Showing papers on "Junction temperature published in 1986"

Optimal Finned Heat Sinks

Abstract: In a multi-board computer system, the volume allocated for heat removal is often a significant fraction of the total system volume. Cooling requirements can thus impact performance, reliability, cost, acoustic noise, and floorspace. This work addresses the volume costs or space requirements for removing heat with optimally designed finned heat sinks. Simple formulas applicable to both gas and liquid cooling problems provide upper bounds on the thermal resistance of an optimal heat sink, without explicitly designing the part. Conservative junction temperature estimates can thus be made without detailed design.

Integrated circuit speed controller

Abstract: A speed control circuit made by using CMOS processes is capable of handling high voltage and high current loads. The output of the speed control circuit is provided by a power field effect transistor. Current sensing means are provided to generate a fault signal in case an over current condition occurs. The junction temperature of the power field effect transistor is also monitored to provide an over temperature condition if the temperature of the junction of the power field effect transistor exceeds a predetermined value. A ramping generator is used to set a latch which controls the operation of the power field effect transistor. A speed control signal is compared against the ramping signal provided by the ramp generator and resets the latch in order to provide speed control.

Semiconductor junction temperature emulator

Abstract: The present device includes a resistor network wherein the values of the resistors are chosen such that the heat generated by current passing through the resistors will be substantially equal to heat generated at a semiconductor junction which is to be cooled. The present device further includes a heat sink which is substantially identical to the heat sink employed to withdraw heat from the semiconductor junction to be cooled. Accordingly, the present device provides heat which is identical to the heat generated at the semiconductor junction and which heat remains ambient to the semiconductor junction to be cooled. The present device further includes a sensor which converts temperature to an electrical signal and which is located substantially in the center of the resistor network and at a distance from the heat sink that approximates the position of the semiconductor junction from its heat sink. The temperature to electrical signal sensor generates a control electrical signal whose value is commensurate with the temperature of the air at the location of the temperature to electrical signal sensor and that temperature is substantially identical to the temperature at the semiconductor junction. The control electrical signal is employed by a servo circuit to drive an air fan to move air over the semiconductor junction to cool it. However, the air passed over the junction is limited to the quantity necessary to prevent damage as compared to a maximum airflow. Hence, there is a reduction in acoustical noise and a saving in energy.

Method and apparatus for determination of junction-to-case thermal resistance for a hybrid circuit element

Abstract: A method and apparatus for determining the junction-to-case thermal resistance, θ jc , of a solid-state hybrid circuit element 38. First, the temperature coefficient, T c , of the voltage across the junction is determined with a small calibration current flowing through the junction. Digital multimeters 12 and 28 are used to measure the junction voltage and current, respectively. Next, more power is applied and the total power, P T , dissipated by the hybrid circuit element 38 is determined from values of the applied voltage and current measured with digital multimeters 12 and 14. The case of the hybrid element is kept at a constant temperature by a heat sink arrangement and the junction is allowed to reach thermal equilibrium at the higher power level. Finally, the increase in power to the hybrid element is removed and the change in junction voltage drop, ΔV BE , between low-power operation and high-power operation is determined using a storage oscilloscope 30. The junction-to-case thermal resistance, θ jc , is given by the quotient of ΔV BE and the product of P T and T c .

Monolithic temperature compensated voltage-reference diode and method for its manufacture

Abstract: An improved monolithic, temperature compensated voltage- reference diode is realized by creating a tub (17) of epitaxial semiconductor material in a substrate of opposite conductivity type and creating a voltage reference junction (26) at a surface of the tub. The junction (18) between the tub and the substrate forms the forward-biased, temperature compensating junction of the device. The dopant concentration is varied during growth of the epitaxial material to provide a relatively low resistivity at the voltage-reference junction and a higher resistivity at the temperature compensating junction. The method described offers significant improvement over prior methods of manufacturing such devices in the area of cost and reliability.

Low-power temperature detector and rate of temperature change detector

Abstract: A temperature detection switch and a “rate of temperature change” detection switch are designed by using the dependence of the inverse saturation current of the p-n junction on temperature. This current is compared to the constant reference current in the case of the temperature detector or, for the detector of the rate of temperature change, to the inverse saturation current of another p-n junction, having different thermal time constant and different junction area. Relying upon the shape of the static characteristic of the constant reference current source, realized in a usual manner, and the inversely polarized p-n junction, the low-power current comparator is realized by a simple series connection of the current sources, with the supply voltage applied at the end points and the detector output voltage derived from the midpoint. Besides describing the operating principle, the paper contains the analysis of the thermal model of the switches and the accuracy investigations. The design criteria are experimentally confirmed. Due to their accuracy (0.1°C), simplicity, and extremely low power consumption (supply current is less than 10 μA), present detectors are especially suitable for applications in fire alarms.

Reactive power compensating device

Abstract: PURPOSE:To make it possible to supply delayed reactive force while protecting an element by stopping down controlling angle when element junction temperature of a thyristor switch and voltage become above specified values and releasing the stop control when the values become below specified values. CONSTITUTION:When system voltage VP rises, thyristor junction temperature T rises. Rise of voltage VP is judged by a level detector 7 and a signal 1 is outputted. When temperature T; arrives at a specified value, a signal 1 is outputted by a level detector 6. Consequently, a AND circuit 1 becomes one output, an FF 10 is set and control of 90 deg. is selected by a control angle selecting circuit 11. Thereby, voltage between poles of a thyristor switch becomes almost 0. When restored to normal system voltage, temperature Tj lowers. When temperature Tj becomes lower than a specified value and voltage VP also becomes lower than a specified value, output of a NOR circuit 9 becomes 1 and the FF 10 is reset. Thus, it is returned to normal control by controlling angle from a controlling device 5 through the circuit 11.

Electronic temperature equalizer

Abstract: An electronic circuit has been devised for precisely controlling the temperature of one zone in response to a change in temperature in another zone. Two sensors, one in each zone, are wired in opposing polarity so as to emit a signal when a temperature imbalance occurs. The circuit is designed to actuate a temperature controller in response to the signal. One application for the device is the establishment of adiabatic conditions for a reaction by controlling the temperature of the zone surrounding the reaction vessel to coincide with that within the vessel.

Package for semiconductor device

Abstract: PURPOSE:To directly cool a junction by providing a mount for mounting a semiconductor device and electronic cooling means for contacting a heat absorber with the mount. CONSTITUTION:An electronic cooler 7 is composed of an electronic cooling element 18 utilizing Peltier effect, the element 18 is formed of an N type semiconductor 30 and a P type semiconductor 32 connected by a metal plate 34, and when a current I is flowed from the semiconductor 30, the plate 34 absorbs heat by the Peltier effect. A plurality of the elements 18 are connected in series, and the both ends of the row of the elements 18 are connected with a power terminal 11 and a mounting terminal 12. When a power voltage VDD is applied to the terminal 11 and the terminal 12 is mounted, the current I is flowed to the elements 18 of the cooler 7 to reduce the temperature of a heat absorber, a bed 9 contacted with the absorber 8 is cooled to absorb the heat generated at a semiconductor device 4. Thus, the junction temperature of the device 4 is suppressed to low value.

Controller of generator

Abstract: A voltage regulator (2) for a generator (1) wherein a switching device (10) connected in series to the field coil (4) of the generator is adapted to be controlled in accordance with an output voltage of the. generator and the ambient temperature at the voltage regulator so as not to exceed the junction temperature limit value of the switching device (10).

Characterization of Diode Laser Mountings by only Electrical Measurements

Abstract: Light power and laser characteristics of diode lasers are strongly depending on the laser chip temperature. The heat produced by current flow through a diode laser results in a temperature rise in the active region relative to the heat sink. The maximum temperature rise is depending on the pulse length at short /shorter than 10 /usec / pulses. The characteristics and quality of laser chip mounting and case can be tested by measuring the voltage of diode laser at current pulses with finite rising and falling time.

Testing method for semiconductor device

Abstract: PURPOSE:To test moisture resistance by reducing the decrease to the relative temperature to a substantially neglegible degree, by a method wherein powder is impressed for a shorter time than the thermal time constant the sample to be tested has, which sample is then left stand until the junction temperature becomes much closer to the ambient temperature, and this operation is repeated. CONSTITUTION:A DUT1 is installed in a constant-temperature constant-moisture bath 2 and connected to a pulse power source 3: the ON-time of this power source 3 must be set at a shorter time than the time constant of the DUT1. The next OFF-time is selected at the minimum value of times when the junction comes much closer to the ambient temperature. For example, in the case of the TV signal processing bi-polar IC with a 48-pin DIP type container, the ON-time can be approx. 10ms-1s, and the OFF-time approx. 100ms-5s. The variation with time in relative moisture in the junction neighborhood at this time shows nearly a constant relative moisture as shown by a graph A. Such a measurement of moisture resistance by keeping the actual atmosphere at the IC constant enables the test of moisture resistance of high reliability.

Optimum Design of CW 94 GHz Si DDR IMPATT Sources

Abstract: This paper describes a theoretical and experimental approach to design optimum high power high efficiency CW IMPATT sources in the 94 GHz window. Particular emphasis is placed on junction temperature rise in order to achieve reliable high power operation. Secund order parameters such as noise and locking bandwidth are also considered.

Diodes and Power Transistors

Abstract: A knowledge of quantum mechanics and solid-state physics is necessary background for comprehending the details of the operation of semiconductor devices. However, for this text, it is sufficient to have a general understanding of transistor behavior. The following description is intended to present a physical explanation of bipolar transistor operation, which will provide the basis for power transistor application limitations and unique characteristics [1], [2].

Applications of heat pipes to cool PWBS and hybrid microcircuits

Abstract: Some of the advanced thermal management techniques used to reduce operating junction temperature under extreme environmental temperature conditions are discussed. Heat pipes in actual electronic packaging applications, and those under development, are discussed. Performance characteristics of heat pipes are given, and examples are described of how thermal problems in electronic packaging are solved through the use of heat pipes.

High-power cw operation over 480 mW on five-stripe phased-array lasers assembled by a new junction-down mounting

Abstract: The phased-array laser is the most promising candidate to give high output power over 100 mW. At high-power cw operation, the output power-current characteristics tend to saturate because the Junction temperature rises due to the high current. Hence the junction-down (J-down) mounting is important in achieving high-power cw operation. Generally, soft solders such as In alloys have been employed for the J-down assembly to avoid the mechanical stress between laser chip and heat sink. These solders, however, have many disadvantageous effects on reliability, such as solder migration into the laser crystal or formation of whisker.1,2