JP2002241783A - Heat conduction element and hydraulic fluid containing nonfreezable additive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor chamber in which a hydraulic fluid composed of a nonfreezable additive for controlling formation of water and crystal of ice is used. SOLUTION: A heat conduction element comprises the vapor chamber which has an evaporation part and a condensation part and is closed in vacuum and a hydraulic fluid which is sealed in the vapor chamber and is composed of water and the nonfreezable additive in an effective amount to kinetically control formation of nucleus of ice and growth of crystal of ice in the hydraulic fluid when a temperature is below 0 deg.C. The heat conduction element comprises the nonfreezable additive substantially consisting of a water-soluble polymer. The heat conduction element comprises the water-soluble polymer in an amount of about 0.01 to about 1.5 wt.% based on the total of a liquid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to water-based hydraulic fluids for use in heat transfer devices. That is, the hydraulic fluid of the present invention is particularly suitable for use in a vapor chamber type heat sink in which a large temperature fluctuation occurs during transportation or storage. In this regard, the water-based hydraulic fluid may include an antifreeze additive that inhibits ice nucleation and / or ice crystal growth in a cold environment to prevent equipment damage. .

[0002]

BACKGROUND OF THE INVENTION Vapor chamber heat sinks are widely known in the heat transfer art. The vapor chamber consists of a vacuum-tight space or chamber filled with a small amount of a two-phase working fluid. Usually, water is inexpensive, has good thermal properties, and has good thermal properties and effective functions over a wide operating temperature range,
Used as hydraulic fluid. The fabrication of the vapor chamber involves placing a small amount of hydraulic fluid in a liquid state into the chamber, and then
The chamber is sealed under vacuum. As a result, a closed chamber in which water in an equilibrium state is enclosed is obtained.

[0003] In use, water in the liquid state quickly absorbs heat from the surroundings, changes phase, and causes the vapor particles to move rapidly within the chamber (eg, change to a vapor state), Transfer heat. The liquid water in the evaporator of the vapor chamber absorbs heat from a heat source located below the vapor chamber. Water heated by the heat source boils and turns into a vapor state, rises and diffuses into the condensing portion of the vapor chamber, and radiates heat to the upper surface of the vapor chamber.
When the water vapor radiates heat to the upper surface of the vapor chamber, it condenses on the upper surface of the chamber and returns to the evaporating section of the vapor chamber due to the surface tension of the wick material.

[0004] Vapor chambers have been used in the prior art for providing high temperature control performance to semiconductor microprocessor electronics.
At normal temperatures, in almost all personal computers, a conventional finned heat sink is thermally connected directly to a heat source (eg, a CPU package). The heat generated by the CPU is first absorbed by the heat sink, transmitted directly to the fins by heat conduction, and further radiated from the fins to the atmosphere by blowing cooling air to the surface of the fins. In higher temperature equipment, such as those shown above, the vapor chamber may have a CP
It is arranged between U and a heat sink and functions as a high-efficiency heat spreader.

Accordingly, the vapor chamber comes into direct contact with the CPU and absorbs heat directly from the CPU. Next, the heat is radiated to the heat sink through the vapor chamber and further radiated to the atmosphere. Since the vapor chamber is a more efficient heat transfer device, heat is transferred faster from the CPU, the temperature rise of the CPU is suppressed, and the
Better performance is obtained. Accordingly, the combined use of the vapor chamber and the heat sink can achieve higher thermal performance in heat radiation from the CPU than the heat sink alone, and can provide a more efficient solution to high-performance equipment.

[0006]

As mentioned above, vapor chambers have heretofore been used only for very high speed microprocessor applications requiring a high degree of thermal control. However, the processing speed of semiconductor microprocessors generally used in personal computers and network servers continues to increase, and in recent years, there has been an interest in applying a vapor chamber type heat sink to a wider variety of general-purpose semiconductor products. Has been shown. In order to widely apply the vapor chamber technology as described above,
Rather than special high-performance computers, there is a need for a vapor chamber suitable for the standard and various environmental conditions encountered by personal computers. Therefore, it is manufactured every day,
There is a widespread demand in the industry for a robust, highly stable vapor chamber that can withstand the environmental conditions encountered by transported and stored electronics.

Computers commonly used in standard office environments can withstand temperatures in the range between 20 and 70 degrees Celsius. Within this range, the water-based hydraulic fluid will function properly. However, when transporting and storing computers, the temperature can be as low as -4 degrees Celsius.
It may be in the range of 0 degrees to plus 70 degrees. There is no problem in the high temperature range, but the low temperature range causes a fundamental problem when using water as a working fluid in the vapor chamber.

Once the temperature falls below the freezing temperature (0 degrees Celsius), the water forms ice crystals and expands. As is well known in the art, if water expands in a closed container, at least the container is physically deformed and, at worst, ruptures the container wall. A similar situation occurs with a sealed container filled with water in equilibrium. The water in the vapor chamber may expand, causing the walls of the vapor chamber to vigorously and physically deform, and eventually damage semiconductor devices to which the vapor chamber is connected.

[0009]

SUMMARY OF THE INVENTION The present invention addresses the problem of exposing microprocessor equipment to low temperatures during transportation. The present invention solves the freezing problem by applying a working fluid consisting of water and a kinetic antifreeze additive added as a water additive to a heat conducting element such as a heat pipe type or a vapor chamber type heat sink. Is what you do. The antifreeze additive is preferably made of a water-soluble polymer that can be added in a very small amount to water so as not to affect the capillary force and thermal performance of water as a working fluid.

As described above, a preferred method of applying the working fluid is to use it in a heat conducting element such as a heat pipe type or a vapor chamber type heat sink. In this regard, one of the preferred embodiments of the present invention
One is a vapor chamber type heat sink composed of a vapor chamber having an evaporating section and a condensing section, which is sealed in a vacuum, a wick material, and a working fluid sealed in the vapor chamber. As described above, the working fluid is effective for suppressing water nucleation and crystal growth of ice in the working fluid when the working fluid is at a temperature of less than 0 degrees Celsius. It consists of a quantity of antifreeze additives.

[0011] The antifreeze additive preferably comprises a water-soluble polymer as described above. In a preferred application, the evaporator of the vapor chamber is thermally connected to the semiconductor device to remove heat from the semiconductor device. A finned heat sink structure can be mounted on top of the vapor chamber to remove heat from the vapor chamber.

Accordingly, it is an object of the present invention to provide a hydraulic fluid comprising water and an antifreeze additive which suppresses ice nucleation and crystal growth in the water; an antifreeze additive comprising a water-soluble polymer compound;
Vapor chamber (container and wick member) structured to withstand severe environmental and temperature changes encountered during transportation and storage of general consumer goods; vapor chamber filled with hydraulic fluid that suppresses the formation of ice crystals; described in the specification It is an object of the present invention to provide a vapor chamber in which a working fluid is filled. Other objects, features and advantages of the present invention will become apparent from consideration of the accompanying drawings.

A first aspect of the working fluid of the present invention is a working fluid used for a heat conducting element, comprising: water; and when the working fluid has a temperature of less than 0 degree Celsius, An antifreeze additive in an amount effective to kinetically inhibit ice nucleation and ice crystal growth in water.

A second aspect of the working fluid of the present invention is a working fluid in which the antifreeze additive is substantially composed of a water-soluble polymer.

[0015] In a third aspect of the working fluid of the present invention, from about 0.01 to about 1.5 wt. % Of the polymer in an amount in the range of%.

According to a fourth aspect of the working fluid of the present invention, the polymer has the following molecular formula, R1 is a pendant group having an amide group (NC = O) in contact with the polymer backbone, and n is Any number of hydraulic fluids greater than one.

(Equation 4)

A fifth aspect of the working fluid of the present invention is a working fluid wherein the pendant group is a lactam ring.

In a sixth aspect of the working fluid of the present invention, the polymer is a copolymer having the following molecular formula, wherein R1 is an amide group (NC = O) in contact with the polymer backbone.
Wherein R2 is a second pendant group having an amide group (NC = O) in contact with the polymer backbone, and x and y are any number greater than 1 is there.

(Equation 5)

According to a seventh aspect of the working fluid of the present invention, the polymer is a terpolymer having the following molecular formula:
Is an amide group in contact with the polymer backbone (NC =
R2 is a second pendant group having an amide group (N—C） O) in contact with the polymer backbone, and R3 is a first pendant group having an amide group (N—C ＝ O) in contact with the polymer backbone. O) is a third pendant group with x, y and z being any number greater than one.

(Equation 6)

In an eighth aspect of the working fluid of the present invention, the polymer is a working fluid selected from the group consisting of polyvinylcaprolactam (PVCAP) and polyvinylpyrrolidone (PVP) polymers, copolymers and terpolymers. .

According to a ninth aspect of the working fluid of the present invention, the polymer is polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PVCAP), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), and poly ( It is a working fluid selected from the group consisting of vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl) (VC-713).

A first aspect of the heat conduction element of the present invention is a heat conduction element comprising: a vacuum-sealed vapor chamber having an evaporator and a condenser; and water sealed in the vapor chamber. A hydraulic fluid comprising an amount of an antifreeze additive effective to kinetically inhibit ice nucleation and ice crystal growth in said hydraulic fluid at a temperature below 0 degrees Celsius.

A first aspect of the semiconductor assembly of the present invention is a semiconductor assembly comprising: a semiconductor element; a vacuum-sealed vapor having an evaporation section and a condensation section thermally connected to the semiconductor element. A vapor chamber-type heat sink having a chamber; and kinetics of water nucleation and ice crystal growth in the working fluid at a temperature of less than 0 degrees Celsius enclosed within the vapor chamber. Hydraulic fluid consisting of an effective amount of antifreeze additive to effectively control.

A first aspect of the method of the present invention is a method of preventing ice nucleation and ice crystal growth in a water-based hydraulic fluid used in a heat transfer element, said method comprising: Comprises treating the working fluid with an antifreeze additive consisting essentially of a water-soluble polymer.

A tenth aspect of the working fluid of the present invention is a working fluid used for a heat conducting element, comprising:
8.5 to about 99.9 wt. % Water; and when the working fluid is at a temperature of less than 0 degrees Celsius, effective to kinetically inhibit ice nucleation and ice crystal growth in the working fluid. About 0.1 to about 1.5 wt. % Of polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PVCAP), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), poly (vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl) (VC- 713) An antifreeze additive consisting essentially of a water-soluble polymer selected from the group consisting of:

Another aspect of the working fluid of the present invention is that the working fluid has a weight of about 0.5 to about 1.0 wt. % Of the polymer in an amount in the range of%. Another embodiment of the working fluid of the present invention is a working fluid in which the antifreeze additive is substantially composed of a water-soluble polymer. Another embodiment of the hydraulic fluid of the present invention comprises from about 0.01 to about 1.5 wt. % Of the polymer in an amount in the range of%. Another aspect of the hydraulic fluid of the present invention is that the hydraulic fluid has a weight of about 0.5
~ 1.0 wt. % Of the polymer in an amount in the range of%.

[0027] Other aspects of the heat conduction element of the present invention include:
The heat conductive element wherein the polymer has the following molecular formula, R1 is a pendant group having an amide group (NC = O) in contact with the polymer backbone, and n is any number greater than 1.

(Equation 7) Another embodiment of the heat conductive element of the present invention is a heat conductive element in which the pendant group is a lactam ring. In another embodiment of the heat conductive element of the present invention, the polymer is a copolymer having the following molecular formula, R1 is a first pendant group having an amide group (NC = O) in contact with the polymer backbone, and R2 is Is a second pendant group having an amide group (NC = O) in contact with the polymer backbone, and x and y are any number greater than one.

(Equation 8)

Another aspect of the heat conduction element of the present invention is as follows.
The polymer is a terpolymer having the following molecular formula, wherein R1 is an amide group (N-
C = O), R2 is a second pendant group having an amide group (NC = O) in contact with the polymer backbone, and R3 is an amide group (N- A third pendant group having C = O), wherein x, y and z are any number greater than one.

(Equation 9)

Another aspect of the heat conduction element of the present invention is as follows.
The polymer is polyvinylcaprolactam (PVCA)
P) and a polyvinylpyrrolidone (PVP) polymer, a copolymer, and a terpolymer. In another aspect of the heat conducting element of the present invention, the polymer is polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PVCA).
P), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), and poly (vinylpyrrolidone)
-Vinylcaprolactam-dimethylaminoethyl) (VC
-713) is a heat conductive element selected from the group consisting of:

Another embodiment of the semiconductor assembly according to the present invention is a semiconductor assembly in which the antifreeze additive substantially comprises a water-soluble polymer. Another aspect of the semiconductor assembly of the present invention is that the semiconductor assembly has a weight of about 0.01 to about 1.5 wt. A semiconductor assembly comprising an amount of the polymer in the range of%. Another aspect of the semiconductor assembly of the present invention is that the semiconductor assembly has a total weight of about 0.5 to about 1.0 wt. A semiconductor assembly comprising an amount of the polymer in the range of%.

In another embodiment of the semiconductor assembly of the present invention, the polymer has the following molecular formula, R1 is a pendant group having an amide group (NC = O) in contact with the polymer backbone, and n is 1 Any number greater than or equal to the semiconductor assembly.

(Equation 10) Another embodiment of the semiconductor assembly of the present invention is a semiconductor assembly in which the pendant group is a lactam ring.

Another embodiment of the semiconductor assembly according to the present invention is that the polymer is a copolymer having the following molecular formula, and R1 is a first pendant group having an amide group (NC = O) in contact with the polymer backbone. , R2
Is an amide group in contact with the polymer backbone (NC =
O) is a second pendant group having x and y are 1
Any number greater than or equal to the semiconductor assembly.

[Equation 11]

Another aspect of the semiconductor assembly of the present invention is that the polymer is a terpolymer having the following molecular formula, wherein R1 is a first pendant group having an amide group (NC = O) in contact with the polymer backbone. Yes, R
2 is an amide group in contact with the polymer backbone (NC =
O), a second pendant group having an amide group (NC = O) in contact with the polymer backbone, wherein x, y and z are any number greater than 1 A semiconductor assembly.

(Equation 12)

[0034] In another embodiment of the semiconductor assembly of the present invention, the polymer is polyvinylcaprolactam (PVCAP) and polyvinylpyrrolidone (PVP).
Semiconductor assembly selected from the group consisting of polymers, copolymers, and terpolymers. In another embodiment of the semiconductor assembly of the present invention, the polymer is polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PVCAP), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), and
A semiconductor assembly selected from the group consisting of poly (vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl) (VC-713).

Another embodiment of the method of the present invention is that the method comprises from about 0.01 to about 1.5 wt. % Of the polymer. Another aspect of the method of the invention is that, based on the total weight of the liquid,
About 0.5 to about 1.0 wt. % Of the polymer. Another embodiment of the method of the present invention is that the polymer has the following molecular formula: wherein R1 is a pendant group having an amide group (NC = O) in contact with the polymer backbone; Is the method that is the number of

(Equation 13)

Another embodiment of the method of the present invention is a method wherein the pendant group is a lactam ring. Another embodiment of the method of the present invention is that the polymer is a copolymer having the following molecular formula: wherein R1 is a first pendant group having an amide group (NC = O) in contact with the polymer backbone; A second pendant group having an amide group (NC = O) in contact with the backbone;
And where y is any number greater than one.

[Equation 14]

In another embodiment of the method of the present invention, wherein said polymer is a terpolymer having the following molecular formula:
Is an amide group in contact with the polymer backbone (NC =
R2 is a second pendant group having an amide group (N—C） O) in contact with the polymer backbone, and R3 is a first pendant group having an amide group (N—C ＝ O) in contact with the polymer backbone. O) is a third pendant group having X), wherein x, y and z are any numbers greater than 1.

(Equation 15)

Another embodiment of the method of the present invention is the method wherein the polymer is selected from the group consisting of polyvinylcaprolactam (PVCAP) and polyvinylpyrrolidone (PVP) polymers, copolymers and terpolymers. Another embodiment of the method of the present invention is that the polymer is polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PVCAP), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), and
This is a method selected from the group consisting of poly (vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl) (VC-713).

Another aspect of the working fluid of the present invention is that the working fluid has a weight of about 0.5 to about 1.0 wt. % Of the polymer in an amount in the range of%. Another embodiment of the heat conducting element of the present invention is a heat conducting element comprising: a vacuum-sealed vapor chamber having an evaporating part and a condensing part; and about 98.5 to about 99.
9 wt. % Water, and when the working fluid is at a temperature below 0 degrees Celsius, is effective to kinetically inhibit ice nucleation and ice crystal growth in the working fluid. About 0.1 to about 1.5 wt. % Of polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PVCAP), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), poly (vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl)
A working fluid comprising an antifreeze additive consisting essentially of a water-soluble polymer, selected from the group consisting of (VC-713).

Another aspect of the heat conduction element of the present invention is as follows.
About 0.5 to about 1.0 wt. % Of said polymer in an amount in the range of%. Another embodiment of the heat conductive element of the present invention is a heat conductive element having a finned heat sink structure thermally connected to the condensing part of the vapor chamber. Another embodiment of the heat conducting element according to the present invention is a heat conducting element containing the working fluid in an amount within a range of about 5% to about 25% by volume relative to the entire volume of the vapor chamber.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings. The heat conducting element provided with the working fluid of the present invention is shown in FIGS.
Is generally indicated by reference numeral 10. As will be described in more detail below, the heat conducting element 10 includes a hydraulic fluid 12 containing an antifreeze additive that suppresses the formation of ice nuclei and changes the ice growth pattern. Control or delay.

In the preferred embodiment of the heat conducting element 10 described herein, the heat conducting element 10 is in the special form of a heat pipe known as a vapor chamber or heat pipe lid. Generally, a heat pipe is a type of heat conducting element that conducts heat in one dimension (for example, in the longitudinal direction of the pipe). The vapor chamber is a special heat pipe with a larger flat surface. Due to the larger surface of the chamber, the heat is 2
It expands dimensionally and exhibits a high heat conduction function.

For the purposes of the present invention, the term "heat conducting element" is not limited to the preferred embodiment described, but should be interpreted broadly, not limited to heat pipes, but also to heat pipe lids, heat spreader assemblies, It is intended to include heat sink assemblies, vapor chambers, vapor chamber assemblies, and all other types of associated heat conducting elements that use or include hydraulic fluid as part of the assembly.

That is, the vapor chamber (heat conduction element 10)
Has a continuous outer wall structure 14 sealed in a vacuum, and forms an internal vapor chamber 16 in which the working fluid 12 is sealed. The baber chamber 10 has an evaporator, designated by reference numeral 18, thermally connected to at least one heat source, such as a semiconductor device, mounted on the printed circuit 22. In the illustrated embodiment, the printed circuit 22 includes a semiconductor device 20 such as a CPU. The evaporator 18 is mounted on the upper surface of the semiconductor device 20 while being thermally connected thereto. In order to strengthen the thermal connection between the upper surface of the semiconductor device 20 and the lower surface 18 of the evaporator, a thermal interface material such as a thermal grease or a heat conductive adhesive sheet indicated by reference numeral 28 is used.

The thermal interface material is conventionally known and is available from different manufacturers. The vapor chamber assembly 10 further includes an upper surface 30 that is thermally connected to a finned heat sink 32. In order to enhance the thermal connection between the upper surface of the vapor chamber 10 and the lower surface of the heat sink 32, a thermal interface material such as the above-described thermal grease or a heat conductive adhesive sheet is used. It should be noted that the heat sink 32 and the vapor chamber 10 are separate parts in the illustrated embodiment. However, this should not be construed as limiting in any way the assembly or combination of parts. Other configurations of the vapor chamber and heat sink should also be considered within the scope of the present invention.

A small amount of the working fluid 12 is sealed in the vapor chamber 16. In this regard, the amount of hydraulic fluid 12 enclosed within the vapor chamber is preferably between 5% and 25% of the total volume of the vapor chamber, more preferably between 15% and 20%. Further, code number 2
A wick member indicated by 4 is provided in the vapor chamber. The wick member 24 includes the condensed steam 26
Facilitates reflux to the evaporator 18 due to surface tension along the inner surface of the vapor chamber. Wicking members of the type contemplated here are known in the conventional heat transfer art and will not be described in further detail.

The working fluid 12 is supplied to the evaporating section 18 of the chamber 16.
In a liquid state due to surface tension as described above. In the evaporating section 18, the working fluid 12 immediately absorbs heat and boils into a vapor state. The water vapor (see the large arrow 36 in FIG. 2) rises and the condensing section 40 of the vapor chamber 16
And transfers heat to the upper surface of the chamber. Steam 36
Dissipates heat in the upper part of the lower temperature vapor chamber, the vapor condenses on the upper surface of the chamber (see small arrow 38 in FIG. 2), and with the help of the wick member 24, due to surface tension, the evaporator of the vapor chamber 16 Reflux to 18. The detailed operating characteristics of the hydraulic fluid 12, as described above, are known in the prior art and will not be described further with respect to the present invention.

The working fluid 12 is preferably made of water, and has an effective amount at a temperature lower than the freezing temperature to effectively suppress the formation of ice nuclei and the formation of ice crystals. Contains kinetic antifreeze additives.

[0049] Kinetic antifreeze additives are distinguished from thermodynamic antifreeze additives in that ice formation is suppressed. Thermodynamic antifreeze additives fall into two broad categories. That is, 1) alcohol or glycol (high vapor pressure), and 2) salt compound (low vapor pressure). These categories of antifreeze additives can be mixed with water to shift the actual freezing temperature of water very low.
In some cases, minus 40 degrees is possible with glycol addition.

However, when these compounds are used in electronic equipment, another disadvantage occurs. In the case of alcohols and glycols, very high proportions (30% to 50%) of the total amount of water are required. Due to this high rate, the vapor pressure in the vapor chamber at high temperatures is
It rises dramatically and greatly affects the thermal performance of the vapor chamber. In contrast, salt compounds become supersaturated at elevated temperatures. Further, alcohol, glycol and salt may cause a reverse reaction with copper (Cu) used in the inside of the vapor chamber and the wick member to corrode copper.

The kinetic antifreeze additive physically interacts with water molecules and ice crystals and prevents the growth of ice crystals. At temperatures less than 0 degrees Celsius, the kinetic antifreeze additive entangles or envelops the surface of the ice crystals, stopping the growth of the ice crystals and causing the small ice crystals to become larger crystals. prevent. Thus, the antifreeze additive keeps the ice crystals small and prevents them from growing to a larger stage. In other words, the kinetic antifreeze additive drastically slows or sometimes stops ice crystal growth.

The preferred kinetic antifreeze additives of the present invention are:
Water-soluble polymers, copolymers and terpolymers having at least one pendant group containing an amide group (-NC = O) at the head of each pendant ring in contact with the polymer backbone, such as a lactam ring Consists of compounds belonging to Another variation of the polymers within the scope of the present invention includes an amide group as a pendant group without a ring. These polymers are generally shown below, where R1 is a pendant group having an amide group (NC = O) in contact with the polymer backbone, and n is
Any number greater than 1.

[0053]

(Equation 16)

The types of copolymers considered in the present invention are shown below, where R1 is the first pendant group having an amide group (NC = O) in contact with the polymer backbone, and R2 is the polymer backbone. Is a second pendant group having an amide group (NC = O) in contact with x and y are any numbers greater than 1.

[0055]

[Equation 17]

Terpolymers of the type contemplated in the present invention are shown below, where R1 is the first pendant group having an amide group (NC = O) in contact with the polymer backbone, and R2 is the polymer backbone. Is a second pendant group having an amide group (NC = O) in contact with
R3 represents an amide group (N
-C = O), where x, y and z are any number greater than 1.

[0057]

(Equation 18)

The structure of the polymer taken up here is that it consists of polymers with various chain lengths, and (n), (x), (y) and (z) in the above figure are: It is well understood by those skilled in the art that it represents the average number of repeating units of a compound.

For the purpose of concretely explaining the present invention without limiting the scope of the present invention, polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PV)
CAP), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), and poly (vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl) (V
Various water soluble polymer antifreeze additives were evaluated, including C-713). These structures are shown below.

Polyvinyl caprolactam:

[Equation 19]

Polyvinyl pyrrolidone:

(Equation 20)

Polyvinyl pyrrolidone / polyvinyl caprolactam copolymer:

(Equation 21)

Polyvinylpyrrolidone / polyvinylcaprolactam / polydimethylaminoethyl terpolymer (VC-
713):

(Equation 22)

The above polymers and copolymers are commercially available from various chemical manufacturers. Therefore, their synthesis is not described here. In contrast to the prior art which required large amounts of thermodynamic antifreeze additives, kinetic antifreeze additions of the type considered in the present invention have about 0.1% by weight of water relative to water. It is desirable to add to the water an amount in the range of from about 1.5% to about 1.5%, and it has been found that an amount in the range of from about 0.5% to 1.0% by weight provides higher effects. are doing.

Experiment 1 For the purpose of specifically explaining the present invention without limiting the scope of the present invention, various polymer antifreeze additives were compared with glycol and pure water as working fluids, and evaluated and tested. Was done. A total of 60 different samples were tested and the results of the tests are shown in Table 1 (FIG. 5).

The purpose of Experiment 1 was to investigate the effect of polymer additives on the freezing of the working fluid and to verify the concept of kinetic deicing in heat pipes and vapor chambers.

[0067] Experiments using matrix polymer material 1) VC-713 2) Inhibex 501 ISP 3) Inhibex 101 ISP 4) PVCAP 5) VP / VC 6) EP-1

[0068] comparative materials 7) Ethylene glycol 8) Water

Concentration of Polymer Additives Two concentrations of hydraulic fluid were used in this experiment. The concentrations are 0.5% and 1%, which is lower than 30% and 50% of ethylene glycol (thermodynamic deicing method).

[0070] Because expensive as laboratory equipment experimental investigations, instead of using the vapor chamber, the tubes of diameter 4mm tube (wall thickness 0.5 mm) (tubes) and diameter 6 mm (thickness 0.6 mm), the present invention Used to verify the concept of. The tubes were crimped to prevent water leakage during the experiment and to prevent evaporation.

The amount used in the experiment was about five times greater than the amount used in a normal heat pipe to clearly confirm the effect of the additive on freezing.

[0072] orientation tube experiments equipment, experiments were set up in vertical orientation is the most failure prone severe direction (vertical position).

Experimental Results During the experiment, the tube diameter changed. In the experiment, two diameters were measured. See the sketch in Table 2.

Changes in Working Fluid Volume In order to examine the effects of freezing and damage to the samples, the state of leakage was frequently checked.

Experimental Method The freeze prevention experiment was performed using a special temperature cycle test equipment. The temperature cycle is from minus 40 degrees Celsius to plus 60 degrees Celsius. See sketch in Table 2. 0 cycle, 5
The cycle and the experimental result at the time of 10 cycles were measured using a micrometer and a weight balance.

Summary of Experimental Results (Experiment 1) a) After 5 cycles of VC713, the maximum weight change is 2.2% and the maximum diameter change is 2.82%. All samples did not swell.

Influence of density (1) Position of 15 mm in 4 mm diameter

(Equation 23) (2) 15mm position at 6mm diameter

(Equation 24) The results show that the higher the concentration, the less the swelling of the tube. Effect on tube diameter (1) 15mm position at 0.5% concentration

(Equation 25) (2) 15mm position at 1% concentration

(Equation 26)

Generally speaking, the larger the diameter of the tube, the greater the possibility of inflation. After 10 cycles, the maximum weight change was 10.43% (which may include weight balance errors and poorly swaged tubes) with a maximum change in diameter of 1. 3
5%. Again, no swelling occurred in any of the samples. The largest diameter change occurred in a 6 mm tube with 0.5% working fluid added.

B) Inhibex 501 After 5 cycles, only one 4 mm tube (1% strength) remained and all other samples were broken. After 10 cycles, the remaining sample broke. c) After 5 cycles of Inhibex 101, 5 out of 8 samples remained. However, the expansion of the remaining tube is very large (1.
39% to 3.72%). After 10 cycles, all samples broke.

D) PVP The result is almost the same as that of Inhibex 101. e) After 5 cycles of PVCAP, 5 samples remained. Two of them remained after 10 cycles. The remaining sample had a very good shape. f) Almost all samples were broken after 5 cycles of EP-1.

G) Ethylene glycol Both the 30% concentration and the 50% concentration liquid hardly changed. This information will be fed back into the development of new additives. h) Water After 5 cycles, two 6 mm tubes were broken. After 10 cycles
The two 4 mm tubes did not bulge, but the swelling was significant.

Conclusion VC-713 performed best in all of the tests. Furthermore, it was understood from Experiment 1 that the time required for ice crystals to grow can be extended by the kinetic deicing method. In this type of application, time is a very important matter. However, finding the right combination of polymers or other additives can prevent the growth of ice crystals that would break the tube in all applications.

Experiment 2 Based on the results of Experiment 1, samples were selected and further tested to examine the mechanism of dynamic freezing prevention, and to graph the temperature change over time. The results of Experiment 2 are shown graphically in FIGS. The test samples are as follows: 1) FTE-01-0.5 (VC-713 0.5
%) 2) FTE-01-1.0 (VC-713 1.0
%) 3) FTE-07-50 (glycol 50% concentration) 4) FTE-08 (pure water) 5) Atmospheric temperature

The working fluid is placed in an open beaker,
Expose to room temperature in the range of plus 25 degrees Celsius to minus 40 degrees Celsius (maintain for 2 hours), then
Exposure to temperatures in the range of 40 degrees to plus 40 degrees (maintained for 2 hours). The samples were subjected to only one temperature cycle. K
A thermocouple of each type was placed in each beaker and the temperature was measured. The experimental results are temperature measurement values for each time, and as a result, a graph on the temperature decreasing side shown in FIG. 3 and a graph on the temperature increasing side shown in FIG. 4 were obtained.

From the results of Experiment 2, it was found that the additive VC-713 was used.
It can be concluded that (polymer) is more effective in delaying the ice formation process than pure water. By comparing curves 1 and 2 in FIGS. 3 and 4, it can also be concluded that higher concentrations are more effective. In curve 3 (glycol), the temperature change is gentle, which means that the freezing point has moved as a whole. In FIG. 4 (temperature rise side change), curve 3
Note that the temperature change is very steep, which is not good for thermal performance. Further, it can be said in FIG. 4 that Curve 1 (VC-713) and Curve 4 (pure water) are very similar, and that the working fluid with VC-713 as an additive is similar to pure water. It has thermal performance.

Therefore, according to the present invention, it can be seen that a heat conducting device particularly suitable for use at a low temperature such as a heat pipe type or a vapor chamber type heat sink can be provided. The use of a small amount of a kinetic polymer antifreeze additive in water as a working fluid effectively suppresses ice crystal nucleation and further prevents ice crystals from growing and becoming large. The effect of the antifreeze additive added to the water is to significantly delay the time that ice crystals form.

Since the polymer antifreeze additive is added to the water in very small amounts, it is not expected to affect the thermal performance of the hydraulic fluid and the wick function (relative to surface tension). In particular, when a water-soluble lactam-based polymer is used as an antifreeze additive, a specific effect is exhibited without significantly impairing the performance and effect of the working fluid, instead of the conventional thermodynamic antifreeze additive. For the above reasons, the present invention
It has made significant progress in the art and has substantial commercial benefits.

Although the present invention is described with reference to heat conducting equipment in the field of semiconductor electronics, the hydraulic fluids described herein may be used in other industrial fields such as automobiles, air conditioners, and other applications requiring cooling. It can be applied to In this regard, the term "heat transfer device" means any type of device, including a vapor chamber, with a working fluid encapsulated therein. This term is not limited to the semiconductor applications disclosed herein and / or to heat pipes or vapor chamber type heat sinks.

Although a particular embodiment of the invention has been described, various modifications and alterations of the part may be made without departing from the spirit and concept of the invention.
It should also be apparent to one of ordinary skill in the art that the invention is not limited to the specific form described herein, except as claimed.

[0090]

According to the present invention, a hydraulic fluid comprising water, an antifreeze additive which suppresses the formation of ice nuclei in water and the growth of crystals, and a hydraulic fluid which suppresses the formation of ice crystals Can be provided.

[Brief description of the drawings]

FIG. 1 is an elevational view of a semiconductor / vapor chamber heat sink assembly with a vapor chamber heat sink structure according to the present invention.

FIG. 2 is a sectional view of a vapor chamber.

FIG. 3 is a graph of temperature change and elapsed time for various samples in a single temperature cycle (temperature drop) from plus 25 degrees Celsius to minus 40 degrees Celsius.

FIG. 4 is a graph of temperature change and elapsed time of the same sample as in FIG. 3 in a single cycle of temperature (temperature rise) from -40 degrees Celsius to +40 degrees Celsius.

FIG. 5 is a table showing the results of Experiment 1 described in the specification as Table 1 (part).

FIG. 6 is a table showing the results of Experiment 1 described in the specification as Table 1 (remaining).

FIG. 7 shows Table 2.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C10M 149/06 C10M 149/06 149/10 149/10 F28D 15/02 104 F28D 15/02 104A // C10N 20:00 C10N 20:00 Z 30:08 30:08 40:08 40:08 (71) Applicant 502021327 PERRYVILLE CORPORATE E PARK, PERRYVILLE II, CLITON, NJ 08809, UNITED STATES OF AME RICA (72) Invention Person Kazu Noda 2-8-17 Futaba, Shinagawa-ku, Tokyo (72) Inventor Jun Jun Sakagawa 1-17-17 Sakuragaoka, Hodogaya-ku, Yokohama, Kanagawa Prefecture F-term (reference) 4H104 AA01Z CE03A CE03C CE05A CE05C EA17A EA17C LA04 PA05 QA05 4J100 AG24R AQ06Q AQ08P BA11Q BA31R CA01 CA04 CA05 DA38 JA 15 JA43

Claims (13)

[Claims] 1. A hydraulic fluid for use in a heat transfer element, comprising: water; and, when the hydraulic fluid is at a temperature of less than 0 degrees Celsius, the formation of ice nuclei and the formation of ice in the water. An effective amount of antifreeze additive to kinetically inhibit crystal growth. 2. The hydraulic fluid according to claim 1, wherein said antifreeze additive consists essentially of a water-soluble polymer. 3. The method of claim 1, wherein the weight of the liquid is from about 0.01 to about 1.5 wt. 3. The hydraulic fluid of claim 2, comprising an amount of said polymer in the range of%. 4. An amide group wherein the polymer has the following molecular formula and R1 is in contact with the polymer backbone (NC = O).
3. The hydraulic fluid according to claim 2, wherein the pendant group has the formula: wherein n is any number greater than 1. 4. (Equation 1) 5. The working fluid according to claim 5, wherein said pendant group is a lactam ring. 6. The polymer of claim 1 wherein said polymer is a copolymer having the following formula: wherein R 1 is a first pendant group having an amide group (NC—O) in contact with the polymer backbone;
An amide group in which R2 is in contact with the polymer backbone (NC
The hydraulic fluid of claim 2, wherein the hydraulic fluid is a second pendant group having = 0) and x and y are any numbers greater than 1. (Equation 2) 7. The polymer according to claim 1, wherein the polymer is a terpolymer having the following molecular formula, R1 is a first pendant group having an amide group (NC = O) in contact with the polymer backbone, and R2 is in contact with the polymer backbone. Amide group (N
-C = O), wherein R3 is a third pendant group having an amide group (NC = O) in contact with the polymer backbone, wherein x, y and z are any greater than 1 3. The hydraulic fluid according to claim 2, wherein (Equation 3) 8. The polymer according to claim 1, wherein said polymer is polyvinylcaprolactam (PVCAP) and polyvinylpyrrolidone (PV
The hydraulic fluid according to claim 2, which is selected from the group consisting of polymers, copolymers and terpolymers of P). 9. The polymer according to claim 1, wherein said polymer is polyvinylpyrrolidone (PVP), polyvinylcaprolactam (PVCA).
P), poly (vinylpyrrolidone-vinylcaprolactam) (VP / VC), and poly (vinylpyrrolidone)
-Vinylcaprolactam-dimethylaminoethyl) (VC
The hydraulic fluid according to claim 2, which is selected from the group consisting of -713). 10. A heat conducting element comprising: a vacuum-sealed vapor chamber having an evaporating part and a condensing part; and said operation when water and a temperature of less than 0 degrees Celsius are enclosed in said vapor chamber. A hydraulic fluid comprising an effective amount of an antifreeze additive to kinetically inhibit ice nucleation and ice crystal growth in the liquid. 11. A semiconductor assembly comprising: a semiconductor element; a vapor chamber type heat sink having a vapor chamber sealed in a vacuum, having a vapor chamber and a condenser section thermally connected to the semiconductor element; and the vapor chamber. And an amount of antifreeze effective to kinetically inhibit ice nucleation and ice crystal growth in the working fluid at a temperature below 0 degrees Celsius with water. Hydraulic fluid consisting of additives. 12. A method for preventing ice nucleation and ice crystal growth in a water-based hydraulic fluid used in a heat conducting element, said method comprising substantially converting a water soluble polymer from a water soluble polymer. Treating the working fluid with an antifreeze additive. 13. A working fluid used for a heat conducting element, comprising: about 98.5 to about 99.9 wt. % Water; and when the hydraulic fluid is at a temperature of less than 0 degrees Celsius,
About 0.1 to about 1.5 effective to kinetically inhibit ice nucleation and ice crystal growth in the working fluid.
wt. % Of polyvinylpyrrolidone (P
VP), polyvinylcaprolactam (PVCAP), poly (vinylpyrrolidone-vinylcaprolactam) (VP
/ VC), an antifreeze additive consisting essentially of a water-soluble polymer selected from the group consisting of poly (vinylpyrrolidone-vinylcaprolactam-dimethylaminoethyl) (VC-713).