Epoxy Polymer Surface Roughness Modeling Based on Kinetic Studies of Wet Chemical Treatments

Siau, Sam; Vervaet, Alfons; Calster, André Van; Swennen, Ives; Schacht, Etienne

doi:10.1149/1.1766314

Cited by 18 publications

(51 citation statements)

References 23 publications

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“…The sweller caused reorientation of the polar groups toward the surface, making the surface more polar. 8 This confirms the result of FTIR analysis. Similar to the results of FTIR analysis, postoxidation rinsing and subsequent drying of the sample caused the sample to regain its hydrophobicity (contact angle, 110.8°).…”

Section: Change In Other Surface Propertiessupporting

confidence: 85%

Desmearing of FR4 Epoxy Resin Using NMP-Based Sweller

Cheng

Hsu²,

Lan³

et al. 2009

Journal of Elec Materi

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Drilling plate-through holes in multilayered printed circuit boards usually leaves a smear of dielectric material on the conductive surfaces which needs to be removed prior to deposition of conductive material. Desmearing utilizes sweller solutions to enhance smear removal. This study investigated the effects of varying the concentration of n-methyl-2-pyrrolidinone-based (NMP-based) sweller, temperature, and application time on smear removal. Diffusion coefficients were computed from weight gain versus time data, then correlated with temperature using an Arrhenius-type equation. The degree of smear removal was determined by measuring the amount of polymer oxidized over time. From the weight loss versus time data, the desmearing conditions that yielded a maximum weight loss of 0.42 mg cm À2 smear (at constant oxidation conditions) were determined to be 75 vol.% sweller solution, 353.2 K, and 2 min treatment time. Changes in surface characteristics due to sweller treatment and subsequent smear removal were qualified by examining the surface morphology of the polymer by scanning electron microscopy (SEM), identifying changes in functional groups by Fourier-transform infrared (FTIR) spectroscopy, and measuring changes in contact angles.

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Section: Change In Other Surface Propertiessupporting

confidence: 85%

Desmearing of FR4 Epoxy Resin Using NMP-Based Sweller

Cheng

Hsu²,

Lan³

et al. 2009

Journal of Elec Materi

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“…[9][10][11] A model was developed as to how the polymer chain is broken down at its surface during oxidation treatments. This model is used to develop the kinetics of roughness formation at the polymer surface.…”

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confidence: 99%

Kinetic Study of Wet Chemical Treatments on the Surface Roughness of Epoxy Polymer Layers for Buildup Layers

Siau

Vervaet

Nalines

et al. 2004

J. Electrochem. Soc.

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The adhesion of plated metal layers to epoxy polymer surfaces is of prime importance for the reliability of interconnections in microelectronics. An increase in the roughness of the polymer surface, caused by chemical treatment, plays an important part in the adhesion strength of plated metal layers by increasing the total area of interaction between both layers. This kinetic study of the influence of chemical treatments on the surface of the polymer consists of two parts. In Part I the kinetics of sweller treatments and of the solvent were examined in detail and a kinetic model for the influence of sweller and solvent was developed. In this second part the kinetics of the formation of roughness at the polymer surface due to oxidative liquid treatments is examined. A kinetic model is developed based on experimental studies, compromising the combined effects of sweller-oxidizer treatments and the influence of diffusion of the different components. A number of examples are given and verified by experiment. The roughness of the treated polymer samples is measured experimentally by atomic force microscopy. Time-dependant mass measurements were used to record mass changes due to diffusion and reaction.The continuing striving in microelectronics to miniaturize and/or the necessity for electronic circuits to operate in harsh environments, together with the increased signal frequencies and higher density of functions necessary, necessitates further advances in interconnection technologies. A prime requirement for these is a good adhesion between polymers and plated copper layers. It is obvious that the surface properties of the polymer have a big impact on the adhesion of the metal to the polymer. By chemical treatment of the surface the characteristics ͑physical and chemical͒ of it can be changed in order to improve adhesion. Hence there has been intense recent research into improving the adhesion of plated copper onto polymer surfaces.A number of publications 1-3 exist on surface treatments with wet chemicals to improve adhesion strength of copper on epoxy resins. These authors made a phenomenological study on copper laminated foils but not on plated copper surfaces. Li and Tummala 4 studied the effect of wet chemical pretreatments on the interfacial adhesion between plated copper layers and epoxy polymers. According to these authors adhesion between two layers depends first on the physical and mechanical adhesion, caused by the roughness between both layers, and second on the chemical adhesion which is caused by interactions between polymer molecules and the plated metal. These findings are based on earlier work described by Wake. 5 The effects of wet chemical treatments on interfacial adhesion and roughness has not been well studied and understood, 6,7 Recently Ge et al. 8 studied the influence of surface modification on epoxy/copper systems. According to these authors wet-chemical treatments produce a large number of microcavities to anchor deposited electroless copper. Mechanical interlocking was found to have a do...

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“…The untreated samples ͑surface type 1͒ are samples that are coated, dried, and stored in an exsiccator. These samples are the same as those used in our previous publications, [17][18][19][20][21] where the properties of these samples were examined in great detail. The roughness of the surface is very limited ͓around 11 nm rootmean-square ͑rms͒ roughness measured by AFM͔ and contains a small amount of secondary alcohol functions and diol functions, which act as sites where oxidation takes place.…”

Section: Methodsmentioning

confidence: 99%

“…According to Coppens, 16 a fractal surface also influences diffusion of components. In order to maximize adhesion, Wool and Long 15 suggested development of pretreatments that can generate fractal surfaces to which high adhesion by mechanical interlocking could be expected.The kinetics of roughness formation due to wet-chemical treatments was extensively studied in our previous publications, [17][18][19][20] in which the effects of swellers and oxidizers in the bulk of the polymer and on its surface were qualitatively and quantitatively determined. These previous studies revealed a number of synergetic effects between the sweller and oxidizer treatments.…”

mentioning

confidence: 99%

“…The kinetics of roughness formation due to wet-chemical treatments was extensively studied in our previous publications, [17][18][19][20] in which the effects of swellers and oxidizers in the bulk of the polymer and on its surface were qualitatively and quantitatively determined. These previous studies revealed a number of synergetic effects between the sweller and oxidizer treatments.…”

mentioning

confidence: 99%

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Chemical Modification of Buildup Epoxy Surfaces for Altering the Adhesion of Electrochemically Deposited Copper

Siau¹,

Vervaet²,

Schacht

et al. 2005

J. Electrochem. Soc.

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The adhesion of electrochemically deposited copper on top of chemically surface modified epoxy layers for buildup purposes is examined. Using a wet-chemical surface synthesis reaction iminodiacetic acid, imidazole, and mercaptopyrimidine groups were chemically imprinted on the surface of buildup epoxy layers based on nucleofilic substitutions. The synthesis was followed by an identical electroless Cu deposition and peel strength measurement sequence. The identity of certain groups at the surface has pronounced influence on the adhesion strength of electrochemically deposited metals and is compared with traditional swell/ oxidation treatments of the surface of the polymer. By varying the identity of the chemical groups at the surface, the chemical part of the adhesion can be altered. The changes in roughness of the polymer surface were minimized by choosing solvents that exhibit minimum diffusion into the polymer and by limiting the reaction temperature. In this way the changes in the physical part of adhesion could be kept to a minimum. The chemical composition of the surface is examined by attenuated total reflection-infrared and X-ray photoelectron spectroscopy measurements. Weight changes were recorded after each separate wet-chemical treatment. Surface synthesis influences the peel strength negatively or positively and modifies the deposition rate and etching speed of electrochemically deposited copper.The surface properties of the polymer obviously have a big impact on the adhesion strength of electrochemically deposited metals on epoxy polymers used for buildup purposes. By chemical treatment the characteristics ͑physical and chemical͒ of the polymer surface can be changed in order to improve adhesion. Hence there is intense recent research into improving the adhesion of plated copper onto polymer surfaces. A number of publications 1-6 exist on surface treatments with wet chemicals to improve adhesion strength of electrochemical deposited copper on polymers.The study of the mechanisms of adhesion uses various concepts, emphasized by the fact that many theoretical models of adhesion have been proposed. These theories are both complementary and contradictory. 7 The five theories used are mechanical interlocking, electronic theory, the theory of boundary layers and interfaces, adsorption ͑thermodynamic͒ theory, and chemical bonding theory. 7 All theories consider two parts of adhesion: The physical or mechanical part of adhesion, which is linked to the roughness of the interface, and the chemical part of adhesion, caused by the interactions between the materials of both layers.The mechanical interlocking theory, proposed originally by MacBain and Hopkins, 8 conceives of mechanical keying or interlocking of one substance into cavities, pores, and asperities of the other material to be the major factor in determining adhesive strength. However, the possibility of establishing a good adhesion between smooth surfaces leads to the conclusion that the theory of mechanical keying cannot be universal. To overcome this...

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Epoxy Polymer Surface Roughness Modeling Based on Kinetic Studies of Wet Chemical Treatments

Cited by 18 publications

References 23 publications

Desmearing of FR4 Epoxy Resin Using NMP-Based Sweller

Desmearing of FR4 Epoxy Resin Using NMP-Based Sweller

Kinetic Study of Wet Chemical Treatments on the Surface Roughness of Epoxy Polymer Layers for Buildup Layers

Chemical Modification of Buildup Epoxy Surfaces for Altering the Adhesion of Electrochemically Deposited Copper

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