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Reliability modeling of soldered interconnections
1412
World Abstracts on Microelectronics and Reliability
turn-off thyristors (GTOs), and depletion-mode transistors and thyristors. Electrically and optically triggered devices are included in the discussion. Also, there is a brief description of new developments for devices built from advanced semi-conductor materials such as GaAs, SiC, and diamond, including high voltage intrinsic switches.
Reliability modeling of soldered interconnections. JAMES F. PROSSER and NICHOLAST. PANOUSIS. IEEE Transactions on Components, Hybrids, and Manufacturing Technology, 15(6), 1046 (1992). This paper describes the results of work to determine the minimum solder height that would produce a satisfactory joint in an electronic assembly used in IBM disk drives. Solder pads with heights ranging from 20 to 160 pm were produced by varying the solder deposition process. After joints were made using the standard soldering process, the joint strengths were measured by pulling the wire at an angle of 45 ° and measuring the force required to either break the wire (wire breaks) or pull the wire out of the solder (wire peels). A figure of merit for the solder process is defined as the fraction of wire peels. A key part in this paper is the use of a generalized regression model to correlate this figure of merit to solder height. This allows interpolation of the data, calculation of confidence intervals, and a check of the validity of process control plans. The model is used to determine the minimum solder height, and to establish a sampling plan to monitor production. Constitutive relations for tin-based solder joints. ROBERT DARVEAUX and KING SHUK BANERJI. I E E E
Transactions on Components, Hybrids, and Manufacturing Technology, 15(6), 1013 (1992). This paper presents extensive data on 62Sn36Pb2Ag, 60Sn40Pb, 96.5Sn3.5Ag, 97.5Pb2.5Sn, and 95Pb5Sn solder. All of the data were collected on actual soldered assemblies to properly account for the effects of grain size and intermetallic compound distribution. Tensile and shear loading were employed in the strain rate range between 10-8 and 10-1 s-l and the temperature range between 25 and 135°C. It is remarkable to note that all of the data can be fit to the same general form of constitutive relations; i.e., only the constants depend on the solder alloy. The derived constitutive relations are used to predict solder joint response under thermal cycling. Based on the calculated hysteresis loops, it is apparent that each solder will have a different acceleration factor between field use cycling and accelerated test cycling. A statistical method for obtaining the factors in electronic-component reliability-prediction models. ZHONGSEN YANG and HAZEM RAAFAT. IEEE Transactions on Reliability, 41(4), 554 (1992). According to US Mil-Hdbk-217, the failure rate of most electronic components can be predicted as 2p = 2 b ' n ~ ' n 2 . . . . ' n ~ . The accuracy of prediction
depends on the accuracy of "~'band n~. Therefore, it is very important to obtain and amend the values of 2b and hi. This paper presents a statistical method of obtaining 2b and hi. The method is based on large quantities of field data. The more current the field data are, the more accurate the values of each level of 2b and ni. Using the values of each level of 2b and ni, one can use the models in US Mil-Hdbk-217 to predict the life of electronic products. The method can also be used to verify the present values of each level of 2b and n~, and to provide the basis of further amendment.
Gaussian parametric failure-rate model with application to Quartz-Crystal device aging. A. A. FEINBERG. IEEE Transactions on Reliability, 41(4), 565 (1992). A model for predicting parametric failure rate for a time-dependent normal (Gaussian) distribution is obtained in closed form. The model can be applied to any device parameter that can be modelled by a normal distribution when the parameter time-dependence is known. To use the model for obtaining parametric failure rates, it is necessary only to model the parameter distribution over time with a parametric failure limit. The model is applied to the aging law of quartz surface-acoustic-wave (SAW) devices. The parametric failure rate for the 295.6 MHz SAW filters was obtained at 75°C (using the model) based on aging data taken on sample population of 80 SAW filters. The frequency and phase parameters of the population were characterized over time using an accelerated test. The example illustrates how the mean and standard deviation can be characterized over time for the parametric distribution. Then using these results for the representative lot, the model predicts the population's parametric failure rate at use conditions. These predictions are based on defined limits for parametric stability. Such requirements are generally defined by customer needs. This application shows that: (a) when a characteristic parameter for a population of devices being investigated is normally distributed and ages in log(time), then the failure rate has a Iognormal form in time; (b) a sample standard deviation for time dependent parameters is also time dependent. The concepts of the model are straightforward, and the methodology can be applied whenever a device aging-law is known. Increased reliability of drypumps due to process related adaptation and prefailure warning. R. BAHNEN and M. KUHN. Vacuum, 44(5-7), 709 (t993). Semiconductor production requires high reliability without unscheduled downtime of the vacuum equipment used, as well as low maintenance costs. It is necessary to adapt the pump to different process conditions to avoid particle accumulation or solid formation inside the pump. The design of the pump permits operation under various process conditions without any interruption or additional cleaning cycles. All parameters important for the operation of the pump and its
World Abstracts on Microelectronics and Reliability
turn-off thyristors (GTOs), and depletion-mode transistors and thyristors. Electrically and optically triggered devices are included in the discussion. Also, there is a brief description of new developments for devices built from advanced semi-conductor materials such as GaAs, SiC, and diamond, including high voltage intrinsic switches.
Reliability modeling of soldered interconnections. JAMES F. PROSSER and NICHOLAST. PANOUSIS. IEEE Transactions on Components, Hybrids, and Manufacturing Technology, 15(6), 1046 (1992). This paper describes the results of work to determine the minimum solder height that would produce a satisfactory joint in an electronic assembly used in IBM disk drives. Solder pads with heights ranging from 20 to 160 pm were produced by varying the solder deposition process. After joints were made using the standard soldering process, the joint strengths were measured by pulling the wire at an angle of 45 ° and measuring the force required to either break the wire (wire breaks) or pull the wire out of the solder (wire peels). A figure of merit for the solder process is defined as the fraction of wire peels. A key part in this paper is the use of a generalized regression model to correlate this figure of merit to solder height. This allows interpolation of the data, calculation of confidence intervals, and a check of the validity of process control plans. The model is used to determine the minimum solder height, and to establish a sampling plan to monitor production. Constitutive relations for tin-based solder joints. ROBERT DARVEAUX and KING SHUK BANERJI. I E E E
Transactions on Components, Hybrids, and Manufacturing Technology, 15(6), 1013 (1992). This paper presents extensive data on 62Sn36Pb2Ag, 60Sn40Pb, 96.5Sn3.5Ag, 97.5Pb2.5Sn, and 95Pb5Sn solder. All of the data were collected on actual soldered assemblies to properly account for the effects of grain size and intermetallic compound distribution. Tensile and shear loading were employed in the strain rate range between 10-8 and 10-1 s-l and the temperature range between 25 and 135°C. It is remarkable to note that all of the data can be fit to the same general form of constitutive relations; i.e., only the constants depend on the solder alloy. The derived constitutive relations are used to predict solder joint response under thermal cycling. Based on the calculated hysteresis loops, it is apparent that each solder will have a different acceleration factor between field use cycling and accelerated test cycling. A statistical method for obtaining the factors in electronic-component reliability-prediction models. ZHONGSEN YANG and HAZEM RAAFAT. IEEE Transactions on Reliability, 41(4), 554 (1992). According to US Mil-Hdbk-217, the failure rate of most electronic components can be predicted as 2p = 2 b ' n ~ ' n 2 . . . . ' n ~ . The accuracy of prediction
depends on the accuracy of "~'band n~. Therefore, it is very important to obtain and amend the values of 2b and hi. This paper presents a statistical method of obtaining 2b and hi. The method is based on large quantities of field data. The more current the field data are, the more accurate the values of each level of 2b and ni. Using the values of each level of 2b and ni, one can use the models in US Mil-Hdbk-217 to predict the life of electronic products. The method can also be used to verify the present values of each level of 2b and n~, and to provide the basis of further amendment.
Gaussian parametric failure-rate model with application to Quartz-Crystal device aging. A. A. FEINBERG. IEEE Transactions on Reliability, 41(4), 565 (1992). A model for predicting parametric failure rate for a time-dependent normal (Gaussian) distribution is obtained in closed form. The model can be applied to any device parameter that can be modelled by a normal distribution when the parameter time-dependence is known. To use the model for obtaining parametric failure rates, it is necessary only to model the parameter distribution over time with a parametric failure limit. The model is applied to the aging law of quartz surface-acoustic-wave (SAW) devices. The parametric failure rate for the 295.6 MHz SAW filters was obtained at 75°C (using the model) based on aging data taken on sample population of 80 SAW filters. The frequency and phase parameters of the population were characterized over time using an accelerated test. The example illustrates how the mean and standard deviation can be characterized over time for the parametric distribution. Then using these results for the representative lot, the model predicts the population's parametric failure rate at use conditions. These predictions are based on defined limits for parametric stability. Such requirements are generally defined by customer needs. This application shows that: (a) when a characteristic parameter for a population of devices being investigated is normally distributed and ages in log(time), then the failure rate has a Iognormal form in time; (b) a sample standard deviation for time dependent parameters is also time dependent. The concepts of the model are straightforward, and the methodology can be applied whenever a device aging-law is known. Increased reliability of drypumps due to process related adaptation and prefailure warning. R. BAHNEN and M. KUHN. Vacuum, 44(5-7), 709 (t993). Semiconductor production requires high reliability without unscheduled downtime of the vacuum equipment used, as well as low maintenance costs. It is necessary to adapt the pump to different process conditions to avoid particle accumulation or solid formation inside the pump. The design of the pump permits operation under various process conditions without any interruption or additional cleaning cycles. All parameters important for the operation of the pump and its