Showing papers in "Journal of Adhesion in 2000"

Analysis of the symmetrical 90°-peel test with extensive plastic deformation

Abstract: A numerical 2-D study of the symmetrical 90°-peel test (a similar geometry to the T-peel test) in which extensive plastic deformation occurs in the adherends is presented in this paper. A traction-separation relation is used to simulate failure of the interface, and the conditions for both crack initiation and steady-state crack growth are investigated. The numerical predictions for the steady-state peel force are compared with those based on elementary beam theory. It is shown that two competing effects dominate the mechanics of the peel test to such an extent that the results of beam-bending analyses cannot be used to predict the peel force. At one extreme range of parameters, delamination is driven by shear rather than by bending, resulting in a lower peel force than would be predicted by beam-bending analyses. At the other extreme, where delamination is bending-dominated, the constraint induced by the interfacial tractions cause an increase in the peel force. The numerical results are compare...

Surface Characterization of Vulcanized Rubber Treated with Sulfuric Acid and its Adhesion to Polyurethane Adhesive

Abstract: Modifications produced on a vulcanized styrene –butadiene rubber surface by treatment with sulfuric acid were studied and several experimental variables were considered. The treatment of R1 rubber with sulfuric acid produced a noticeable decrease in contact angle which was mainly ascribed to an increase in surface energy due to the formation of sulfonic acid moieties and C˭O bonds, and the removal of zinc stearate. The rubber surface swelled and became brittle as a result of the treatment, and when flexed microcracks were created. A rubber surface layer modification was produced with a consequent decrease in tensile strength and elongation-at-break values. The treatment enhanced the T-peel strength of R1 rubber/polyurethane adhesive joints and the locus of failure was cohesive in the rubber. The optimum immersion time in H2SO4 solution was less than 1 min., and the reaction time in air was not found to be critical; the neutralization with ammonium hydroxide and the high concentration of the sulfu...

The Effect of Relative Humidity on Particle Adhesion and Removal

Abstract: The removal of small particles is vital for contamination-free manufacturing. In humid environments liquid can condense between the particle and substrate and give rise to a very large capillary force, which increases the total force of adhesion. The removal and adhesion forces of polystyrene latex (PSL) particles and pigmented coating chips were measured on silicon, polyethylene terephthalate, metallized and polyester coating substrates as a function of humidity. The results indicate that the capillary force is significant at a relative humidity above 50% and dominates at a relative humidity above 70%. At relative humidity below 45%, the electrostatic force becomes significant. The adhesion forces varied depending on the particles and substrates used, but the trend of high adhesion at high and low relative humidity was observed for all PSL particles/substrate systems. The pigmented coating chips/substrate system however, exhibited high adhesion at high relative humidity and low adhesion at low r...

Experiments and Engineering Models of Microparticle Impact and Deposition

Abstract: This article summarizes, reviews and consolidates some of the research work done by the authors over recent years. It covers a wide variety of topics related to the experimental and analytical investigations of the impact of microparticles with flat surfaces in the presence of adhesion and frictional forces. Over 180 experiments were conducted under vacuum conditions to study the effects of particle size, shape, incident translational and rotational velocities, and substrate surface roughness on the oblique impact response of the particle. Analytical models of the impact process were developed, including an algebraic, rigid-body model and a numerical simulation that can be used to predict rebound and capture conditions and to model the forces and displacements that occur during the contact duration. These models were validated using experimental results. Overall, the article covers impact conditions ranging from the more idealized case of a microsphere impacting a molecularly-smooth surface to th...

New Adhesion Promoters for Copper Leadframes and Epoxy Resin

Abstract: New primer molecules have been synthesized to increase the adhesion strength between a copper leadframe and an epoxy molding compound in microelectronical devices. The coupling agents were preliminarily chemisorbed at the surface of copper plates via special binding groups like thiol, disulfide, ethylene diamine and phthalocyanine. Binding to the epoxy resin was performed via an hydroxyl group. Linear hydrocarbon spacers with various chain lengths connected the copper- and epoxy-binding groups. The self-assembled layers of the organic coupling agents at the metal surface were characterized by X-ray photoelectron spectroscopy. Thermogravimetric analysis was used to study the coating with respect to its corrosion oxidation inhibition. Shear tests clearly indicated that the coupling agents increase adhesion strength and are stable even in extreme humidity and thermal conditions in analogy to IPC-Level-1 pretreatment. Thus, delamination of the microelectronical packages was prevented.

Adhesion: Comparison Between Physico-chemical Expected and Measured Adhesion of Oxygen-plasma-treated Carbon Fibers and Polycarbonate

Abstract: The adhesive interaction between oxygen-plasma-treated, polyacrylonitrile-based, high-tensile-strength carbon fibers and a polycarbonate matrix has been studied. Several models have been used to predict the impact of the plasma treatment process on the strength of adhesion between both jointing partners. These approaches have been the thermodynamic work of adhesion which was calculated from the solid surface tensions, based on the results of contact angle measurements versus test liquids, the contact angle which was directly obtained via polycarbonate melt droplets on single carbon fibers and the zeta (ς)-potential data provided by streaming potential measurements. The results have been compared with the interfacial shear strength determined from the single-fiber fragmentation test. Additionally, the single-fiber tensile strength of the oxygen-plasma-treated carbon fibers was determined. We confirmed that any physico-chemical method on its own fails to describe exactly the measured adhesion. Howe...

Electrochemical Sensors for Nondestructive Evaluation of Adhesive Bonds

Abstract: An in-situ corrosion sensor based on electrochemical impedance spectroscopy (EIS) has been used to detect moisture ingress into aluminum-aluminum and aluminum-composite adhesive bonds. Both wedge tests and tensile button tests (aluminum-aluminum bonds only) were performed. Upon moisture absorption, the impedance spectra change shape with the low-frequency region becoming resistive. The low-frequency impedance decreases by several orders of magnitude, depending on the adhesive and the experimental conditions. For bonds with stable interfaces, such as phosphoric acid anodized (PAA) aluminum, the absorbed moisture causes an initial weakening of the adhesive resulting in reduced strength or small crack propagation. A substantial incubation time prior to substrate hydration and bond degradation allows warning of potential joint deterioration and enables condition-based maintenance. For bonds with smooth interfaces with little or no physical bonding (mechanical interlocking), crack propagation can proc...

Interaction of the Adhesive Protein Mefp-1 and Fibrinogen with Methyl and Oligo (Ethylene Glycol)-terminated Self-assembled Monolayers

Abstract: The interaction of fibrinogen and Mefp-1, the adhesive protein of the common blue mussel Mytilus edulis, with methyl- and oligo(ethylene oxide) (OEG)-terminated self-assembled monolayers (SAMs) has been investigated by Fourier Transform Infrared Reflection (FT-IRAS) analysis. The measurements on the hydrophobic surfaces show that the underlying SAM is structurally undisturbed when the proteins adhere. Mefp-1 is used as an attachment factor (Cell-TakTM) in cell cultures and in biomedical applications, and it is of interest to determine if OEG-terminated surfaces are inert towards Cell-Tak-mediated cell adhesion. We find that, when Langmuir transfer of a protein film at the liquid/air interface is avoided, the moderately hydrophilic hydroxyhexa (ethylene oxide) and methoxytri(ethylene oxide) undecanethiolate SAMs prepared on Au substrates are protein resistant. The inertness of the OEG-terminated surfaces does not depend on any specific protein present in solution, but rather appears to be a genera...

Acrylate Copolymer/Ultraviolet Curable Oligomer Blends as Pressure-sensitive Adhesives

Abstract: For the blends of acrylate copolymer [poly(2-ethylhexyl acrylate-co-acrylic acid); P(2EHA-AA)] with ultraviolet (UV) curable oligomer [urethane acrylate oligomer; UAO], pressure-sensitive adhesive (PSA) properties, such as peel adhesion, probe tack, and holding power were examined. The values of peel adhesion and probe tack of the P(2EHA-AA)/UAO blends were dramatically reduced by UV irradiation. On the other hand, all blends had a high holding power even if these blends were cured by UV irradiation. The mechanism of reduced PSA properties was investigated via dynamic mechanical properties, DSC, and dynamic contact angle (DCA). The peel adhesion decreased monotonically with increasing storage modulus, E′, and loss modulus, E″, for all non-UV and UV-cured blends. Since modulus values and glass transition temperatures, Tg, of these blends after UV irradiation were higher than those of these blends before UV irradiation, we judged that the reduced peel adhesion and probe tack values were caused by t...

The Interaction of γ-Glycidoxypropyltrimethoxysilane with Oxidised Aluminium Substrates: The Effect of Drying Temperature

Abstract: The interaction of γ-glycidoxypropyltrimethoxysilane (GPS) with oxidised aluminium substrates has been investigated in terms of the effect of the drying, or curing, temperature. Samples treated with aqueous solutions of GPS at concentrations of 1,4 and 8% v/v were cured at 25, 50, 93 and 120°C. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to construct adsorption isotherms and determine the thicknesses of the various GPS coatings. A temperature effect induces subtle changes in the structure of the resulting films. The uptake of GPS is increasing with increasing concentration of GPS. The structure of the films changes at a threshold temperature between 50 to 93°C. XPS and ToF-SIMS data both indicate that the interaction of the GPS film on aluminium is different for low and high temperatures drying regimes. Using the Beer-Lambert equation, it was found that increasing the curing temperature leads to the variation of the thickness of s...

Atomic Force Microscope Techniques for Adhesion Measurements

Abstract: The Atomic Force Microscope (AFM) has become a powerful apparatus for performing real-time, quantitative force measurements between materials Recently the AFM has been used to measure adhesive interactions between probes placed on the AFM cantilever and sample surfaces This article reviews progress in this area of adhesion measurement, and describes a new technique (Jump Mode) for obtaining adhesion maps of surfaces Jump mode has the advantage of producing fast, quantitative adhesion maps with minimal memory usage

Measurement of the Adhesion of a Viscoelastic Sphere to a Flat Non-Compliant Substrate

Abstract: The adhesion between a single polystyrene bead (radius, 27 μm) and a flat silica surface has been measured with an atomic force microscope as a function of two variables: (a) The maximum applied load and, (b) the loading time at a constant maximum applied load. Analysis of the results indicates significant plastic deformation of the bead under the action of the load forces. There is also evidence for time-dependent viscoelastic effects as a load is exerted on the bead. The contact zone of the polystyrene bead used for these experiments was examined using Scanning Electron Microscopy. The microscope images revealed a surface covered in small polymer beads with a radius of only 115 nm. In the contact zone these beads had undergone substantial and permanent deformation as a function of the applied load. Basic geometric analysis reveals that the large sphere is not contacting the flat surface under any load. The results presented here indicate the value of being able to measure adhesion using an atom...

Copper-based Conductive Polymers: A New Concept in Conductive Resins

Abstract: The history of making plastic materials conductive to both electric currents and to the transfer of thermal energy has traditionally been accomplished by the addition of metallic particles into a resin matrix. Principally, such metals as aluminum, silver, gold, nickel and copper have been used. Copper has had a limited success due to its tendency to form a non-conductive oxide surface layer and currently such adhesives depend primarily on silver for high conductivity. An intense research effort to eliminate the problems associated with copper-filled conductive polymers resulted in a treatment and preparation of copper flake that allows the stable formation of a conductive structure within a polymer matrix. Once the activated copper particles are in the resin, the formulation is stable. Most of the resins evaluated have been epoxy resins although certain thermoplastic resins have also been made conductive. Volume resistivities as low as 10−5 ohm-cm have been achieved.

Surface Forces and the Adhesive Contact of Axisymmetric Elastic Bodies

Abstract: A synthetic approach to the problem of the adhesive contact of axisymmetric elastic bodies is proposed. A convenient and general formulation is thus obtained, which is shown to yield directly most of the useful models. In particular, the roles of the shape of the indenter on the one hand, and of the nature of the attractive interactions on the other hand are clearly separated. By nature, this approach can also be used in the case where the bodies are in interaction but not in contact. This results in a consistent treatment of long-range interactions and contact properties.

Blistering as a Form of Degradation in Adhesive Joints

Abstract: Water-filled blisters were observed to form during accelerated aging experiments with aluminum adherends and two structural epoxy adhesives. Both closed adhesive joints and open-face specimens were affected. The blisters grew with time, originated both in the adhesive and at the epoxy-aluminum interface, and were found only at 100% relative humidity at both 65°C and 85°C; blisters were never observed at 85% relative humidity or lower. The same water-soluble ionic species were found in the blister liquid, the two adhesives and water that had been in contact with adhesive samples for an extended period. It is proposed that the blisters grew under the influence of osmosis, originating in water clusters at microscopic voids. Contamination of the aluminum adherends by residual etching solution, although not a necessary precondition for blistering, could facilitate this process by lowering the partial pressure at which water condenses and by creating higher osmotic pressures.

Cleavage Strength of Steel/Composite Joints

Abstract: This paper presents the experimental results of an on-going study to examine cleavage strength, particularly at the interface regions of epoxy adhesive with steel and glass reinforced epoxy (GRE) composite. The adhesion is characterised by mechanical testing of cleavage specimens. A standard specimen was modified to allow testing of hybrid joints. The effects of adhesive thickness and various surface conditions of both adherends were examined. Among key conclusions, the study found that cleavage strength is not strongly dependent upon adhesive thickness and that polished composite gives better adhesion compared with polished steel. Test results were analysed and compared with aspects of numerical analyses. The study has also established a new methodology to test hybrid adhesive cleavage joints.

Effect of pre-coated Vs. added coupling agents on the vulcanization of silica-filled polyisoprene

Abstract: Solid-state 13C NMR was utilized in analysis of the crosslink structure in silica-filled polyisoprene. Samples containing either a pre-coated coupling agent, a coupling agent added in the mixing process, or polyethylene glycol (PEG) were vulcanized and the type and density of crosslinking determined. The precoated coupling agent sample gave lower %swelling, lower extraction amounts, and a lower T 2 relaxation than the mixed coupling agent, indicating increased crosslinking or increased filler –rubber interaction. The precoated also showed less cis –trans isomerization than the mixed, which may be due to its more uniform coating effect on the silica. The PEG sample yielded a 13C spectrum similar to an unfilled sample indicating decreased silica adsorption of vulcanization agents. Neither coupling agent significantly decreased the total sulfurization nor the percent monosulfidic crosslinks from that of a silica-filled sample without coupling agent.

Electrochemical Pretreatment of Polymers with Dilute Nitric Acid Either Alone or in the Presence of Silver Ions

Abstract: X-ray Photoelectron spectroscopy (XPS) was used to detect major changes to the surface chemistry of polypropylene (PP), high density polyethylene (HDPE) and styrene-butadiene block copolymer (SBS) caused by electrochemical treatment using dilute nitric acid as electrolyte. Large increases in adhesion levels were observed with PP and HDPE. The method has the potential to be a commercial pretreatment that is inexpensive and safe. Further treatments were carried out in which the complex ion (AgNO3)+ was generated electrochemically. Effective pretreatment was achieved even with dilute solutions (0.001 M w.r.t. silver nitrate). Mechanisms are tentatively proposed for the electrochemical treatment when simply using an electrolyte of dilute nitric acid or where the anolyte consists of a solution of silver nitrate in dilute nitric acid.

A Practical Criterion for Rheological Modeling of the Peeling of Pressure Sensitive Adhesives

Abstract: The transient extensional viscosity of non-crosslinked pressure sensitive adhesives (PSA's) and physically-crosslinked PSA's is measured and compared with theoretical predictions based on the linear viscoelastic (LVE) properties of the PSA's and the use of linear and quasi-linear constitutive equations. Based on a previously-derived expression for the relative contributions of individual relaxation modes of a polymeric material to its transient extensional viscosity, a criterion for whether large extensional deformations can be modeled on the basis of the LVE spectrum is proposed and evaluated for each PSA. The relevance to adhesion is demonstrated in peel tests, where the deformation of adhesive is quantified in images of the peel front under the assumption of uniaxial elongation and used to obtain theoretical peel forces in excellent agreement with measurements. This demonstrates the applicability of the criterion to the peeling process.

Activated Poly(hydromethylsiloxane)s as Novel Adhesion Promoters for Metallic Surfaces

Abstract: A poly(hydromethylsiloxane) (PHMS) was bound to aluminum, copper and steel surfaces via activation with cis-[PtCl2(PhCH [dbnd] CH2)2] in solution at room temperature. The attached polymer promotes the adhesion to two-component silicone resins where the curing process is based on catalytic hydrosilylation of olefins. In lap-shear or peel tests, cohesive failure was always observed. An example shows that the adhesive joint withstood boiling water for 200 h without considerable loss of adhesive strength. It is suggested that a small fraction of the olefinic component of the resin, e.g., a poly(dimethylsiloxane) containing some olefinic groups, is also connected with the attached PHMS via catalytic hydrosilylation, thus binding the silicone resin to the surface via the PHMS layer.

The effect of time and humidity on particle adhesion and removal

Abstract: Time and humidity greatly influence particle adhesion and removal in many particlesubstrate systems. The effect of time (aging) and humidity on the adhesion and removal of 22 μm PSL (Polystyrene Latex) particles on polished silicon wafers is investigated. The results show that the effect of time on the adhesion and removal of the 22 μm PSL particles on silicon substrates in high humidity environment is very significant. The removal efficiency of PSL particles significantly decreased after the samples were aged for more than one day in high humidity environment. The combined effect of the van der Waals force and the capillary force tend to accelerate the adhesion-induced deformation process. When capillary force occurs at the particle substrate interface, the removal efficiency decreases quickly by more than 50% within 24 hours. Without the capillary force, the adhesion-induced deformation is negligible within the first 24 hours.

Bonding of Natural Rubber to Steel: Surface Roughness and Interlayer Structure

Abstract: This paper is concerned with two aspects of the adhesion produced by the vulcanisation bonding of a simple natural rubber (NR) compound to mild steel Adhesion was measured using a 45° peel test When the NR was bonded, using a proprietary bonding agent (Chemlok 205/220), to ‘smooth’ steel (acid etched) or to ‘rough’ steel (phosphated) high values of peel energy (≥ 45 kJm−2), and good environmental resistance to water were obtained, with failure cohesive largely within the rubber The highest values of peel energy (≈ 75 kJm−2) were associated with a phosphated surface which consisted of plate-like crystals which directed the stresses away from the substrate in a way which produced a failure surface within the rubber which showed extensive tearing and cracking The nature of the layer formed in the interfacial region by interaction between bonding system and rubber was investigated using a chlorinated rubber as a ‘model compound’ representing the adhesive and uncompounded NR to represent t

Recent theoretical results for nonequilibrium deposition of submicron particles

Abstract: Selected theoretical developments in modeling of deposition of sub-micrometer size (submicron) particles on solid surfaces, with and without surface diffusion, of interest in colloid, polymer, and certain biological systems, are surveyed. We review deposition processes involving extended objects, with jamming and its interplay with in-surface diffusion yielding interesting dynamics of approach to the large-time state. Mean-field and low-density approximation schemes can be used in many instances for short and intermediate times, in large enough dimensions, and for particle sizes larger than few lattice units. Random sequential adsorption models are appropriate for higher particle densities (larger times). Added diffusion allows formation of denser deposits and leads to power-law large-time behavior which, in one dimension (linear substrate, such as DNA), was related to diffusion-limited reactions, while in two dimensions (planar substrate), was associated with evolution of the domain-wall and def...

FT-IR and Temperature-programmed Desorption (TPD) Study of the Adsorption of Probe Molecules Used to Model Epoxy Resin Adhesion to Chromium, Iron and Stainless Steel Substrates

Abstract: In this study, we investigated the reactivity of chromium, iron, and surface-treated 304L stainless steels (SS) toward molecules representing model epoxy resins These molecules were ammonia (a basic probe molecule also representative of the hardener amine group), 1,2-epoxybutane (for epoxy groups) and 2(methylamino)ethanol (for the β-amino alcohol resulting from the reaction of epoxy with amine) These molecules were analyzed in the adsorbed state by either FT-IR or temperature-programmed desorption (TPD) Surface analysis showed that the top surface of the treated 304L samples only contains chromium and iron as metallic elements The chromium/iron ratio can be varied within a wide range according to the SS surface treatment used When increasing the SS surface chromium enrichment, we show a simultaneous increase of (i) both density and strength of surface acid sites, (ii) the amount of β-amino alcohol adsorbed In addition, there is a marked improvement of the epoxy resin/304L bond strength whe

Adhesion Strengths of Epoxy Molding Compounds to Gold-plated Copper Leadframes

Abstract: In the present study, the effects of plasma cleaning on the adhesion strength of molding compounds to gold-plated copper leadframes are presented. Important process parameters such as the type of gasses used and the time exposed in air before molding are specifically evaluated. The leadframe pullout test is performed to measure interfacial bonding strengths. The liquid droplet test is used to measure contact angles and atomic force microscope (AFM) is employed to characterize quantitatively the roughness of modified surfaces to correlate with the bond strength measurements. The results indicate that plasma cleaning of leadframes has three major ameliorating effects, namely, surface cleaning due to the removal of contaminants, enhanced chemical compatibility with molding compounds and surface roughening with associated larger surface contact area for better mechanical interlocking. Exposure of plasma-cleaned leadframes in air before molding is detrimental to interface bond quality, a finding sugge...

Creep Effects in Nanometer-scale Contacts to Viscoelastic Materials: A Status Report

Abstract: Effects of creep on the behavior of nanometer-scale contacts to viscoelastic materials are described from the viewpoint of the contact mechanics theory developed by Ting The two most important effects are: (1) The time at which maximum contact area and maximum deformation occur can be delayed substantially from the time of maximum applied load (2) The deformation at separation is related to the loss tangent These long-range effects due to creep are distinct from the much shorter-range crack tip effects induced by adhesion at the periphery of the contact and associated with the names Barquins and Maugis Consideration of relevant time scales reveals that creep effects are expected to dominate in SFM-scale contacts for a wide range of compliant viscoelastic materials Guidelines for selection of optimal experimental parameters for nanometer-scale studies are presented The need for a comprehensive theory is emphasized

Cohesive Zone Models of Polyimide/Aluminum Interphases

Abstract: The fracture energy required to delaminate PMDA/ODA polyimide films from aluminum substrates was determined using the circular blister test. Films were prepared by spin coating the polyamic acid of PMDA and ODA onto polished aluminum substrates, by vapor co-deposition of PMDA and ODA monomers onto polished aluminum substrates, or by spin-coating the polyamic acid onto polished aluminum substrates that were first coated with thin layers of γ-aminopropyltriethoxysilane (γ-APS). Elastic and elastoplastic analyses were used to extract the fracture energies from the blister test results. Elastoplastic analysis provided fracture energies that ranged from 579 J/m2 for spin-coated films on polished substrates to 705 J/m2 for vapor-deposited films on polished substrates and to 750 J/m2 for spin-coated films on silanated substrates. These values were intermediate between those provided by the two different elastic analyses. Differences in fracture energy determined by the three different analysis methods w...

Adhesive Properties of Cured Phenylethynyl-Containing Imides

Abstract: As part of a program to develop structural adhesives for high-performance aerospace applications, work has continued on phenylethynyl-containing imides. Initial work on linear phenylethynyl-terminated imides (PETI), led to a material called LaRC™ PETI-5, which is now commercially available and was selected as the composite matrix resin and adhesive on the High Speed Research Program. In this report, the preparation and evaluation of a series of modified phenylethynyl-containing imides, which are being developed as secondary bonding adhesives, will be discussed. The modification of these materials compared with the linear material involves the use of a small amount of trifunctional monomer to introduce branching. These adhesives exhibit excellent processability at pressures as low as 15 psi and temperatures as low as 288°C. The cured polymers exhibit excellent solvent resistance and high mechanical properties. Polymer properties can be controlled by varying the molecular weight, the amount of bran...

Adhesion of Cancer Cells to Endothelial Monolayers: A Study of Initial Attachment Versus Firm Adhesion

Abstract: For most cancer patients, the ultimate cause of death is not the primary tumor itself, but metastasis, or the spread of cancer from the primary tumor throughout the body. The formation of tumor foci at sites distant from the primary tumor is a multistep process which includes dissemination of the cancer cells through the blood stream and hence, interactions with the endothelium lining the blood vessels walls. At least two theories have been proposed for explaining the interaction between cancer cells and endothelium. According to one theory, the tumor cells roll along the endothelium and the rolling velocity decreases until the cells become firmly attached to the vessel wall. In another theory, the circulating cancer cells must first lodge inside small vessels before they attach to the endothelium. In the latter case, the cells would only metastasize in the smaller vessels where lodging can occur. To gain further insight into the process of metastasis, the adhesion of human breast cancer cells to...

Relative Adhesion Measurement for Thin Film Microelectronics Structures

Abstract: There is a difference between technologically-important adhesion or practical adhesion, and fundamental or basic adhesion. What is important in the understanding of fundamental adhesion may be of insignificant interest to technology. A manufacturer is interested in how to improve the reliability of the structure being built should an interface problem exist, rather than knowing the precise value of the fundamental adhesion. It is not possible to measure fundamental adhesion for technologically-important structures due to the inability to account for all energy dissipating processes during the test. Adhesion measurements are plagued with the mode of interface loading issue: the resemblance of test interface loading to that of the actual manufactured part. What technology needs is a simple adhesion test method that is practical for product development, giving reliable information about the interface integrity. The present paper compares the value of two adhesion tests for microelectronics applicati...