Temperature control head and relative system

Abstract

The invention refers to a temperature control head (100) which heats or cools a DUT by conduction and by means of the fluid phase change (101); the head (100) comprises a shell (110) with at least two inlet openings (111) and one outlet (112); at least a flow separator (120); a heating block (130) in contact with said flow separator (120) and / or with a heat sink (140); a heat sink (140) comprising a surface (141) with a plurality of channels (142) separated from a serpentine wall (143) which separates the channels (142); said channels (142) having a curved shape; said curved shape having maximum depth in the central area of the heat sink (140); a foil (150) with a layer of thermal interface material TIM; said TIM having a thermal conductivity greater than 50 W / (mK) at room temperature; said foil (150) compensating for non-planarity of the DUT (1).

Description

[0001] LEIBO. / 56e2025

[0002] “Temperature control head and relative system”

[0003] Description

[0004] Field of the art

[0005] The invention refers to the field of test systems for semiconductors. Still more specifically, the invention is aimed to provide a test system for semiconductors that is capable of controlling and dissipating the temperature reached by the semiconductors under test.

[0006] Prior art

[0007] The typical properties of a semiconductor are associated with electrical conduction, and in particular these include the decrease of the resistivity with the increase of the temperature, photoconduction, the photovoltaic effect and the rectification of the junctions with metals. The properties of such materials depend strongly on the doping, which can change the electrical resistivity by several orders of magnitude, given the same temperature. The different fields of use are determined by the characteristics of the semiconductor, such as the concentration of the charge carriers, their mobility, the band gap.

[0008] Presently, tests related to said semiconductors are fundamental. In addition to the electrical test of the devices with semiconductors and their artificial aging, it is essential to control the thermal performances thereof. In the sense that during the step of over-stress of the packaged device, when the device is ready for implementation, such device is tested and produces temperatures that are suitably maintained within certain ranges in order to operate said artificial aging. The stress test tends to bring the semiconductors into very prohibitive conditions with respect to the operating conditions, even coming to dissipate powers more than five times higher than those normally dissipated in operating conditions.

[0009] In order to be able to control the temperatures in said stress test steps and be able to dissipate them, it is known practice to place a cooling chamber or head above the semiconductor devices. It is also known practice to make a heat-transfer fluid flow within said cooling chamber / head which is capable of dissipating the temperature via direct heat exchange. This LEIBO. / 56e2025 allows dissipating a certain power density on the device. Nevertheless, when these semiconductor devices have powers on the order of 300 / 400 Watt or higher and the power density per square centimeter is on the order of 160 W / cm2or higher, such simple heat exchange is no longer sufficient and a non-uniform or excessive / early artificial aging is generated for all or some of the devices under test. In order to facilitate a better heat exchange, it is known to exploit the phase change of a cooling fluid.

[0010] One example of a patent that exploits such technology is the object of the patent CN112710943A by QU XUEJING et al. The invention describes a system for testing the performances of high-power semiconductor devices with phase change cooling for high-power semiconductor devices, which comprises a phase change cooling circuit, an external cooling circuit and a module for measuring the semiconductor heating temperature. The phase change cooling circuit comprises a radiator, a condenser connected to the radiator by means of a piping and a pressure stabilization device connected to the condenser and to the radiator by means of piping. The contact surface of the test block of the temperature and of the radiator is coated with a high thermal conductivity material in order to ensure that the temperature measurement thermocouple is strictly attached to the surface of the radiator and that the temperature measurement error is reduced.

[0011] Another example is the object of the patent US 10401423B2 by L. AKERS et al. The invention refers to a test system that comprises: a test slot for containing a device under test (DUT); a system for controlling the temperature comprising a phase change material, with a system for controlling the temperature in order to maintain a temperature of the phase change material in a stationary state condition, with the phase change material that changes state during a transitory condition for influencing a temperature of a thermally conductive structure and with the condition of stationary state that lasts longer than the transitory condition; and a device for moving air in order to direct the air onto the thermally conductive structure and towards the DUT in the test slot so as to influence a temperature of the DUT. The thermoconductive structure can comprise one or more metal plates and the test slit can comprise a mouth for directing the air from a motor towards the DUT. The phase change material can comprise a LEIBO. / 56e2025 hydrated salt and an organic compound. The air then passes through the mouth and above the DUT. The DUT is then heated or cooled to a desired temperature at a desired speed.

[0012] Another example is the object of the patent EP3036486A1 by Y.E. MOSHE et al. The invention describes a system and a control method for the temperature of an electronic device subjected to test. The system comprises a temperature forcing head, comprising a face positionable in thermal contact with the device, and an evaporator, in direct or indirect thermal contact with the face; and a coolant circulation subsystem, comprising a compressor, a condenser, a device for controlling the flow in order to induce a pressure drop in the coolant, and a circuit of conduits through which the coolant is flowable. The subsystem cooperates with the evaporator so as to define at least a closed circuit through which a corresponding two- phase coolant is flowable, such that, during the circulation, the coolant is maintained in a liquid phase between the compressor and the flow control device and in a gaseous phase while it flows through the evaporator. The temperature of the device is thus exchangeable by the head at a rapid speed from 50 to 150 degrees Celsius per minute. The central unit fundamentally comprises a compressor and a condenser (which is preferably coupled to an atmospheric heat exchanger). The head comprises a thermal switch, having a face configured for being placed in thermal contact with the electronic device, and an evaporator part, directly or indirectly in thermal contact with the thermal switch, and in particular with the heat spreader. Preferably the terminal part of the thermal switch which enters into thermal contact with the device under test, known as heat diffuser, is formed for having a terminal face which corresponds with the upper face of the device in terms of size and shape. Preferably the thermal switch is configured as an interchangeable component of the temperature forcing head, generally a plurality of thermal switches being present that are adapted to be part of any one head. The plurality of thermal switches can mutually differ regarding the form of the heat diffuser, such to be usable with a corresponding plurality of types of devices.

[0013] The inventions reported up to now as a merely non-limiting example are representative of the inventive-technological scenario available up to present day.

[0014] The abovementioned inventions have technical problems linked to a spraying of the parts in LEIBO. / 56e2025 contact with the devices under test (DUT - Device Under Test) such to bring to a non-uniform distribution of the temperature. Indeed, in the zones where the cooling fluid is entering, there will be lower temperatures with respect to the zones from where the cooling fluid, that has been heated, is exiting. Hence a non-uniform stress is generated of the DUT. The known systems substantially risk - rather than providing means for carrying out a reliable test - introducing additional stresses in a non-uniform manner, regarding which there is no timely control, attaining results that are not reliable or even obtaining false negatives in which parts of the DUT have been excessively stressed. In addition, the abovementioned documents, like those present in the state of the art, present the problem of not having a single interface layer with the DUT that can also be adapted to its surface thickness differences and such to have a high thermal conductivity, thus facilitating the heat exchange.

[0015] The object of the present invention is that of providing a cooling and heating head for a DUT during a stress test which is able to resolve the abovementioned problems and which is able to provide a uniform distribution and dissipation of the heat by exploiting a flow crossed with heat-transfer fluid and also allowing being able to use different fluids during a same test, also simultaneously.

[0016] The advantages offered by the present invention will be clearer in light of the following detailed descriptions.

[0017] Description of the invention

[0018] According to the present invention, a temperature control head is attained which heats or cools a device under test DUT (Device Under Test) by conduction and by means of a fluid, and the relative system in which this operates. In the context of the present invention, by DUT one intends a semiconductor device or a set of semiconductor devices. When the device is packaged, electrical stress tests are carried out. The electrical stress test is operated within specific temperature ranges. The electrical stress applied to the DUT generates an artificial aging and brings the DUT into operating conditions that are considerably more hostile (in terms of temperature and electrical stress) than the normal operating conditions. The DUT, when they are stressed, dissipate electrical power, and consequently they generate heat. The LEIBO. / 56e2025 head cools said DUT through the phase change from liquid to gaseous of the fluid. The head then exploits the latent heat of evaporation of a fluid placed in contact indirectly with the dissipative surface of the DUT itself. Said head:

[0019] - comprises a shell comprising at least two inlet openings and at least an outlet opening;

[0020] - comprises at least a flow separator which generates, when placed within the shell, at least two compartments; each compartment facing at least an inlet opening or on at least an outlet opening; said flow separator comprising holes directed towards a heating block;

[0021] - comprises said heating block in contact with said flow separator and / or with a heat sink; said heating block housing at least a cartridge heating element; said cartridge heating element heating, by conduction, said heating block which, by conduction, heats said heat sink and said DUT; said heating block comprising through holes aligned with the holes of the flow separator; the shell having an internal housing which houses said flow separator and said heating block;

[0022] - comprises said heat sink comprising a surface with a plurality of channels separated from a serpentine wall; said channels having a curved shape; said curved shape having maximum depth in the central area of the heat sink; said serpentine wall mutually separating the channels and having several rounded edges in order to convey the fluid within the channels; said surface being in contact with said shell; said serpentine wall being in contact with said heating block; said holes being aligned with the ends of the channels at said wall; the walls of the shell which delimit said housing in which flow separator and heating block are housed, ending against said surface of the heat sink;

[0023] - comprises a foil with a layer of thermal interface material TIM (Thermal Interface Material); said TIM having a thermal conductivity greater than 50 W / (mK) and preferably comprised between 50 and 80 W / (mK) at room temperature and at a pressure of 275 kPa for a material thickness comprised between 270 pm and 330 pm, a tensile strength greater than 50 kPa, a melting temperature greater than 1400°C, a percentage compressibility greater than 50%, a compressive strength greater than 100 kPa for percentage compressions comprised between 30% and 50% and for material thicknesses comprised between 270 pm LEIBO. / 56e2025 and 330 m, a specific heat comprised between 0.20 and 0.30 J / (gK), a hardness comprised between 40 and 50 measured at Shore scale; said foil with said TIM being pressed on the surface of the DUT compensating for non-planarity, when present, and attaining a continuous contact, lacking air between said heat sink and said DUT;

[0024] - said fluid entering in said head from said inlet openings is thrust into at least a compartment generated by said flow separator and is thrust into the channels of the heat sink passing through the spaces comprised between the internal surfaces of the shell and the external surfaces of the flow separator and of the heating block; said fluid changing phase from liquid to gas / vapor in said channels; said fluid in gas / vapor form being thrust through the holes of the heating block and then the holes of the flow separator into at least a compartment generated by the flow separator and being further thrust out of the head through said outlet opening; the flow of the fluid, in gas / vapor form, between the heat sink and the compartment generated by the flow separator, being accelerated with a Venturi effect generated by a section reduction between the central area of a channel and a hole.

[0025] The head in several embodiments further comprises at least a temperature gauge that measures the temperature of the DUT and / or of the foil and / or of the heat sink.

[0026] According to the present invention, a system with a head, as described, in which said inlet and outlet openings are connected to a pumping apparatus that generates a positive thrust on the fluid in the conduits connected to the inlet openings and a negative pressure in at least a conduit connected to at least an outlet opening; the system further comprising a data processing and control unit that acquires temperature data measured by said at least a temperature gauge and acquires a temperature target; said processing and control unit sends an input to said pumping apparatus in order to thrust said fluid into said head in order to dissipate the heat measured by the temperature gauge; said processing and control unit continuously receiving temperature data from said temperature gauge and sending input to said pumping apparatus in order to increase, decrease the flow rate or interrupt the flow of said fluid towards said head.

[0027] The advantages offered by the present invention are clear in light of the description set forth up to now, and will be even clearer due to the enclosed figures and to the relative detailed LEIBO. / 56e2025 description.

[0028] The invention will be described hereinbelow in at least a preferred embodiment as a nonlimiting example with the aid of the enclosed figures, in which:

[0029] Figure 1 shows a perspective view of a temperature control head 100 according to the present invention;

[0030] Figure 2 shows a partially exploded perspective view of a head 100 with a foil 150 according to the present invention;

[0031] Figure 3 shows an exploded perspective view of a head 100 according to the present invention;

[0032] Figure 4 shows a perspective sectioned according to a section plane A- A’ of a head 100 according to the present invention;

[0033] Figure 5 shows a perspective sectioned according to a section plane B-B’ of a head 100 according to the present invention;

[0034] Figure 6 shows a three-dimensional view detailed of a heat sink 140 of a head 100 according to the present invention;

[0035] Figure 7 shows an exploded perspective view of a head 100 according to the present invention;

[0036] Figure 8 shows a three-dimensional view of “streamline” type of the distribution of the speed of the flow of a fluid 101 in the head 100, obtained through the computational fluid-dynamic modeling (CFD) of the fluid-dynamic circuit of a head 100 according to the present invention.

[0037] Detailed description of the invention

[0038] The present invention will now be illustrated as a merely non-limiting, non-binding example, with reference to the figures which illustrate several embodiments relative to the present inventive concept.

[0039] With reference to FIG. 1, a perspective view of a head 100 is shown according to the present invention. In FIG. 1 as in the following description, the embodiment of the present invention LEIBO. / 56e2025 is illustrated which is deemed to be the best at present.

[0040] Figures 1-7 show a temperature control head 100 which heats or cools a device under test DUT 1 (Device Under Test) (shown in FIG. 2) by conduction and by means of a fluid 101. The head 100 cools said DUT 1 through the phase change from liquid to gaseous of the fluid 101. The head 100 then exploits the latent heat of evaporation of a fluid 101 placed in contact indirectly with the dissipative surface of the DUT 1 itself. The head 100 of the present invention comprises a shell 110 in turn comprising at least two inlet openings 111 and at least an outlet opening 112. Specifically, in FIGS. 1-8, there are two inlet openings 111 and they are placed towards the external sides of the shell 110, while there is one outlet opening 112 and it is situated in the central area of the shell 110 interposed between the two inlet openings 111.

[0041] The head 100 further comprises at least a flow separator 120 adapted to generate, when placed within the shell 110, at least two compartments 110’. Each compartment 110’ faces at least an inlet opening 111 or on least an outlet opening 112. The flow separator 120 comprises holes 120’ directed towards a heating block 130 and which entirely traverse the thickness of the flow separator 120, facing at least a compartment 110’. Specifically, in several embodiments of the present invention, as shown in FIGS. 4 and 5, the holes 120’ face a central compartment 110’ which in turn faces the outlet opening 112.

[0042] The head 100 further comprises said heating block 130 in contact with said flow separator 120 and / or with a heat sink 140. With reference to FIGS. 1-7, the heating block 130 is in contact with a heat sink 140 on the distal part with respect to the flow separator 120. Said heating block 130 houses at least a cartridge heating element 131. Said cartridge heating element 131 heats, by conduction, said heating block 130 which, by conduction, in turn heats said heat sink 140 and said DUT 1. Specifically, as will be better described hereinbelow, the heat sink 140 is in contact with a foil 150 which in turn is in contact with the DUT 1, therefore, the heat is transmitted by conduction from the cartridge heating element 131 to the DUT 1 through the heating mouth 130, the heat sink 140 and the foil 150. Said cartridge heating element 131, in several preferred embodiments of the present invention like those shown in FIGS. 3 and 4, is a 75 W and 48 V cartridge resistor 75 W and 48 V with cylindrical form, with a diameter of 6 LEIBO. / 56e2025 mm and a length of 30 mm and supplied by current by means of wired connections. Specifically, in FIGS. 3 and 4, two cartridge heating elements are employed 131 of the just- described type. Said heating block 130 comprises through holes 130’ aligned with the holes 120’ of the flow separator 120. Where with “through” holes 130’ it is intended holes that traverse the body of the heating block 130 for its entirety, from a first surface directed towards the flow separator 120 to the opposite surface directed towards the heat sink 140. Such alignment (according to a vertical direction in the figures) between the holes 120’ and 130’ is visible with specific reference to FIGS. 4, 5 and 7. The shell 110 has an internal housing suitable for housing said flow separator 120 and said heating block 130. The heating block 130 has the function of heating the DUT 1 at the moment in which the target temperature required for execution of the test is higher than a current temperature. In this manner, the head 100 is able, with the same components and without requiring disassembly / remounting operations, to dissipate from a DUT 1 as well as heat a DUT 1.

[0043] The head 100 further comprises said heat sink 140 in turn comprising a surface 141 and comprises a plurality of channels 142 separated from a serpentine wall 143. Said channels 142 have a curved shape. Said curved shape has maximum depth, always evaluated within the thickness of the heat sink 140, in the central area of the heat sink 140. It is specified that by “shape” it is intended herein the visible profile in a section (of the head 100) made with a section plane (like the planes A- A’ and B-B’ pursuant to FIGS. 4 and 5) parallel to the direction of a flow of fluid 101 within the heat sink 140, i.e. a longitudinal section of a channel 142. Such “shape” is defined “curved” since it is observed, in said longitudinal section of a channel 142 (FIGS. 4 and 5), that the bottom of the channel 142 describes a curve lacking sharp corners within the thickness of the heat sink 140 and of the wall 143. In the specific case shown in FIGS. 2-7, such curved shape starts at a point that lies on the surface 141 and ends at a point that lies on the contact surface between the wall 143 and the heating block 130. The object of such curved shape is that of preventing the formation of turbulences within the flow of the fluid 101 which otherwise would be formed with sharp corners. Therefore, the channels 142 allow, in the zone of the head 100 closest to the DUT 1 (which is indeed that of the heat sink LEIBO. / 56e2025

[0044] 140) having a flow of fluid 101 that is generally laminar and therefore easily controllable, simulatable, designable and which is free of aleatory phenomena due to the onset of turbulences in the flow. With specific reference to the FIG. 8, a three-dimensional display is observed of “streamline” type, of the distribution of the speed of the flow of a fluid 101 in the head 100, obtained through a computational fluid-dynamic modeling (CFD). On the right of FIG. 8, a graduated scale is shown, representative of speed values of the flow of the fluid 101 measured in meters per second [m / s], FIG. 8 allows observing that the flow of the fluid 101 lacks turbulences (generally laminar) in the channels 142 (at the bottom in FIG. 8). For greater description clarity, it is underlined that FIG. 8 represents the flow of the fluid 101 in a head 100 in which the fluid 101 enters through the inlet openings 111 which are at the right and left in FIG. 8 and exits from the outlet opening 112 at the center in FIG. 8.

[0045] Specifically the channels 142, in several preferred embodiments of the invention like those pursuant to FIGS. 3-8, have transverse section (evaluated on a plane perpendicular to the flow of the fluid 101 in the channel 142) of variable rectangular form where the short side of the rectangular section, which is in contact with the bottom of the channel 142, remains constant while it is the long side of said rectangular transverse section that will vary. The surface of the heating block 130 in contact with said wall 143 constitutes the “top” for said channels 142, where by “top” it is intended the internal surface of each channel 142 that is opposite the bottom. Specifically, in such preferred embodiments of the invention also shown in FIGS. 2- 8, the long side of the rectangular transverse section which is perpendicular to the bottom of the channel 142 (and perpendicular to the surface 141) varies by increasing length in the central area of the heat sink 140, before then reducing length in moving away from the central area of the heat sink 140. The curved shape, in several preferred embodiments of the invention is, therefore, an arc of circumference, or of ellipse in which the center of the circumference or the centers of the ellipse fall outside the thickness of the heat sink 140.

[0046] Said serpentine wall 143 mutually separates the channels 142 and has several rounded edges (quite visible in FIGS. 6 and 7) for conveying the fluid 101 within the channels 142, preventing the onset of turbulent flows. Said surface 141 is in contact with said shell 110. Said serpentine LEIBO. / 56e2025 wall 143 is in contact with said heating block 130. Said holes 130’ are aligned with the ends of the channels 142 at said wall 143, thus allowing the flow of the fluid 101 in vapor / gas form, exiting from the channels 142, to enter the holes 130’. The walls of the shell 110, that delimit said housing where flow separator 120 and heating block 130 are housed, terminate against said surface 141 of the heat sink 140 (as clearly visible in FIGS. 1, 2, 4 and 5).

[0047] The head 100 further comprises a foil 150 with a layer of thermal interface material TIM (Thermal Interface Material). Said TIM has a Bulk Thermal Conductivity greater than 50 W / (mK) and preferably comprised between 50 and 80 W / (mK) at room temperature and at a pressure of 275 kPa and still more preferably greater than 60 W / (mK) (reference ASTM5470), for a material thickness comprised between 270 pm and 330 pm, an elastic modulus preferably greater than 500 GPa and still more preferably greater than 1000 GPa, a tensile strength greater than 50 kPa and still more preferably greater than 100 GPa, a melting temperature greater than 1400°C and still more preferably greater than 2800°C, a percentage compressibility greater than 50%, a compressive strength greater than 100 kPa for percentage compressions comprised between 30% and 50% and for material thicknesses comprised between 270 pm and 330 pm, a specific heat comprised between 0.20 and 0.30 J / (gK), a hardness comprised between 40 and 50 measured at Shore scale. In several preferred embodiments of the present invention like that shown in FIG. 2, said TIM is graphene. The properties of the TIM are such to allow not only an optimal heat exchange but also to be able to be flexible and strong even at high temperature. Said foil 150 with said TIM is pressed on the surface of the DUT 1, compensating for non-planarity, when present, and attaining a continuous contact, lacking air between said heat sink 140 and said DUT 1 which therefore facilitates the heat exchange.

[0048] In several embodiments of the present invention, said heating block 130 is heated during a test of said DUT 1, generating a temperature difference within said channels 142. Said temperature difference is between a bottom temperature of the channel 142 (colder) and a top temperature of the channel 142 (warmer). Said bottom temperature is the lowest temperature measured at a point or at an area of the bottom of said channel 142. Said top of the channel 142, as seen, is a surface of the heating block 130, and since the latter is heated, said top temperature will be LEIBO. / 56e2025 higher. Said top temperature causes the evaporation of a part of the fluid 101, being higher than its boiling temperature. Said bottom temperature is instead below of said boiling temperature of said fluid 101. A part of said fluid 101 in contact with said top of said channel 142 thus changes phase in the passage in said channel 142. In this manner, even during tests of the DUT 1 for which said boiling temperature is not reached, said heating block 130 can be heated in order to have a greater dissipative power of the heat, still exploiting the dissipation generated by the change of the fluid 101 (even if only generated by a part of the fluid 101).

[0049] In several embodiments of the present invention, in addition, said heating block 130, said heat sink 140, said surface 141, said channels 142 and said wall 143 are comprised in a single body of a heating and dissipation block made with preferably additive technology. Said surface 141 is an edge surface of said heating and dissipation block that has “horizontal” orientation (which lies on the same plane of the surfaces 141 shown in FIGS. 2-7) such that the walls of the shell 110 which delimit said housing terminate against said surface 141.

[0050] With reference to FIG. 5, the path of a fluid 101 within the head 100 is shown. The direction of the arrows in FIG. 5 indicates the direction of the flow of fluid 101. FIG. 5 shows, for the sake of improved illustration clarity, the path of the fluid 101 only entering into one of the two inlet openings 111. Such representation is to be deemed valid only for the purpose of description / illustration clarity and not for technical clarity, since said fluid 101, in the preferred embodiments of the invention, simultaneously enters into both inlet openings 111 and exits from the single outlet opening 112. Said fluid 101 entering in said head 100 from said inlet openings 111 is thrust into at least a compartment 110’ generated by said flow separator 120 and is thrust into the channels 142 of the heat sink 140, passing through the spaces comprised between the internal surfaces of the shell 110 and the external surfaces of the flow separator 120 and of the heating block 130. Said fluid 101 changes phase from liquid to gas / vapor in said channels 142 (dotted representation of the flow of the fluid 101 in FIG. 5). Said fluid 101 in gas / vapor form is thrust through the holes 130’ of the heating block 130 and then the holes 120’ of the flow separator 120 into at least a compartment 110’ generated by the flow separator 120 and is further thrust out of the head 100 through said outlet opening 112. The flow of the LEIBO. / 56e2025 fluid 101, in gas / vapor form, between the heat sink 140 and the compartment 110’ generated by the flow separator 120, is accelerated with a Venturi effect generated by a section reduction between the central area of a channel 142 and a hole 130’. Such Venturi effect can be appreciated by means of the representation pursuant to FIG. 8 in which it is clearly observed that the flow of the fluid 101 exiting from the channels 142 and entering into the holes 120’ and 130’ (vertical sections of the flow exiting from the channels 142) is faster (see color scale of the speeds of FIG. 8 and the points taken as sample). The Venturi effect becomes essential for operating a negative pressure that carries out a “suction” of the gas / vapor from the channel towards the holes 120’, 130’ and towards the compartment 110’ that faces the outlet opening 112, in this manner the flow is automatically accelerated, allowing a quicker entrance of fluid 101 and limiting the stay time of hot gases / vapors in the zone (the channels 142 of the heat sink 140) closest to the DUT 1.

[0051] In several preferred embodiments of the present invention, the material of the shell 110 and of the flow separator 120 is natural Peek, a semicrystalline thermoplastic material having operating temperature up to 260°C and self-lubricating so as to facilitate the development of a laminar flow of fluid 101 and to limit, as much as possible, the onset of turbulent motions in the flow.

[0052] In several preferred embodiments of the present invention, said heating block 130 and said heat sink 140 are made of metal material. Still more preferably said heating block 130 and said heat sink 140 are copper cu 99.9 [UNI 5649],

[0053] In several preferred embodiments of the present invention, said fluid 101, is a fluid with low boiling point with a boiling temperature comprised between 30°C and 80°C and more preferably comprised between 55°C and 65°C. The use of a fluid with low boiling point allows exploiting, already at low temperatures, the dissipative effect of the latent heat of evaporation, considerably increasing the efficiency in the dissipation of the heat by the head 100. Said fluid 101 with low boiling point has a molecular weight preferably comprised between 180 and 270, has a freezing temperature preferably comprised between -100°C and -160°C and still more preferably comprised between -125°C and -140°C, has a liquid density preferably comprised LEIBO. / 56e2025 between 1.3 g / ml and 1.7 g / ml, has a surface tension preferably comprised between 10 dyn / cm and 18 dyn / cm, a vapor pressure preferably comprised between 100 mmHg and 500 mmHg.

[0054] In several preferred embodiments of the present invention, said fluid 101 with low boiling point is methoxy-nonafluorobutane (C4F9OCH3) which a room temperature (comprised between 15°C and 25°C) appears as a transparent liquid, colorless, odorless and which has a boiling temperature of 59°C.

[0055] In other preferred embodiments of the present invention, said fluid 101 with low boiling point is ethoxy-nonafluorobutane (C4F9OC2H5) which has a boiling temperature of 76°C.

[0056] In several preferred embodiments of the present invention like those shown in FIGS. 1-7, said shell 110, said flow separator 120, said heating block 130 and said heat sink 140 are mutually connected with bolted joints and / or with mechanical interlocks. By way of preferred example, the connections are those bolted or ensured by mechanical interlocks, they also comprise gaskets preferably made of flexible elastomeric material and resistant to temperatures preferably higher than 800°C. Specifically, in FIG. 6, circular holes are observed that are made on said wall 143, which are adapted to house threaded screws.

[0057] In several preferred embodiments of the present invention, like those shown in FIGS. 3-5 and 7, the head 100 further comprises one or more spacing plates 170 interposed between said flow separator 120 and said heating block 130 and / or between said shell 110 and said heat sink 140. Said spacing plates 170 are made of thermally insulating material. The spacing plates 170 have holes aligned with the holes 120’, 130’ when placed between said flow separator 120 and said heating block 130 as clearly visible from FIGS. 3-5 and 7. Where by “thermally insulating material” it is intended a material preferably having a thermal conductivity lower than 2 W / (mK). By way of preferred example such spacing plates 170 are made of silicone rubber VMQ (Vinyl Methyl Silicone). The spacing plates have the function of limiting the propagation of the heat by contact between shell 110 and heat sink 140 and / or between flow separator 120 and heating block 130. In this manner the materials constituting shell 110 and flow separator 120 can have operational temperatures that are even lower than those reached by the DUT 1 during a test. LEIBO. / 56e2025

[0058] In several preferred embodiments of the present invention, like those shown in FIGS. 3-5 and 7, the head 100 further comprises at least a temperature gauge 160 suitable for measuring the temperature of the DUT 1 and / or of the foil 150 and / or of the heat sink 140. Said temperature gauge 160 is, in several preferred embodiments of the invention like those pursuant to FIGS. 3-5 and 7, a temperature probe. Said temperature gauge 160 is preferably placed in contact with the foil 150. The temperature gauge 160 communicates the temperature measured at a data processing unit outside the head 100.

[0059] The preferred embodiment of the present invention is that pursuant to FIGS. 1-8, in which the head 100 comprises two inlet openings 111, an outlet opening 112, in which said flow separator 120 generates two compartments 110’ which each face an inlet opening 111 and a compartment 110’ which faces the outlet opening 112, in which said heating block 130 houses two cartridge heating elements 131, in which said head 100 comprises two temperature gauges 160.

[0060] The present invention also relates a system which comprises the head 100 and in which said inlet openings 111 and outlet opening 112 are connected to a pumping apparatus adapted to generate a positive thrust on the fluid 101 in the conduits connected to the inlet openings 111 and a negative pressure in at least a conduit connected to at least an outlet opening 112. The system further comprises a data processing and control unit (CPU) that acquires temperature data measured by said at least a temperature gauge 160 and acquires a temperature target provided to the CPU by a user by means of an interface. Said processing and control unit sends an input to said pumping apparatus in order to thrust said fluid 101 into said head 100 in order to dissipate the heat measured by the temperature gauge 160. Said processing and control unit continually receiving temperature data from said temperature gauge 160 and sending input to said pumping apparatus in order to increase, decrease the flow rate or interrupt the flow of said fluid 101 towards said head 100. The fluid 101 is introduced within the head 100 at a temperature preferably equal to the room temperature (generically between 15°C and 25°C) or in any case at a monitored temperature lower than its boiling temperature. The metering of the fluid 101 is operated by the pumping apparatus and by the CPU. The CPU in preferred LEIBO. / 56e2025 embodiments of the present invention opens bypasses / valves by varying the flow rate of the fluid 101 in order to ensure a precise flow rate of the fluid 101 as a function of the electrical power dissipated by the DUT 1 during a test, of the temperature detected by the temperature gauge 160 and of an objective temperature (or set point temperature) for the DUT 1 itself. At the moment in which, during specific test activities, the power of the DUT 1 increases (thus generating heat), the system increases the spraying operation of the pump (increases the flow rate of the flow of fluid 101 conveyed by the pumping apparatus towards the head 100). For such purpose, in several preferred embodiments of the present invention, the system advantageously comprises power meters of the DUT 1, so as to have not only a temperature control but also a power control and so as to trigger the spraying of the head 100 even before this reaches a threshold temperature, being based on the dissipated electrical power data.

[0061] In several embodiments of the present invention, the system comprises tanks with at least two different fluids 101. Said tanks are connected to the pumping apparatus. Said fluids 101 have different boiling temperatures. Said processing and control unit knows said boiling temperatures of the fluids 101 that are provided by a user by means of an interface which allows communicating with the CPU and defining various parameters for example through an input by means of keyboard. Said processing and control unit sends input to said pumping apparatus in order to start and / or interrupt the flow of a fluid 101 towards said head 100. In this manner, the CPU can evaluate that the temperature of the DUT 1 during a certain test phase is such to require a dissipation of heat operated by a first fluid 101. During the same test, the CPU, by reading the temperature data of the temperature gauges 160, can evaluate that the temperature is such (e.g. an overly high temperature) to require a dissipation of heat operated by a second fluid 101 (e.g. as a non-limiting example, with a boiling temperature higher than that of the first fluid 101). In this case, the CPU can send input to the pumping apparatus in order to interrupt the supply of the first fluid 101 towards the head 100 and instantaneously start the supply of the second fluid 101 towards the head 100. In this manner, it is also possible to introduce conservative logics and temperature limits. For example, by means of said interface, a user can define a temperature limit of DUT 1 (or also of foil 150 or LEIBO. / 56e2025 also of heat sink 140 or of any other element regarding which the temperature gauge 160 provides data), beyond which the CPU must send said input to the pumping apparatus in order to interrupt preceding flows of a fluid 101 and start the flow of another fluid 101. Additionally the user can provide temperature ranges of DUT 1 for which the CPU must send input to supply the head 100 with a specific fluid 101. In addition, in several embodiments of the present invention, in the two inlet openings 111 of the head, two different fluids 101 can be thrust.

[0062] Finally, it is clear that the modifications, additions or variations that are obvious for a man skilled in the art can be applied to invention described up to now, without departing from the protective scope that is provided by the enclosed claims.

Claims

LEIBO. / 56e2025Claims1. Temperature control head (100) which heats or cools a device under test DUT (1) by conduction and via a fluid (101); said head (100) cooling said DUT (1) through the phase change from liquid to gaseous of the fluid (101); said head (100) being characterized in that:- it comprises a shell (110) comprising at least two inlet openings (111) and at least one outlet opening (112);- it comprises at least one flow separator (120) which generates, when placed inside the shell (110), at least two compartments (110’); each compartment (110’) facing at least one inlet opening (111) or at least one outlet opening (112); said flow separator (120) comprising holes (120’) facing a heating block (130);- it comprises said heating block (130) in contact with said flow separator (120) and / or with a heat sink (140); said heating block (130) housing at least one cartridge heating element (131); said cartridge heating element (131) heating, by conduction, said heating block (130) which, by conduction, heats said heat sink (140) and said DUT (1); said heating block (130) comprising through holes (130’) aligned with the holes (120’) of the flow separator (120); the shell (110) having an internal housing suitable for housing said flow separator (120) and said heating block (130);- it comprises said heat sink (140) comprising a surface (141) and a plurality of channels (142) separated by a serpentine wall (143); said channels (142) having a curved shape; said curved shape having maximum depth in the central area of the heat sink (140); said serpentine wall (143) mutually separating the channels (142) and having some rounded edges to convey the fluid (101) into the channels (142); said surface (141) being in contact with said shell (110); said serpentine wall (143) being in contact with said heating block (130); said holes (130’) being aligned with the ends of the channels (142) at said wall (143); the walls of the shell (110) delimiting said housing in which the flow separator (120) and heating block (130) are housed, ending against said surface (141) of the heat sink (140);LEIBO. / 56e2025- it comprises a foil (150) with a layer of TIM thermal interface material; said TIM having a thermal conductivity greater than 50 W / (mK) at room temperature and at a pressure of 275 kPa, a tensile strength greater than 50 kPa, a melting temperature greater than 1400°C, a percentage compressibility greater than 50%, a compressive strength greater than 100 kPa for percentage compressions between 30% and 50% and for material thicknesses between 270 pm and 330 pm, a specific heat between 0.20 and 0.30 J / (gK), a hardness between 40 and 50 measured in Shore scale; said foil (150) with said TIM being pressed onto the surface of the DUT (1) compensating for non-planarity, when present, and creating a continuous and air-free contact between said heat sink (140) and said DUT (1);- said fluid (101) entering said head (100) from said inlet openings (111) is thrust into at least one compartment (110’) generated by said flow separator (120) and is thrust into the channels (142) of the heat sink (140) passing through the spaces between the internal surfaces of the shell (110) and the external surfaces of the flow separator (120) and the heating block (130); said fluid (101) changing phase from liquid to gas / vapor in said channels (142); said fluid (101) in gas / vapor form being thrust through the holes (130’) of the heating block (130) and then the holes (120’) of the flow separator (120) into at least one compartment (HO’) generated by the flow separator (120) and being further thrust out of the head (100) through said outlet opening (112); the flow of the fluid (101), in the form of gas / vapor, between the heat sink (140) and the compartment (110’) generated by the flow separator (120), being accelerated with a Venturi effect generated by a reduction in section between the central area of a channel (142) and a hole (130’).

2. Head (100), according to preceding claim 1, characterized in that said fluid (101), is a low boiling fluid with a boiling temperature between 30°C and 80°C.

3. Head (100), according to preceding claim 1 or 2, characterized in that said heating block (130) is heated during a test of said DUT (1) generating a temperature difference within said channels (142); said temperature difference being between a bottom temperature ofLEIBO. / 56e2025 the channel (142) and a top temperature of the channel (142); said bottom temperature being the lowest temperature measured at a point on the bottom of said channel (142); said top temperature being higher than the bottom temperature, said top being part of said heating block (130); said top temperature causing evaporation of the fluid (101) being higher than its boiling temperature; said bottom temperature being below said boiling temperature of said fluid (101); a portion of said fluid (101) in contact with said top of said channel (142) changing phase in the passage in said channel (142).

4. Head (100), according to any of the preceding claims, characterized in that said shell (110), said flow separator (120), said heating block (130) and said heat sink (140) are mutually connected with bolted joints and / or with mechanical interlocks.

5. Head (100), according to any of the preceding claims, characterized in that said heating block (130), said heat sink (140), said surface (141), said channels (142) and said wall (143) are included in a single body of a heating and dissipation block made with additive technology; said surface (141) being an edge surface of said heating and dissipation block.

6. Head (100), according to any of the preceding claims, characterized in that it further comprises one or more spacer plates (170) interposed between said flow separator (120) and said heating block (130) and / or between said shell (110) and said heat sink (140); said spacer plates (170) being made of thermally insulating material; said spacer plates (170) having holes aligned with the holes (120’, 130’) when placed between said flow separator (120) and said heating block (130).

7. Head (100), according to any of the preceding claims, characterized in that it further comprises at least one temperature gauge (160) suitable for measuring the temperature of the DUT (1) and / or the foil (150) and / or the heat sink (140).

8. Head (100), according to the preceding claim 7, characterized in that it comprises two inlet openings (111), one outlet opening (112); said flow separator (120) generating two compartments (HO’) each facing an inlet opening (111); said flow separator (120) generating a compartment (110’) facing the outlet opening (112); said heating block (130) housing two cartridge heating elements (131); said head (100) comprising twoLEIBO. / 56e2025 temperature gauges (160).

9. System comprising a head (100), according to any of the preceding claims 7 or 8, wherein said inlet (111) and outlet openings (112) are connected to a pumping apparatus adapted to generate a positive thrust on the fluid (101) in the conduits connected to the inlet (111) openings and a negative pressure in at least one conduit connected to at least one outlet (112); the system further comprising a data processing and control unit acquiring temperature data measured by said at least one temperature gauge (160) and acquiring a target temperature; said processing and control unit sending an input to said pumping apparatus to thrust said fluid (101) into said head (100) to dissipate the heat measured by the temperature gauge (160); said processing and control unit continuously receiving temperature data from said temperature gauge (160) and sending input to said pumping apparatus to increase, decrease the flow rate or interrupt the flow of said fluid (101) towards said head (100).

10. System, according to the preceding claim 9, characterized in that it comprises tanks with at least two different fluids (101); said tanks being connected to the pumping apparatus; said fluids (101) having different boiling temperatures; said processing and control unit knowing said boiling temperatures; said processing and control unit sending input to said pumping apparatus to start and / or interrupt the flow of a fluid (101) towards said head (100).

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