摘要 :
Over the years, many analytical and experimental research studies have aimed to improve the state-of-the-art assessment of solder joint integrity from a physics-of-failure perspective. Although much progress has been made, there...
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Over the years, many analytical and experimental research studies have aimed to improve the state-of-the-art assessment of solder joint integrity from a physics-of-failure perspective. Although much progress has been made, there still exist many inconsistent and even contradictory correlations and conclusions. Before discussing some of the prominent inconsistencies found in the literature, this paper reviews the fundamental physics underlying the nature of solder failure...Using the complex constitutive properties of solder, fundamental mechanical and thermomechanical proccesses can be modeled to demonstrate some of the inconsistencies in the literature.
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摘要 :
Numerous process variables can influence the robustness of conventional metal/ceramic brazing processes. Experience with brazing of hermetic vacuum components has identified the following parameters as influencing the outcome of h...
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Numerous process variables can influence the robustness of conventional metal/ceramic brazing processes. Experience with brazing of hermetic vacuum components has identified the following parameters as influencing the outcome of hydrogen furnace brazed Kovar (Trade Name) to metallized alumina braze joints: (a) Mo-Mn metallization thickness, sinter fire temperature and porosity (b) Ni plate purity, thickness, and sinter firing conditions (c) peak process temperature, time above liquidus and (d) braze alloy washer thickness. ASTM F19 tensile buttons are being used to investigate the above parameters. The F19 geometry permits determination of both joint hermeticity and tensile strength.
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摘要 :
A 472 dimpled ball grid array (D-BGA) package has not been used in past space flight environments, therefore it was necessary to develop a process that would yield robust and reliable solder joints. The process developing assemb...
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A 472 dimpled ball grid array (D-BGA) package has not been used in past space flight environments, therefore it was necessary to develop a process that would yield robust and reliable solder joints. The process developing assembly, inspection and rework techniques, were verified by conducting environmental tests. Since the 472 D-BGA packages passed the above environmental tests within the specifications, the process was successfully developed for space flight electronics.
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摘要 :
Under a cooperative research and development agreement with General Motors Corporation, lead-free solder systems including the flux, metallization, and solder are being developed for high temperature, underhood applications. Six t...
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Under a cooperative research and development agreement with General Motors Corporation, lead-free solder systems including the flux, metallization, and solder are being developed for high temperature, underhood applications. Six tin-rich solders, five silver-rich metallizations, and four fluxes were screened using an experimental matrix whereby every combination was used to make sessile drops via hot plate or Heller oven processing. The contact angle, sessile drop appearance, and in some instances the microstructure was evaluated to determine combinations that would yield contact angles of less than 30(degrees), well-formed sessile drops, and fine, uniform microstructures. Four solders, one metallization, and one flux were selected and will be used for further aging and mechanical property studies.
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摘要 :
Under a cooperative research and development agreement with General Motors Corporation, lead-free solder systems including the flux, metallization, and solder are being developed for high temperature, underhood applications. Six t...
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Under a cooperative research and development agreement with General Motors Corporation, lead-free solder systems including the flux, metallization, and solder are being developed for high temperature, underhood applications. Six tin-rich solders, five silver-rich metallizations, and four fluxes were screened using an experimental matrix whereby every combination was used to make sessile drops via hot plate or Heller oven processing. The contact angle, sessile drop appearance, and in some instances the microstructure was evaluated to determine combinations that would yield contact angles of less than 30(degrees), well-formed sessile drops, and fine, uniform microstructures. Four solders, one metallization, and one flux were selected and will be used for further aging and mechanical property studies.
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摘要 :
The thermal response of fixtured parts in a batch-type brazing furnace can require numerous, time-consuming development runs before an acceptable furnace schedule or joint design is established. Powerful computational simulation t...
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The thermal response of fixtured parts in a batch-type brazing furnace can require numerous, time-consuming development runs before an acceptable furnace schedule or joint design is established. Powerful computational simulation tolls are being developed to minimize the required number of verification experiments, improve furnace throughput, and increase product yields. Typical furnace simulations are based on thermal, fluid flow, and structural codes that incorporate the fundamental physics of the brazing process. The use of massively parallel computing to predict furnace and joint-level responses is presented. Measured and computed data are compared. Temperature values are within 1-2% of the expected peak brazing temperature for different loading conditions. Sensitivity studies reveal that the thermal response is more sensitive to the thermal boundary conditions of the heating enclosure than variability in the materials data. Braze flow simulations predict fillet geometry and free surface joint defects. Dynamic wetting conditions, interfacial reactions, and solidification structure add a high degree of uncertainty to the flow results.
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摘要 :
Temperature-versus-time curves were recorded for various electronic components during pre-tinning, hand soldering, and drag soldering operations to determine the temperature ranges encountered. The component types investigated inc...
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Temperature-versus-time curves were recorded for various electronic components during pre-tinning, hand soldering, and drag soldering operations to determine the temperature ranges encountered. The component types investigated included a wide range of electronic assemblies. The data collected has been arranged by process and will help engineers to: (1) predetermine the thermal profile to which various components are subjected during the soldering operation; (2) decide--on the basis of component heat sensitivity and the need for thermal relief--where hand soldering would be more feasible than drag soldering; and (3) determine the optimum drag solder control parameters. (ERA citation 03:057387)
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摘要 :
Success in a soldering operation depends on the ability of the solder to wet the surfaces of the parts to be joined. Wetting is a function of the cleaning method and is measured by the contact angle. This is the angle that has one...
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Success in a soldering operation depends on the ability of the solder to wet the surfaces of the parts to be joined. Wetting is a function of the cleaning method and is measured by the contact angle. This is the angle that has one of its rays tangent to the liquid surface, the other tangent to the solid surface, and its interior in the liquid. The wetting of a solid vertical wall draws the liquid surface upward in the neighborhood of the wall. The resulting height is a function of both the contact angle and the shape of the vertical wall. This height is easier to measure than the contact angle. A method and a program for determining the contact angle from the height when the vertical wall is cylindrical are described. The method involves solution of a two-point boundary value problem with one of the points infinity. (ERA citation 03:043391)
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