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Thermocompression bonding of external package leads on integrated circuit substrates
WORLD ABSTRACTS ON MICROELECTRONICS AND R E L I A B I L I T Y
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internal feedback. The frequency response of the circuit with the bias-diode is superior to that without the bias-diode. The current gain of the circuit can be controlled by appropriate design of active or passive elements. The experimental results using discrete components agree with the analysis.
Thermocompression bonding of external package leads on integrated circuit substrates. V. P. BOLCAR,IEEE Tram. ED-15, September (1968), p. 651. A new technique for attaching external package leads to metallized substrates is presented. Gold-plated copper lead frames and gold-plated headed leads of various compositions are thermocompression bonded to metallized alumina substrates. The generated patterns on the substrates consist of an evaporated layer of gold over an evaporated layer of titanium. The leads are bonded simultaneously to form gold diffusion bonds between the leads and the metallized substrate. The lead frames are stamped from 0.005 in. and 0.010 in. thick copper. The headed leads range in size from 0.017 in. in diameter to 0.025 in3 The various problems encountered in the development of this technique and their related solutions will be discussed. The bonding tool consists of a base for positioning the substrate and a bonding tip which applies the necessary pressure and temperature to produce a bond. The base and bonding tip for lead frames can compensate for camber and nonuniform thickness ill the ceramic while the base and bonding tip for headed leads are noncompensating. The various parameters of bonding time, bonding temperature, bonding force and bond strengths will be presented. In addition, hermetic seal evaluations will be discussed. A comparative cost analysis will be made between attaching leads individually by welding versus attaching all package leads simultaneously by the thermocompression bonding technique. This investigation has opened additional avenues toward determining the full scope and capability of thermocompression bonding in an area previously dominated by brazing and the sealing of metal to glass and/or ceramics. Air-gap isolated microcircuits-beam-lead devices. W. C. ROSVOLD,W. H. LEGAl" and R. L. HOLDEN,IEEE Tram. ED-15, September (1968), p. 640. The comparison of air-gap isolated integrated circuits with conventionally fabricated circuits shows the advantage of the "beam-lead concept". Utilizing the anisotropic etching properties of single crystalline silicon in the (100) direction combined with the vapor deposition of SiOa at low temperatures, discrete silicon mesas for the active areas of the device are formed. Computer simulation methods applied to hybrid integrated circuits. R. COCHAIN,J. CARON and P. DIERICK,Onde Elect. 48, September (1968), p. 773. (In French.) Some results obtained by computer in electronic circuits design are exposed. At first one will find the rule followed in the choice of objectives, then the realized software structure. Problem of component mathematical models and their parameters measurements is then treated and some practical application examples are given. Designing with diff-amp and op-amp ICs. R. SEYMOURand L. BROWN,EEE 17, No. 4, April (1969), p. 59. This article describes four applications, two using the Signetics 516 differential amplifier and two for the Signetics 5709 operational amplifier. The first two are a one-shot multivibrator with a long time constant, to provide ramps with slow build-up (0.1 to 1 sec), and a triggerable ramp generator. The two op-amp applications are on audio pre-amp with both tape and phono equalizing compensations that can be switched in, and another audio amplifier with bass-treble controls. Controlled collapse reflow chip joining. L. F. MILLER,I B M J. Res. Dev. 13, No. 3, May (1969), p. 239. Solder reflow connection of semiconductor devices to substrates has been shown to be a reliable, effective and readily automated technique. Rigid copper spheres, which remain rigid during solder reflow, have been used successfully for some time as a major element of the contact joint. However, to expand the capability of such joints to larger devices such as multiple-transistor chips in hybrid components, ductile metallic joining pads can be used on the devices instead of the copper spheres to reduce mechanical strains and permit multi-pad devices to make proper contact to module lands during reflow. This paper describes a technique that prevents these solder pads from collapsing and permits large-scale production. Termed "controlled collapse", the method is based on limiting the solderable area of the substrate lands and chip contact terminals so that surface tension in the molten pad and land solder
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internal feedback. The frequency response of the circuit with the bias-diode is superior to that without the bias-diode. The current gain of the circuit can be controlled by appropriate design of active or passive elements. The experimental results using discrete components agree with the analysis.
Thermocompression bonding of external package leads on integrated circuit substrates. V. P. BOLCAR,IEEE Tram. ED-15, September (1968), p. 651. A new technique for attaching external package leads to metallized substrates is presented. Gold-plated copper lead frames and gold-plated headed leads of various compositions are thermocompression bonded to metallized alumina substrates. The generated patterns on the substrates consist of an evaporated layer of gold over an evaporated layer of titanium. The leads are bonded simultaneously to form gold diffusion bonds between the leads and the metallized substrate. The lead frames are stamped from 0.005 in. and 0.010 in. thick copper. The headed leads range in size from 0.017 in. in diameter to 0.025 in3 The various problems encountered in the development of this technique and their related solutions will be discussed. The bonding tool consists of a base for positioning the substrate and a bonding tip which applies the necessary pressure and temperature to produce a bond. The base and bonding tip for lead frames can compensate for camber and nonuniform thickness ill the ceramic while the base and bonding tip for headed leads are noncompensating. The various parameters of bonding time, bonding temperature, bonding force and bond strengths will be presented. In addition, hermetic seal evaluations will be discussed. A comparative cost analysis will be made between attaching leads individually by welding versus attaching all package leads simultaneously by the thermocompression bonding technique. This investigation has opened additional avenues toward determining the full scope and capability of thermocompression bonding in an area previously dominated by brazing and the sealing of metal to glass and/or ceramics. Air-gap isolated microcircuits-beam-lead devices. W. C. ROSVOLD,W. H. LEGAl" and R. L. HOLDEN,IEEE Tram. ED-15, September (1968), p. 640. The comparison of air-gap isolated integrated circuits with conventionally fabricated circuits shows the advantage of the "beam-lead concept". Utilizing the anisotropic etching properties of single crystalline silicon in the (100) direction combined with the vapor deposition of SiOa at low temperatures, discrete silicon mesas for the active areas of the device are formed. Computer simulation methods applied to hybrid integrated circuits. R. COCHAIN,J. CARON and P. DIERICK,Onde Elect. 48, September (1968), p. 773. (In French.) Some results obtained by computer in electronic circuits design are exposed. At first one will find the rule followed in the choice of objectives, then the realized software structure. Problem of component mathematical models and their parameters measurements is then treated and some practical application examples are given. Designing with diff-amp and op-amp ICs. R. SEYMOURand L. BROWN,EEE 17, No. 4, April (1969), p. 59. This article describes four applications, two using the Signetics 516 differential amplifier and two for the Signetics 5709 operational amplifier. The first two are a one-shot multivibrator with a long time constant, to provide ramps with slow build-up (0.1 to 1 sec), and a triggerable ramp generator. The two op-amp applications are on audio pre-amp with both tape and phono equalizing compensations that can be switched in, and another audio amplifier with bass-treble controls. Controlled collapse reflow chip joining. L. F. MILLER,I B M J. Res. Dev. 13, No. 3, May (1969), p. 239. Solder reflow connection of semiconductor devices to substrates has been shown to be a reliable, effective and readily automated technique. Rigid copper spheres, which remain rigid during solder reflow, have been used successfully for some time as a major element of the contact joint. However, to expand the capability of such joints to larger devices such as multiple-transistor chips in hybrid components, ductile metallic joining pads can be used on the devices instead of the copper spheres to reduce mechanical strains and permit multi-pad devices to make proper contact to module lands during reflow. This paper describes a technique that prevents these solder pads from collapsing and permits large-scale production. Termed "controlled collapse", the method is based on limiting the solderable area of the substrate lands and chip contact terminals so that surface tension in the molten pad and land solder