摘要:

AbstractPreliminary results of a systematic investigation of the behavior of encapsulating materials used in electronic packaging are reported. In this study, the radii of curvature of silicon wafers encapsulated with a filled epoxy are obtained by X‐ray diffraction. The values recorded agree closely with Dektak scanning for thin coatings. However, deviations occur with thicker layers due to the fundamental difference in the parameter measured by both techniques. Analytical solutions are proposed for both one‐and two‐sided encapsulation. Results predicted for the one‐sided coating describe a more severe state of stress within the package, and a correspondingly higher curvature than observed. X‐ray radiographs and optical micrographs of molded packages reveal the presence of internal voids and surface cracks. Such defects relax the stresses within the composite system and may account for the discrepancy

ISSN:0032-3888    

DOI:10.1002/pen.760281602

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe residual stresses caused by polyiinide (Pi 5878 and PI 2566), and silieone (3‐6550 and 1‐2577) films used as passivation/encapsulation layers in microelectronic circuit manufacturing are investigated by X‐ray curvature measurements. For both PI types, the maximum stress is between 20–40 MPa. This stress is independent of film thickness for films thinner than 10 μm. For films thicker than this value, however, some dependency of the film stress on film thickness is observed. The variation of stress during the cure cycle is significantly different for PI 5878 and PI 2566. This is due to void nucleation and growth in the 5878 films during solvent volatilization. The silieone films have no residual stress at room temperature for all thicknesses. The compensating stresses in the Si wafer are insignificant for all cases

ISSN:0032-3888    

DOI:10.1002/pen.760281603

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractA new concept based on differential scanning calorimetry (DSG) is introduced which enables us to make a rapid estimation of the thermal conductivity of materials. This technique is shown to give reasonable agreement with the literature data and offers unique advantages, e.g. short analysis time, no instrument modification, small thermal radients across the sample, spall sample size requirements, and most importantly it can be applied to polymer melts. Although our data falls within the literature range, it is difficult to comment on its accuracy since the literature itself shows a wide variation. The precision of our measurements is better than ±20 percent which is considered adequate for thermal conductivity evaluation. As a matter of convenience, we have also presented briefly, a background of the thermal conductivity measuring techniques

ISSN:0032-3888    

DOI:10.1002/pen.760281604

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractOver the last four decades, numerous reports have appeared on the physico‐chemical kinetics, especially crystallization kinetics, based on the Avrami equation, ϕ = exp [−Ktn] where ϕ is the fraction of material unchanged at timet,Kis an overall rate constant and “n” is the Avrami exponent indicative of process mechanism. The usage of the Avrami equation has been limited to the determination of “n” and its temperature dependence. It is shown that the evaluation of K and the activation energy (E) using this equation is erroneous sinceKandEare both influenced by “n” although such would be unexpected from the Avrami equation. On the other hand, if one uses a modified expression, ϕ = exp[−Kt]n, then in addition to the value of “n”, correct values ofKandEare obtained. This retains the original correspondence of the Avrami equation to nuclea‐tion and crystal growth processes but extends its applicability to (i) correctly evaluateKandEparameters, and (ii) correctly compare transformation rates when the systems differ in theirnvalues. Experimental data are presented to

ISSN:0032-3888    

DOI:10.1002/pen.760281605

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractA general description of the thermpgravimetric‐mass spectroscopy (TG‐MS) technique is presented. Advantages and limitations are discussed with respect to other mass‐spectral techniques, and a few examples of applications of TG‐MS to the study of the thermal degradation of polymers ar

ISSN:0032-3888    

DOI:10.1002/pen.760281606

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractRheological properties of toluene solutions of nitrile butadiene rubber, of different molecular weights (Mw, 290,000,320,000, and 450,000) and acrylonitrile contents (30 and 40 percent), were investigated at low (0.1 S−1) to medium (20,0 S−1) shear rates, in order to determine their feasibility for dip‐coating applications. The effect of a surface‐active additive, bentonite, and the solid content (15 and 20 wt percent) on solution viscosity was of main interest. At low zero‐shear viscosity (100 Pa‐·S) the coating showed poor leveling. Zeroshear viscosity was found to be less affected by bentonite than oligomer‐based solutions, at the same time, the solid content and the molecular weight of the polymer had more pronounced effects. With a proper balance of the parameters, seamless coating films were achieved, with excellent tensile and tear properties, and good permeation resistance

ISSN:0032-3888    

DOI:10.1002/pen.760281607

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe heating and flow behavior of thermoset molding compound within the pot of a transfer molding process were studied with flow visualization experiments and a mathematical model. The flow pattern within the pot was found to be a stagnation point flow. The extrudate temperature was only 10°C–15°C above the preheat temperature, and it was relatively constant except for start‐up and termination transients. The chemical conversion of the extrudate was well below the conversion to gel for typical process conditions. Variations in pot diameter, preheat temperature, and pot temperature were also exa

ISSN:0032-3888    

DOI:10.1002/pen.760281608

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractIn this work, a concept of distributed damage, including its inception and propagation, was applied to creep induced buckling of specimens prepared from high density polyethylene (HDPE). Using a kinetic relationship for damage accumulation, an integral equation for the front of the damage zone was derived. A time parameter associated with the inception of the damage front was obtained. The motion of the front was approximated for small times. Long time estimation was obtained using an assumption for a shape of the damage distribution. These results enabled us to review reported experimental results on creep induced buckling using a new insight into the relationship between applied load and time to buckle.

ISSN:0032-3888    

DOI:10.1002/pen.760281609

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThermosetting resin/glass cloth composites find extensive use in the packaging of electrical circuits into multi‐layered circuit boards. To determine optimum processing conditions, it is necessary to understand the rheology of the resin as it cures. In this study, a squeezing flow geometry was used to determine the shear viscosity of a high performance epoxy resin during cure; Viscosity profiles were obtained during rising temperature cure. The results were compared with the complex viscosities obtained using the dynamic oscillatory parallel plate geometry. A numerical optimization algorithm was used to obtain the dual Arrhenius viscosity model parameters from the experimental viscosity data. The sensitivities of the model parameters and their effects on the predicted viscosity profiles were also determine

ISSN:0032-3888    

DOI:10.1002/pen.760281610

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

ISSN:0032-3888    

DOI:10.1002/pen.760281601

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY