layer with strong adhesion. In addition, we demonstrate the affinity of an aramid film for Pd(acac)₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electromagnetic interference shielding effectiveness and mechanical sliding behavior for electroless nickel/phosphorous–poly(tetrafluoroethylene) codeposition on carbon fiber/acrylonitrile–butadiene–styrene composites

Poly(tetrafluoroethylene) (PTFE) powders were mounted on an electroless nickel/phosphorous (Ni/P) film on the surface of a carbon fiber by an electroless codeposition method. This type of carbon fiber filler, denoted FENCF, was then compounded with acrylonitrile–butadiene–styrene (ABS) for use in electromagnetic interference shielding. For the suspension of the PTFE powders, a surfactant was used. Although the adhesion between the electroless Ni/P–PTFE films and the fiber was reduced, the PTFE powders on the surface of FENCF reduced the torque values when compounded into the ABS matrix because of a self‐lubricating effect. The two‐step FENCF composites exhibited particularly significant advantages. The torque values for the two‐step FENCF/ABS composites were about one‐half of those for carbon fiber/ABS composites in compounding processes; in addition, the former had an average mean fiber length almost 2.5 times that of the latter. The multiyield phenomena in stress–strain curves of FENCF/ABS composites implied that the PTFE powders mounted on Ni/P films slid during stress–strain action. The electromagnetic interference shielding effectiveness of FENCF/ABS composites did not decrease significantly even though the PTFE powders formed a discontinuous phase on the electroless Ni/P films. The mechanical properties of FENCF composites were enhanced because of the larger fiber length. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1661–1668, 2002     

Synthesis of monodisperse nickel‐coated polymer particles by electroless plating method utilizing functional polymeric ligands

In the electroless plating process, to omit a sensitizing process with SnCl₂, we utilized amino‐functional groups on polymer particles. At first, highly monodisperse functional polymer particles could be prepared by a two‐step seeded polymerization of styrene, divinylbenzene, and glycidyl methacrylate. Then, surface epoxy‐functional groups were converted to amino‐functional groups by treating the particles with a diamine. By using these surface amino functionalities, we tried to prepare uniformly metal‐coated monodisperse polymer particles by electroless plating method. The constituents of an electroless nickel solution bath are nickel salt, a reducing agent, suitable complexing agents, and stabilizers. And the metal thickness was simply controlled by changing the loading amount of substrate polymer particles. Morphological observation of nickel‐plated polymer particles was conducted by using optical microscopy, scanning electron microscopy, and transmission electron microscopy. The structural composition of plated nickel was also investigated. Most of all, the function and the efficiency of the amino‐functional group of polymer particles as a polymeric ligand for metal binding was elucidated. From all observations, it was evident that in the electroless metal plating process without any sensitization step, the deposition of metal clusters on substrate particles is largely dependent upon the particle surface functionality. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3801–3808, 2006     

心电图仪用ABS塑料纽扣上化学镀银的大批量氯化

银/氯化银(Ag/AgCl)电极有多种应用,心电图仪用一次性Ag/AgCl电极便是其中之一。在带有一个直径3mm、长5mm的柄的ABS塑料钮扣(直径10 mm)的一个面上,尝试以二价钴为还原剂,化学镀一层1～2μm的银,然后在酸化的氯化物溶液中以化学镀银表面为阳极进行氯化处理。为了获得良好的Ag/AgCl电对,只有平面部分是氯化物而并非将整个覆银表面都转化。上述柄用作金属接点依次与探针连接。由于原材料是ABS塑料,且每毫克的覆银量只有1μm左右,因此损失降到最低。     

Electroless plating of moisture‐curable polyurethane undercoating films

The compatibility of using moisture‐curable polyurethane (MCPU) system as a thin undercoating layer with electroless plating process was evaluated. The characteristics of the MCPU before and after chemical etching treatment were analyzed using atomic force microscope (AFM), scanning electrode microscope (SEM), contact‐angle measurements, and (Fourier‐Transform Infrared) FTIR spectroscopy. We found that surface morphology and roughness of the MCPU is affected by curing period and etching times. A proper combination of curing period and etching times are critical for obtaining a fully metallized surface. All MCPU samples that were etched for 15 min show poor plating performance due to surface damage caused by mild etching treatment. A standard pull‐off testing method (ASTM 4541) was used to evaluate the adhesion strength of nickel–MCPU. Only samples that were postcured for 4 days show influence of surface roughness on adhesion strength. On average, samples that were postcured for 7 days before electroless plating showed better adhesion of nickel–MCPU compared with samples that were postcured for 2 or 4 days. The results show that MCPU system can be used as a thin undercoating layer for electroless plating. It also offers smooth metal–polymer interface and therefore has the potential to be exploited for use in many electroless plating applications including in the decorative such as ornaments and display items and also in electronic industries. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1554–1565, 2007     

Polycarbonate blends with styrene/acrylonitrile copolymers

Lap shear adhesion between laminated sheets of polycarbonate and styrene/acrylonitrile copolymers exhibits a sharp maximum when the acrylonitrile content of the copolymers is in the range of 25–27% by weight. Observations of shifts in glass transitions of the two phases in melt-mixed polycarbonate/SAN blends suggest partial miscibility of one polymer in the other, and this solubility is at a maximum when the SAN copolymer has an acrylonitrile content in the same range causing maximum adhesion. Mechanical properties of injection-molded blends of polycarbonate with various SAN copolymers were also best when the acrylonitrile content was the same as that giving maximum adhesion. The partial miscibility behavior in blends as a function of acrylonitrile content of the copolymer is explained qualitatively in terms of a simple binary interaction model.     

Electropolymerization of monomers on metal electrodes

The use of electropolymerization to coat metal electrode surfaces with polymers formed in situ was investigated in detail. Electrolysis was carried out in a three-compartment cell with fritted disk separators such that polymerization occurred in the middle compartment only. Both anodic and cathodic reactions were utilized to form coating on pretreated metal surfaces. It was shown that polymerization occurred both by vinyl polymerization of olefin monomers as well as by ring-opening reactions of cyclic monomers. The factors that control the coating thickness, the morphology of the polymer deposit, and the adhesion of the polymer formed to the metal substrates were determined. It was found that the growth of the coating on electrode followed the chain polymerization kinetics to a considerable degree. However, increased current did not necessarily lead to increased coating thickness because it also led to increased early termination of growing polymer chains to form soluble low molecular weight products. Water, because of its high surface tension, encourages physical adsorption on metal surfaces of organic monomers dissolved in it. Thus, water was found to be unique as solvent for obtaining coatings with good adhesion to metal substrates. Coatings formed were analyzed by several methods including infrared spectroscopy. Several types of bonding, other than bond formation caused by polymerization reactions, were identified. Finally, the cyclization of polyacrylonitrile was observed when the coating was obtained on aluminum cathode during electrolysis of acrylonitrile–sodium nitrate–DMF solution.     

Plating technology for electronics packaging

With the miniaturization of electronic devices, the connection reliability between integrated circuits (IC) and the external circuits has become important. Electroplating and electroless plating have been applied for the metallization of electronic components. Recently, advanced plating technology is strongly in demanded for the manufacturing of electronic components, because many devices are becoming finer and more complicated. In this paper, we focus mainly on the plating technologies for the preparation of micro-electronic components. The bump formation by electro and electroless plating, via-filling by copper electroplating, improvement of adhesion strength between the insulation layer and the deposited metal, and the preparation of anisotropic conductive particles have been investigated.     

The adhesion between electrolessly deposited copper and a photoimageable polymer

We investigated the relationship between the peel adhesion of copper, deposited by electroless plating, to a photoimageable polymer and the time of chemical etching before plating. Mechanical interlocking is generally considered as being the adhesion mechanism between deposited metals and substrates. However, we found that the peel strength decreased with an increase in the etching time though the polymer roughness did not change. The glass transition temperature of the photoimageable polymer became lower as the etching time increased. The pretreatment not only roughened the surface of the photoimageable polymer, but also affected the bulk polymer and the adhesion.     

Study of compatibility between aliphatic polyketone terpolymer and poly(styrene-r-acrylonitrile)

Compatibility studies have been conducted for polyketone (PK) and styrene–acrylonitrile (SAN) blends in which SAN polymers have different acrylonitrile (AN) contents. Measurements of mechanical properties exhibit the immiscibility of PK/SAN blends. Glass transition temperature shifts and width broadening of the glass transition mean partial compatibility in the amorphous region of the PK/SAN blends. Peak shifts of the CO functional group are larger for PK/SAN48 than that of PK/SAN40 blend. In morphological observations, the dispersed domains appear more refined for the PK/SAN48 blend and the PK/SAN48 blend has better boundary adhesion between the two phases. The Flory–Huggins interaction parameters simulated for the PK/SAN mixture were at a low level and the PK/SAN48 blend showed lower values than the PK/SAN40 blend. This means that the PK/SAN polymer blend is partially compatible in the amorphous region. The level of compatibility tends to increase as the AN content of the SAN polymer increases. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48743.     

Analyse von Acrylnitril-Styrol-Copolymeren mit Hilfe der Pyrolyse-Gaschromatographie

Copolymers of acrylonitrile and styrene with various compositions and molecular weights have been pyrolysed at a temperature of 500°C. The degradation products have been separated by means of gaschromatography and 16 compounds were identified. The most important products are cyanic acid, acetonitrile, acrylonitrile, propionitrile, toluene, ethylbenzene and styrene. The formation of these products has been investigated quantitatively as a function of the composition of the copolymers. Plotting the quantitatively determined amount of the cyanic acid as a function of the copolymer composition a linear slope resulted. Thus a method was developed to analyse copolymers of acrylonitrile and styrene. The formed amounts of acetonitrile, acrylonitrile and propionitrile during pyrolysis are independent on the molecular weights of the copolymers.     

Zum Fließverhalten von kurzglasfasergefüllten Styrol-Acrylnitril-Copolymeren

The viscosity of high polymer melts increases usually when adding fibres. Such an increase has been measured for a short fibre reinforced styrene/acrylonitrile copolymer with 25 and 35% (by weight) glasfibres on a rotational viscometer in the range of shear rates from 10^?3 to 10¹s^?1 for different temperatures and pressures. The viscosity curves show a zero shear viscosity. Its dependence on temperature, pressure and concentration of fibres can be described by straight lines. Furthermore it is possible to shift the viscosity curves in a way that they form a temperature- and pressure-independent, and even a concentration-independent master curve.     

Plasma-modified polyethylene membrane as a separator for lithium-ion polymer battery

The surface of polyethylene (PE) membranes as a separator for lithium-ion polymer battery was modified with acrylonitrile (AN) using the plasma technology. The plasma-induced acrylonitrile coated PE (PiAN-PE) membrane was characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and contact angle measurement. The electrochemical performance of the lithium-ion polymer cell fabricated with the PE and the PiAN-PE membranes were also analyzed. The surface characterization demonstrates that the enhanced adhesion of the PiAN-PE membrane resulted from the increased polar component of surface energy for the PiAN-PE membrane. The presence of the PiAN induced onto the surface of the membrane via the plasma modification plays a critical role in improving the wettability and electrolyte retention, the interfacial adhesion between the electrodes and the separator, the cycle performance of the resulting lithium-ion polymer cell assembly. The PiAN-PE membrane modified by the plasma treatment holds a great potential to be used as a high-performance and cost-effective separator for lithium-ion polymer battery.     

Zur kenntnis der kathodisch angeregten polymerisation von acrylnitril

The reduction in water content to less than approximately 1 · 10^?3 m has a marked influence on the polymerization of acrylonitrile initiated by electrolysis at the cathode, although the anionic mechanism is retained and no living polymers are formed. Polymer yields and viscosity numbers are heavily increased in comparison to systems which have been dried less extensively. A purely white polymer is formed instead of the yellow polymer otherwise obtained at the cathode. There are great variations in polymer yields and polymer viscosity numbers when different organic quaternary ammonium and phosphonium salts are applied as supporting electrolytes. This is attributed to the influence of the counter ion on the rate of propagation and termination. The addition of small amounts of water practically causes these differences to disappear, water playing the role of an efficient, and strongly retarding chain transfer agent. The mechanism of polymerization is discussed.     

铝活化塑料表面化学镀铜新工艺研究

介绍一种使用铝粉为活化剂的置换化学镀铜的新工艺,重点探讨了在(丙烯腈/丁二烯/苯乙烯)共聚物(ABS)材料表面制备含铝-环氧树脂活化涂层过程中,铝粉的粒径、含量及涂层厚度等工艺条件对ABS镀铜层表面形貌、结合力及导电性的影响。优化设计的工艺可以替代传统的钯活化前处理工艺,且不使用有毒的甲醛还原剂;该工艺适用于各种塑料、金属甚至玻璃等基材表面的化学镀铜。     

Multilayer Metal Film Plating on Glass

It has been shown that an under-layer of SiO₂ · nH₂O on a silicate glass surface, promotes the adsorption of Sn(II) hydroxycompounds, resulting in the formation of Sn–O–Si chemical bonds. It also: contributes to the formation of monodispersed Sn(II) compound nanoparticles; levels the glass surface micro-relief; ensures the deposition of fine-grained metal films; increases the rate of Ni–P and Cu electroless plating; and increases the rate of the adhesion interaction between the surface of the silicate glass and metal films. It opens up the possibility of electroless and electrochemical plating of 5–10 μm thick multilayer metal and alloy films.     

Microstructure,adhesion strength and failure path at a polymer/roughened metal interface

Metals and polymers are extensively used in microelectronics packaging where they are joined together. Since both the yield and reliability of packages are strongly affected by the interfacial adhesion between polymers and metals, extensive studies have been performed in order to improve the resistance to debonding of many resulting interfaces. In the present work, the interfacial fracture energy of representative polymer/metal interfaces commonly encountered in micoroelectronics packaging was characterized. A copper-based alloy leadframe was used as the metal and an epoxy molding compound (EMC) was used as the polymer. The leadframe surfaces were roughened by chemical oxidation in a hot alkaline solution and molded with the EMC. In general, roughening of metal surfaces enhances their adhesion to polymers by mechanical interlocking, yet often produces a cohesive failure in the polymer. Sandwiched double-cantilever beam (SDCB) specimens were employed to measure the adhesion strength in terms of interfacial fracture energy. After the adhesion test, the microstructures of metal surfaces before molding with the EMC were correlated to the adhesion strength, and the fracture surfaces were analyzed using various techniques to determine the failure path.