RU2610052C1 - Test object thermal stabilisation apparatus - Google Patents

Abstract

FIELD: physics, instrument-making.

SUBSTANCE: invention relates to electronics and is used to set temperature of integrated microcircuits when testing for resistance to effect of heavy charged particles in vacuum chambers. The apparatus includes a heat-conducting plate for placing a printed-circuit board with a test object, two thermoelectric modules, a cooling unit and two temperature sensors, one of which is placed on the heat-conducting plate, a control unit connected to the modules, temperature sensors and cooling unit. The cooling unit comprises a radiator with fans and a water unit, connected by pipelines through a pump to the radiator. The first and second thermoelectric modules are installed in series between the heat-conducting plate and the water unit. The pipelines are equipped with quick-disconnect airtight valves. The second temperature sensor is placed on the surface of the water unit on the side of the second thermoelectric module.

EFFECT: invention widens the operating temperature range radiation tests of integrated microcircuits, reduces the cost of testing microcircuits due to lower time costs.

3 cl, 2 dwg, 2 tbl, 1 ex

Description

The invention relates to the field of electronics and is used to set the temperature of integrated circuits in tests for resistance to heavy charged particles (TZZ) in vacuum chambers.

According to the classification, the thermal stabilization installation of the test object belongs to the class of electronic devices for the automation of scientific research and is intended to stabilize the temperature of integrated circuits by controlling the power of the heater in order to achieve the temperature level set by the user.

Known two-chamber thermoelectric thermostat containing semiconductor thermoelectric modules, two chilled chambers and a heat exchanger consisting of radiators blown by an air stream formed by a fan [RF Patent 2441703, cl. B01L 7/00, publ. 02/10/2012].

A disadvantage of the known thermostat is the inability to use it under vacuum conditions of the accelerator, since in this case there is no convective heat transfer necessary for the correct operation of the device.

Also known is the LOIP LT-400 series liquid circulation thermostat, designed to accurately maintain temperature both in the bathtub and in the closed loop and containing the intelligent LOIP-ATC control system, high-pressure pump, graphic display, coil, heating element, connector for connection of an external temperature sensor, bidirectional RS-232 interface [Laboratory equipment and instruments catalog of LOIP CJSC, page 18. On the manufacturer’s website http: //loip.r u / upload / iblock / f 3 9 / pribory-loip. pdf. ].

Convection heat exchange with the environment for the operation of this thermostat is not required.

However, this LOIP LT-400 series liquid circulation thermostat has several disadvantages:

- a long time to reach a predetermined temperature regime, which is associated with the need for heating the coolant. The time of the transition process significantly exceeds the pumping time of the vacuum chamber, which increases the time and financial costs of conducting radiation tests;

- large power consumption and bulkiness of the structure, creating inconvenience in the serial conduct of radiation tests;

- the need for a constructive combination of the circulation circuit of the device with the vacuum chamber of the accelerator with the solution of the corresponding tasks of sealing the coolant in the circuit.

Closest to the proposed invention is the installation of thermal stabilization of the test object, including a heat-conducting plate for placing a printed circuit board with the test object, two thermoelectric modules, a cooling unit and two temperature sensors, one of which is located on the heat-conducting plate, a control unit connected to the modules, temperature sensors and a cooling unit, while the latter contains a radiator with a fan [Bakerenkov AS, Belyakov VV, Varlamov NV, Nikitin AM, Pershenkov BC, Shurenkov VV, V olkodaev E.S., Ermolenko T.S. The system of setting and temperature control during experiments at the cyclotron to study single failures in microcircuits. Nuclear physics and engineering. 2011. T. 2. No. 6. S. 502]. The installation is designed for use in vacuum chambers of accelerators.

The applied method of thermal stabilization is based on the balance of the processes of heating the irradiated microcircuit from the local heat-generating element (heater) and heat removal outside the vacuum chamber through the cooling unit.

Known installation of thermal stabilization has the following disadvantages:

the unit has a limited operating temperature range and cannot provide the temperature of integrated circuits during tests lower than 25 ° C. This does not allow to cover the entire temperature range in which the tested chips are used;

the cooling time of thermostabilization equipment when changing the temperature regime is quite long, which leads to an increase in time and financial costs for testing. The transition from a temperature of 125 ° C (upper limit of the operating range) to 25 ° C (lower limit of the operating range) lasts 30 minutes.

The technical task of the invention is to expand the operating temperature range for conducting radiation tests of integrated circuits while reducing the cost of testing circuits by reducing time costs.

This problem is solved by the fact that in the installation of thermal stabilization of the test object, including a heat-conducting plate for placing a printed circuit board with the test object, two thermoelectric modules, a cooling unit and two temperature sensors, one of which is located on the heat-conducting plate, a control unit connected to the modules, sensors temperature and cooling unit, while the latter contains a radiator with fans, the cooling unit is equipped with a water block connected by highways through a pump with a radiator, the first and W swarm thermoelectric modules are arranged in series between the thermally conductive plate and the water-block, line provided with quick-tight valves, the second temperature sensor is disposed on the surface of the water block from the second thermoelectric module.

It is preferable to use thermistors as temperature sensors.

Advantageously, the heat-conducting plate is made of copper.

To expand the operating temperature range, a temperature control system based on thermoelectric modules with a liquid heat sink system has been developed.

Each thermoelectric module can operate both in heating mode and in cooling mode, depending on the polarity of the supply voltage, on which the cooling capacity or heating power depends.

The use of thermoelectric modules as heating elements instead of transistors (as a prototype) allows you to get rid of the radiation vulnerability of the heater. This is due to the fact that bipolar transistors are subject to degradation under the action of ionizing radiation, and thermoelectric modules are practically not susceptible to radiation exposure. This property is especially important, since the thermal stabilization unit is intended for use in radiation tests of integrated circuits. The prototype was used on accelerators with a fairly low particle energy, therefore, radiation degradation of heating transistors was not observed. However, if you use the installation on an ultra-high energy accelerator or on an isotope installation for radiation tests, the degradation of heating transistors will be significant. Thus, the use of thermoelectric modules instead of transistors allows us to ensure the universality of the use of the new thermal stabilization unit.

The use of temperature sensors as temperature sensors, unlike microcircuits (as in the prototype), which are also practically not susceptible to radiation exposure, also allows you to significantly expand the scope of the new thermal device

Thermal stabilization is carried out by controlling the supply voltage of thermoelectric modules in accordance with the readings of a temperature sensor located on a heat-conducting plate and having good thermal contact with the chip under test. Thermal contact is ensured by a heat-conducting plate, which has the lowest possible heat capacity, which allows to reduce the installation transition time between different temperature conditions both during heating and cooling.

In FIG. 1 shows a structural and functional diagram of a thermal stabilization installation.

In FIG. 2 - time dependence of the temperature of the copper plate, the temperature of the sensor of the test board and the water block.

Installation of thermal stabilization of the test object consists of the following blocks and nodes.

The installation includes a heat-conducting plate 1 for accommodating a printed circuit board 2 with the test object 3, the first thermoelectric module 4 and the second thermoelectric module 5 installed in series after the plate 1. Plate 1 is made of copper. It provides thermal contact of thermoelectric modules 4 and 5 with the irradiated test object 3, for example, an integrated circuit mounted on a printed circuit board 2.

The installation comprises a cooling unit, consisting of a radiator 6, fans 7, a water block 8 connected by highways 9 and 10 through a pump 11 to a radiator 7. Highways 9 and 10 are equipped with quick-disconnect tight valves 12 and 13, respectively.

The installation includes temperature sensors, the first external 14 of which is located on the circuit board 2 in the immediate vicinity of the test object 3 to control the quality of thermal contact between the plate 1 and the test object 3, the second 15 on the heat-conducting plate 1, the third 16 on the surface of the water block 8 from the side of the second thermoelectric module 5. Thermistors are used as temperature sensors.

The installation comprises a control unit 17 connected to modules 4 and 5, temperature sensors 14, 15 and 16, a pump 11 and fans 7 of the cooling unit.

Power supply and control of the pump 11 and the fans 7 is carried out by the control unit 17 through a cable having three branches: branches 18, 19 of the fans 7 and the branch 20 of the pump 11.

The heat-conducting plate 1 and thermoelectric modules 4 and 5 are connected to the control unit 17 through a cable 21, a vacuum connector 22 and an internal cable 23 having four branches: a branch of the heat-conducting plate 1, a branch of the first thermoelectric module 4, a branch of the second thermoelectric module 5, and an external connection branch temperature sensor 14.

The power supply to the control unit 17 is carried out by a source 24 of a constant voltage of 12 V with a power of 75 W through a power cable 25, and also by an adjustable voltage source 26 through a power cable 27.

The thermal stabilization installation is controlled by the user using a computer 28, which is connected to the control unit 17 through a serial COM port using a cable 29.

Before use, the functional blocks of the thermal stabilization unit are connected in the following sequence.

The heat-conducting plate 1, thermoelectric modules 4, 5 and the water block 8 are installed in series, together with highways 9, 10 and quick-release valves 12, 13 they are part of the thermostat, which is installed in the vacuum chamber 30 with the flange 31.

Highways 9, 10 through quick-release valves 12 and 13 are connected to the flange 31, which is connected to the radiator 6 and pump 11. As a result, a closed loop is formed for pumping water. Since before the connection both parts of the circuit are filled with water, it is not necessary to fill the water into the circuit when installing the equipment in the vacuum chamber 30. It is also not necessary to drain the water when dismantling the equipment from the vacuum chamber 30 at the end of use. After the water circuit is closed, the flange 31 is hermetically fixed to the surface of the vacuum chamber 30. Further, the remaining functional blocks are interconnected according to FIG. 1 and connect to mains power.

Installation works as follows.

After the installation is turned on, the user using the computer 28 sets the temperature in degrees Celsius, which the thermal stabilization unit must provide for the irradiation session. Computer 28 generates a code corresponding to the set temperature, and transmits it through the COM port via cable 29 to the control unit 17. The control unit 17 reads the temperature sensor 15 located on the heat-conducting plate 1 through cables 21, 23 and the vacuum connector 22. Next in the control unit 17, the measured temperature and the temperature set by the user are compared, the results of which are the correction of the power supplied to the first thermoelectric module 4. The described feedback mechanism provides t temperature stabilization heat conducting plate 1 at a level set by the user.

To ensure thermal stabilization in a wide temperature range, it is possible to use thermoelectric modules 4, 5 in various operating modes depending on the temperature set by the user. Each module 4, 5 can operate in three modes: heating mode, cooling mode and passive mode. The transition from the heating mode to the cooling mode is carried out by changing the polarity of the power supply current of the module. Passive mode corresponds to zero current, i.e. the module is disconnected.

Table 1 shows the temperature ranges specified by the user and the operating modes of thermoelectric modules corresponding to them.

The use of quick-release tight valves 12, 13 made it possible to ensure the convenience of installation and dismantling of thermal stabilization equipment. As a result, all of the above operations are performed within a few minutes, which can significantly increase the performance of the accelerator channel during radiation tests.

Improving the performance of the accelerator channel reduces the cost of testing chips by reducing time costs.

The use of thermoelectric modules 4, 5, installed in series, allowed to significantly expand the operating temperature range of thermostabilization equipment, since each module is independently controlled. In the case of using only one module, a large “dead” temperature range appears near the temperature of the liquid in the heat sink circuit, and the time to establish the temperature increases significantly when approaching the boundaries of the “dead” range. The “dead” range disappears when the first module 4 is turned on in heating mode, and the second 5 in cooling mode.

Standard two-stage thermoelectric assemblies are not suitable for this task, since their cascades are electrically connected in series, which makes it impossible to use them in various modes.

The time for the thermal stabilization equipment to reach the temperature set by the user was reduced by reducing the heat capacity of the heat-conducting copper plate by maximizing its size and also by optimally choosing the boundaries of the temperature ranges for switching the modes of thermoelectric modules. The heating time from room temperature (25 ° C) to maximum (125 ° C) in the developed device is less than 3 minutes, the cooling time from 125 ° C to 25 ° C is less than 5 minutes, and the freezing process from 125 ° C to -40 ° C takes no more than 10 minutes. The confirmatory results of experimental tests of the developed equipment at the U-400M accelerator are given in the example.

Example

The test object was the installation of thermal stabilization of the test object. The installation of thermal stabilization of the test object is designed to set the temperature of integrated circuits in the vacuum chamber of the accelerator when tested for resistance to heavy charged particles.

The thermal stabilization unit and the test board for installing samples of the studied ICs are installed in the vacuum chamber of the U-400M accelerator.

The thermal stabilization control unit is connected to a personal computer with the Windows XP operating system. The air from the vacuum chamber is evacuated. The values are set sequentially: -40 ° C, -25 ° C, 85 ° C, 115 ° C, -40 ° C. The duration of each temperature regime during the tests was more than 7 minutes. Depending on the time during transients, the temperature of the heat-conducting plate 1, measured by the sensor 15, the temperature of the sensor 14 of the test board 2 and the temperature of the water block 8 (hot side), measured by the sensor 16, are presented in FIG. 2.

The pressure in the vacuum chamber after 7 minutes after setting each of these electrical modes is determined, the results are listed in table 2.

The proposed technical solution allows radiation tests of integrated circuits at the U400 and U400M accelerators in various temperature conditions, and also provides the opportunity to study the temperature dependences of physical processes that occur in integrated circuits when exposed to heavy charged particles.

A characteristic feature of this method is the high speed of the thermal stabilization unit and the high efficiency of active cooling, which allows setting the temperature of high-power integrated circuits during radiation tests.

Based on the foregoing, it is proposed to use the installation of thermal stabilization of the test object during radiation tests of integrated circuits for resistance to the effects of heavy charged particles in the vacuum chambers of the U400 and U400M accelerators.

The final technical result of the claimed invention is the ability to set and control the temperature of integrated circuits during serial radiation tests of electronic products with the aim of their certification for use in electronic equipment for space purposes.

Claims (3)

1. Installation of thermal stabilization of the test object, including a heat-conducting plate for placing a printed circuit board with the test object, two thermoelectric modules, a cooling unit and two temperature sensors, one of which is located on the heat-conducting plate, a control unit connected to modules, temperature sensors and a cooling unit, the latter contains a radiator with fans, characterized in that the cooling unit is equipped with a water block connected by highways through a pump with a radiator, the first and second thermoelements ctric modules are installed in series between the heat-conducting plate and the water block, the lines are equipped with quick-disconnect tight valves, and the second temperature sensor is located on the surface of the water block from the side of the second thermoelectric module. 2. The installation of thermal stabilization of the test object according to claim 1, characterized in that thermistors are used as temperature sensors. 3. Installation of thermal stabilization of the test object according to claim 1, characterized in that the heat-conducting plate is made of copper.

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