RU2528392C1 - Ic cooling device - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in a IC cooling device operated on Peltier effect principle, an aluminium heat splitter is glued to the IC ceramic case and a cooling semiconductor unit using the Peltier effect is glued on the splitter. The IC case bottom is at the same time a top heat transfer path of the cooling semiconductor unit, soldering of dice to the substrate and of the substrate with the case bottom (upper heat transfer path of a TEM), upper heat transfer path with one surface of semiconducting legs of p- and n-type is carried out under the temperature which is by 20-25°C lower than the temperature of soldering of the other surface of semiconducting legs to the lower heat transfer path; the semiconducting legs are set between the heat transfer paths so that all hot surfaces are in contact with one heat transfer path and all cold surfaces - with the opposite path and they are connected into a common electric circuit by metallisation with the said circuit being connected to a power source, a thermocouple is fixed to the IC case to control its temperature, the thermocouple is connected to the power source's polarity switching unit to stabilise the temperature (for heating or cooling).

EFFECT: increased heat transfer from the dice to the case, simplified assembly process with the usage of heat sinks on the Peltier effect basis.

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Description

The invention relates to the field of electronics and is intended for heat removal from IS, VLSI, power modules, electronic equipment units (REA), etc.

The thermal regime of semiconductor products (PPI) to a large extent determines their reliability. Statistics show that in 60% of cases the cause of failure of electronic equipment is a violation of the thermal regime of both the device as a whole and its individual elements.

The development of methods and devices for heat removal from PPI is an urgent task, the solution of which is aimed at the efforts of all specialists working in the field of semiconductor microelectronics.

There are various methods of heat removal from IS, VLSI, power modules, REA units, etc.

Known heat sink [1], which is a device made of aluminum alloy for heat dissipation using a Peltier thermoelectric element, which has the shape of a cube and is mounted to the cooled device with the bottom surface. Parallel to the lower mounting surface, the volume of the cube is drilled through in several places in mutually perpendicular directions. To improve the air ventilation of the device, the through holes communicate with vertical openings facing the top surface of the cube. At the same time, several heat pipes were introduced into the cube volume, filled to 15-18% of its volume with working coolant.

The main disadvantage of this heat sink is the complexity of the technology for assembling a cooling semiconductor unit to a cooled microelectronic product.

The main advantages of constructing cooling and thermal stabilization systems using thermoelectric modules (TEM) based on the Peltier effect are [2]:

small dimensions (3.4 mm × 3.4 mm) and weight (less than 2 g) determine the absence of alternative solutions for thermal stabilization and cooling in micro- and photoelectronics;

high reliability, for example, the KRIOTERM company guarantees for its TEMs an average time between failures of at least 200,000 hours;

high cooling capacity per unit weight and volume - up to 150 W / g and up to 100 W / cm ² ;

the possibility of smooth and high-precision temperature control;

low inertia, quick transition from cooling to heating mode.

TEMs based on the Peltier effect include more than 250 items with standard sizes (40 mm × 40 mm, 30 mm × 30 mm, 15 mm × 15 mm, etc.), as well as specially designed from micromodules to modules with dimensions of 62.5 mm × 62.5 mm.

The main disadvantage of using TEM is the reduction of heat transfer from IS, VLSI, power modules and REA units to the cooler.

It is known [3] that power modules are attached to the cooler using screws, rivets, spring washers, etc. For the best heat transfer from the base to the cooler, heat-conducting pastes and special gaskets made of aluminum foil, thin gaskets made of heat-conducting but insulating material (kapton) are used polyamide film). The use of special heat-conducting pastes and gaskets is necessary to smooth out the irregularities of the connected surfaces. The greater the surface roughness, the thicker the auxiliary layer should be.

Thus, these factors complicate the PPI assembly technology.

The closest in technical essence to the claimed invention is an IC cooling device [4], which consists in the fact that an aluminum heat dissipator is glued to the IC in a ceramic case, and a cooling semiconductor unit using the Peltier effect is glued to it. A radiator is attached to the upper hot surface of the cooling unit, to which a fan is screwed. To assemble the device, a heat-conducting adhesive film is used.

The main disadvantage of this device is the decrease in heat removal from the crystal to the housing due to the use of an intermediate adhesive film. In addition, the use of a radiator and a fan complicates the assembly technology of the IC.

The problem to which the claimed solution is directed is to increase the heat sink from the crystal to the body; simplification of PPI assembly technology using heat sinks based on the Peltier effect.

This task is achieved in that in an IC cooling device based on the use of the Peltier effect, on which an aluminum heat dissipator is glued to the IC in a ceramic case, and a cooling semiconductor block using the Peltier effect, characterized in that the base of the IC case is simultaneously the upper heat transfer cooling semiconductor unit, while soldering crystals to the substrate, the substrate with the base of the body (upper heat transfer TEM), the upper heat transfer with one surface of the floor p- and n-type conductive branches occurs at a temperature of 20-25 ° C below the soldering temperature of the other surface of the semiconductor branches to the lower heat transfer, with the semiconductor branches placed between the heat transitions in such a way that all hot surfaces are in contact with one heat transfer, and all cold - with the opposite and with the help of metallization, they are connected into a single electrical circuit that is connected to a power source, a thermocouple is attached to it to control the temperature of the IP housing, and to stabilize The temperature (heating or cooling) of the thermocouple is connected to the polarity switching unit of the power source.

Comparison of the inventive IC cooling device with other devices [1-4] of the prior art also did not reveal the signs claimed in the characterizing part of the formula.

The invention is illustrated by drawings, which schematically depict:

figure 1 - crystal IP;

in FIG. 2 - a substrate made of DBC ceramics;

in FIG. 3 - the base of the housing IP (upper heat transfer TEM);

in FIG. 4 - lower TEM heat transfer with n- and p-type semiconductors before assembly;

figure 5 - lower heat transfer TEM with semiconductors n- and p-type after assembly;

Fig.6 is a diagram of the Assembly of the cooling device IC;

Fig.7 is a General view of the cooling device IC with a cooling semiconductor unit (TEM).

The cooling device IC is implemented according to the scheme (figure 1). Ready-made semiconductor crystals 1 arrive at the assembly, on the front surface of which there are contact pads 2, for example, in the form of aluminum metallization for the subsequent installation of internal leads, and on the soldered surface of the crystals 1, multilayer film metallization 3, for example, Ti, Ni-Ti, Ag .

Figure 2 presents the substrate 4 of DBC-ceramics (Direct Bonding Copper), which acts as an electrically insulating and heat-conducting layer between the crystal and the body. The DBC ceramic (Al ₂ O ₃ or AlN) on both sides has a metallization 5 obtained by direct (diffusion) splicing with a copper foil on which a nickel coating is applied and by any known method solder 6, for example, 70Bi / 30Sn alloy (in% ) having a melting point of 175 ° C. Metallization 5 with solder 6 of the lower surface of the substrate 4 is continuous, and the upper - in the form of pads for soldering crystals 1.

Figure 3 shows the base of the housing 7, which is simultaneously the upper heat transfer TEM. The technology for applying metallization 5 is the same as for the substrate 4 (figure 2). However, metallization 5 on the upper surface of the base of the housing 7 is continuous, and the bottom in the form of contact pads for soldering p-type and n-type semiconductor branches of TEM, with solder 6 applied to the contact pads.

The use of the IC housing as the upper heat transfer of the TEM increases the heat transfer from the crystal to the housing.

Figure 4 presents the lower heat transfer 8 TEM, which is manufactured separately and consists of the same material and has the same metallization 5 as the base of the housing 7 (upper heat transfer). However, metallization 5 of the contact pads is coated with solder 9, for example, 80Bi / 20Sn alloy (wt.%) Having a melting point of 200 ° C. On the semiconductor branches of p-type 10 and n-type 11 previously applied anti-diffusion coating 12, which is well soldered by solders 6 and 9.

To increase the reliability of TEM, it is necessary to use solder during assembly (you can use paste or glue), the components of which do not react with thermoelectric material (p- and n-type branches) and do not serve as a source of diffusion, doping or reagent activity.

Figure 5 presents the assembly diagram of the lower heat transfer 8 TEM with semiconductor branches 10 and 11. Soldering (laying) of the semiconductor branches 10 and 11 on the contact pads of the lower heat transfer 8 can be carried out manually or mechanically (for branches with a cross section of more than 1 mm ² ). In this case, the semiconductor branches are in contact with the heat transfer hot surface or cold. The soldering temperature is selected empirically based on the melting point of the solder 9. During crystallization of the solder 9, a soldered connection 13 of the semiconductor branches 10 and 11 with the lower heat transfer 8 TEM is formed.

Figure 6 shows the assembly diagram of the IC cooling device, which is carried out in the following sequence: the semiconductor chip 1 is combined with the contact pads of the substrate 4, which is installed on the base of the housing 7 (upper heat transfer). The contact pads of the upper junction are aligned with the semiconductor branches already attached by the other side to the lower heat transfer 8. The crystal 1, substrate 4, body base 7 are fixed in relation to the semiconductor branches 10 and 11 in precision cassettes. When heated to soldering temperature, the solder 6 melts, and during crystallization, a soldered joint 14 of crystal 1 forms with substrate 4, substrate 4 with the base of the housing 7 (upper heat transfer), the upper heat transfer with semiconductor branches 10.11 of the lower heat transfer.

Thus, the assembly technology of PPI using heat sinks based on the Peltier effect is simplified.

The soldering temperature using solder 6 should be 20-25 ° C lower than the melting temperature of solder 9 of 80Bi / 20Sn (wt.%) For brazing semiconductor branches to the lower heat transfer. Otherwise, semiconductor branches from the lower heat transfer may desolder and shift relative to each other.

The connections of the contact pads of the IC crystals to each other and to the traverses of the housing are formed using the internal terminals 15 and 16. After the internal mounting of the terminals, the IP is sealed in any known manner using the cover 17.

Figure 7 presents a General view of the cooling device IC with a cooling semiconductor unit (TEM).

Metallization 5 with high electrical conductivity of the upper and lower heat transitions is connected to a single electrical circuit, which is connected to a power source 18.

To control the temperature of the housing of the IC, a thermocouple 19 is attached to it, and to stabilize the temperature (heating or cooling), the IC 20 of the thermocouple is connected to the polarity switching unit of the power supply 21.

Protection of semiconductor branches and metallization of TEM heat transfers from the external environment is carried out by pouring a special compound 22.

Based on the foregoing, it was concluded that the use of the proposed device for cooling IC provides, in comparison with existing devices, the following advantages:

1. The heat sink from the crystal to the housing increases.

2. The technology for assembling PPI using heat sinks based on the Peltier effect is simplified.

Information sources

1. Heat sink. Heat Radiating device. U.S. Pat. No. 5213153, MKI ⁵ F28D 15/02 / Itoh Satomi; Itoh Research and development Lab. CO., Ltd. - No. 853417; Claim 17.3.92; Publ. 25.5.93; Prior. 20.3.91, No. 3-130845 (Japan); NKI 165 / 104.33.

2. Shostakovsky P. Modern solutions of thermoelectric cooling for electronic, medical, industrial and household appliances // Power Electronics, 2009. No. 12. S.122, 126.

3. Islamgazina L. The use of various materials that provide optimal thermal conditions for power semiconductor devices, including modules and solid-state relays // Power Electronics, 2005. No. 3. S.97, 98.

4. IC cooling device. Integrated circuit cooling apparatus: Pat. 5457342 USA, MKI ⁶ H01L 23/02 / Herbst Gerhard G. - No. 220204; Claim 30.3.94; Publ. 10/10/95; NKI 257/712 (prototype).

Claims (1)

IC cooling device based on the use of the Peltier effect, in which an aluminum heat dissipator is glued to the IC in a ceramic case, and a cooling semiconductor block using the Peltier effect is used, characterized in that the base of the IC case is at the same time the upper heat transfer of the cooling semiconductor block, while soldering crystals to the substrate, the substrate with the base of the body (upper heat transfer TEM), the upper heat transfer with one surface of semiconductor branches of p- and n-type occurs goes at a temperature of 20-25 ° C below the soldering temperature of the other surface of the semiconductor branches to the lower heat transfer, the semiconductor branches are placed between the heat transitions in such a way that all hot surfaces are in contact with one heat transfer, and all cold surfaces are connected to the opposite and with the help of metallization in a single electrical circuit that is connected to a power source, a thermocouple is attached to it to control the temperature of the IC case, and a thermocouple is connected to stabilize the temperature (heating or cooling) ene with power source polarity switching unit.

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