US20170016131A1

US20170016131A1 - Growth method of dendritic crystal structure that provides directional heat transfer

Info

Publication number: US20170016131A1
Application number: US14/800,243
Authority: US
Inventors: Jenn-Shing Wang; Yu-ching Wang; Jia-Yu WU
Original assignee: Far East University
Current assignee: Far East University
Priority date: 2015-07-15
Filing date: 2015-07-15
Publication date: 2017-01-19

Abstract

A growth method of dendritic crystal structure that provides directional heat transfer, including the steps: A. providing a substrate, whereby the substrate is provided with a plurality of crystal defects; B. depositing a plurality of metal ions on the substrate using a deposition method, whereby the metal ions on the crystal defects enable the growth of dendritic crystals. Moreover, an interspace is provided between each of the dendritic crystals. Hence, when the substrate is in contact with a heat source, heat energy is transferred from the substrate in the growth direction of the dendritic crystals; or, when the dendritic crystals are disposed at the position of a heat source, heat provided by the heat source is transferred from the dendritic crystals in a direction toward the substrate. Accordingly, the fractal structure of the dendritic crystals is used to provide ample heat dissipation areas and contact areas.

Description

BACKGROUND OF THE INVENTION

(a) Field of the Invention
The present invention relates to a growth method of dendritic crystal structure that provides directional heat transfer, and more particularly to a method that uses a current concentration effect to achieve the growth of dendritic crystals that provide directional heat transfer. Moreover, the dendritic crystals that are formed differ from whiskers grown by extrusion using the internal stress of ductile metal.
(b) Description of the Prior Art
Due to the current development trend for light weight and greater slimness in electronic devices, thus, how to enable heat transfer components, under the condition of smaller dimensions, achieve more rapid effective cooling of the heat produced by electronic devices is a persistent technical problem waiting to be resolved by relevant manufacturers.
The majority of current common heat transfer components use copper or an aluminum substrate that have a good heat conduction effect, and a plurality of heat dissipating fins are disposed on the copper or the aluminum substrate. Moreover, heat dissipating fins are used to transmit outward the heat produced by electronic devices and cool down the devices. However, the heat dissipation areas provided by the heat dissipating fins and the copper or aluminum substrate themselves are limited, thus it is difficult to further improve the heat dissipation efficiency of the electronic devices.
Other manufacturers have developed a method whereby they use whisker structures originally regarded as defects during the process of electroplating to serve as heat transfer components, which are primarily used in heat pipe elements. Related inventions of the prior art include Europe patent No. EP0999590 titled “Heat sink for electric and/or electronic devices,” U.S. Pat. No. 3,842,474 titled “Heat transfer between solids and fluids utilizing polycrystalline metal whiskers,” and Taiwan patent No. 201326718 titled “Heat dissipating structure for heat dissipating device.”
However, the aforementioned whiskers grow via release of residual internal stress in the plating, and the speed of growth using such a mechanism is not only considerably slow but also requires a comparatively longer preparation time. Furthermore, the majority of whiskers assume rod shapes with comparatively thin diameters, and are of single crystal type, which are unable to provide a greater interfacial area. Hence, the heat dissipation areas that such a method are able to provide is similarly limited, and the heat dissipation effect is inferior.
Furthermore, another defect commonly seen in current electroplating is dendritic crystals, and the reason why dendritic crystals are produced is because during the process of electroplating, metal ions concentrate on protruding areas due to the electric current, and such an effect influences deposit concentration on the protruding areas of the substrate, on which grow dendritic crystals. Because such dendritic crystals seriously affect the smoothness and aesthetics of the plated elements, thus, they have always been regarded as defects that must be avoided.
For example, in 2008, Mr. Tsai Yi-da wrote a master's thesis titled “Effect of a complexing agent in electrotinning-bismuth lead-free solder material composition control, adhesivity, and dendritic structure growth” for his master's degree at National Chung Cheng University, and in the abstract he mentions: “ . . . previous studies have pointed out that problems exist in Sn—Bi plating obtained using electroplating methods including inferior adhesivity and dendritic structure growth. Hence, in order to effectively control the production of dendritic structures, it is necessary to add a complexing agent or add an interfacial agent to control such . . . .” Accordingly, current dendritic crystals in the field of electroplating are still regarded as defects, and have no special function.

SUMMARY OF THE INVENTION

Accordingly, in order to improve the shortcomings of the limited heat dissipation areas of heat dissipation elements of the prior art, the author of the present invention devoted himself to research to provide a growth method of dendritic crystal structure that provides directional heat transfer, and which comprises the following steps:
A. Providing a substrate, whereby the substrate is provided with a plurality of crystal defects separated at intervals;
B. Depositing a plurality of metal ions on the substrate using a deposition method, whereby the aforementioned metal ions deposited on the crystal defects enable the growth of dendritic crystals, and an interspace is formed between each of the dendritic crystals.
Furthermore, in step A, a coated whisker layer is plated on the substrate, and the material of the coated whisker layer is any one or a combination of the following: tin, cadmium, zinc, antimony, or indium. The plurality of whiskers formed on the substrate serve as the aforementioned crystal defects.
Moreover, in step A, processing is carried out on the substrate to form the aforementioned crystal defects on the substrate.
Wherein the processing is a cutting process.
Furthermore, in step B, the substrate serves as an electrode for electroplating, wherein the electroplating current density for is 1 A/dm²˜5 A/dm², and the electroplating time is 60 min˜180 min.
Furthermore, the length of the aforementioned dendritic crystals is 0.1 mm˜15 mm.
Furthermore, the length of the aforementioned dendritic crystals is 1 mm˜5 mm.
Furthermore, the interspace between each of the aforementioned dendritic crystals is at least 0.1 mm˜0.5 mm.
Furthermore, in step A, a cover member with poor electrical conductivity is disposed at a predetermined position on the substrate, and the cover member prevents the growth of dendritic crystals at the predetermined position.
Furthermore, the density of the aforementioned dendritic crystals on the substrate is 3/cm²˜15/cm².
Furthermore, the substrate is a conductive metal, and in step B, the substrate first undergoes a pre-processing for cleaning. The pre-processing comprises a degreasing procedure used to remove grease and a sensitization procedure, in which the sensitization procedure comprises soaking the substrate in an acidic solution, which increases the adhesion effect of the aforementioned metal ions when carrying out electroplating.
The procedure further comprises a step C, wherein the substrate and the dendritic crystals are coated with an anti-oxidation layer.
Furthermore, the substrate serves as an electrode for electroplating, and in step B, the temperature condition for deposition is 30° C.˜60° C., the deposition time is 2 hours, and the current density is 28 A/dm²˜8 A/dm². Moreover, the pH value of the copper plating solution used to soak the aforementioned substrate is 0˜2.5.
Furthermore, in step B, the substrate serves as an electrode for electroplating, and the temperature condition for electroplating is 30° C.˜60° C., the electroplating time is 2 hours, and the current density is 2.8 A/dm²˜8 A/dm². Moreover, the pH value of the copper plating solution used to soak the aforementioned substrate is 1.45, and the specific gravity is 1.190.
The effectiveness of the present invention lies in:
1. In traditional electroplating technology, dendritic crystals have always been regarded as defects, however, the present invention overcomes the prejudice of this technology and uses the dendritic crystals for application in heat transfer components to provide directional heat transfer. Moreover, the present invention uses the dendritic crystals to provide more heat dissipation areas to further improve heat dissipation efficiency.
2. The present invention uses whiskers or processing to provide crystal defects required for the growth of dendritic crystals, thereby enabling superior growth effectiveness of the dendritic crystals. Moreover, the present invention enables control of the position of dendritic crystal growth on the substrate, and thus has superior practical value.
3. The present invention uses whiskers to serve as crystal defects to enable the dendritic crystals to compactly and firmly join to the substrate, thereby further increasing the heat dissipation efficiency of the dendritic crystals.
4. Regarding the plurality of dendritic crystals of the present invention, an interspace is provided between each of the dendritic crystals to serve as heat exchange interspaces to prevent a thermal deposition phenomena from occurring ensure the heat dissipation effect of the dendritic crystals.
5. Regarding the plurality of dendritic crystals of the present invention, when the length of each dendritic crystal is 1 mm˜5 mm, and the interspace between each of the dendritic crystals is at least 0.1 mm˜5 mm, then the heat dissipation effect is optimum.
To enable a further understanding of said objectives and the technological methods of the invention herein, a brief description of the drawings is provided below followed by a detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the steps involved to produce dendritic crystals in an embodiment of the present invention.

FIG. 2 is a schematic flow chart of the steps involved to produce dendritic crystals in the embodiment of the present invention.

FIG. 3A is an external view 1 of dendritic crystals viewed using a scanning electron microscope at different magnifications of the embodiment of the present invention.

FIG. 3B is an external view 2 of dendritic crystals viewed using a scanning electron microscope at different magnifications of an embodiment of the present invention.

FIG. 3C is an external view 3 of dendritic crystals viewed using a scanning electron microscope at different magnifications of the embodiment of the present invention.

FIG. 3D is an external view 4 of dendritic crystals viewed using a scanning electron microscope at different magnifications of the embodiment of the present invention.

FIG. 3E is a microscope external view of dendritic crystals viewed using an optical microscope at 450 magnification of another embodiment of the present invention.

FIG. 3F is a microscope external view 2 of dendritic crystals viewed using an optical microscope at 450 magnification of the other embodiment of the present invention.

FIG. 3G is a microscope external view 3 of dendritic crystals viewed using an optical microscope at 450 magnification of the other embodiment of the present invention.

FIG. 4A is a computer generated image of an external view 1 of whiskers in the embodiment of the present invention.

FIG. 4B is an external view 2 of the whiskers in the embodiment of the present invention using an electron microscope.

FIG. 4C is an external view 3 of the whiskers in the embodiment of the present invention using an electron microscope.

FIG. 4D is an external view 4 of the whiskers in the embodiment of the present invention using an electron microscope.

FIG. 5 is a planar schematic view of burrs produced in substrate drill holes in the embodiment of the present invention.

FIG. 6 is a planar schematic view depicting use of the substrate edge to grow dendritic crystals according to the embodiment of the present invention.

FIG. 7 is a side schematic view of the embodiment of the present invention based on an actual sampling.

FIG. 8 is a schematic view of a thermal image of the embodiment of the present invention depicted in FIG. 7.

FIG. 9 is a comparison chart comparing a variety of test specimens with the embodiment of the present invention under sustained contact with the same heat source (LED (light-emitting diode) for 30 minutes.

FIG. 10 is a schematic view of a thermal image of the hot air situation on the surface of the dendritic crystals of the embodiment of the present invention.

FIG. 11 is a schematic view of a temperature curve of the surface of the dendritic crystals of the embodiment of the present invention.

FIG. 12 is a schematic view of a thermal image of the heat transfer situation on the surface of 3 mm single dendritic crystals of the embodiment of the present invention.

FIG. 13 is a schematic view of a temperature curve of the heat transfer situation of 3 mm single dendritic crystals of the embodiment of the present invention.

FIG. 14 is a schematic view of a thermal image of the heat transfer situation of 0.75 mm single dendritic crystals of the embodiment of the present invention.

FIG. 15 is a schematic view of a temperature curve of the heat transfer situation of 0.75 mm single dendritic crystals of the embodiment of the present invention.

FIG. 16 is a schematic view of a thermal image of the hot air situation between two dendritic crystals of the embodiment of the present invention.

FIG. 17 is a schematic view of a temperature curve of the heat transfer situation between two dendritic crystals of the embodiment of the present invention.

FIG. 18 is a schematic view 1 of radial dendritic crystals formed using different deposition parameters according to the present invention.

FIG. 19 is a schematic view 2 of radial dendritic crystals formed using different deposition parameters according to the present invention.

FIG. 20 is a schematic view 1 of columnar type dendritic crystals formed using different deposition parameters according to the present invention.

FIG. 21 is a schematic view 2 of columnar type dendritic crystals formed using different deposition parameters according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The above and other detailed contents, features and effects with respect to the growth method of dendritic crystal structure that provides directional heat transfer of the present invention will be clearly presented in the following preferred embodiments and accompanying drawings.
Referring first to FIG. 1 and FIG. 2, which show a step flow diagram and a preparation flow diagram, respectively, of an embodiment of a growth method of dendritic crystal structure that provides directional heat transfer of the present invention, comprising the following steps: A. Providing a substrate (1), whereby a substrate (1) is provided with a plurality of crystal defects (11) separated at intervals. The definition of the crystal defects (11) in the present invention is hereby described as not only including forms whereby there is damage to the regular crystal structure such as general point defects and line defects, but also includes whisker type defects. It is preferred that the substrate (1) is made from metal that has electric conductivity and high heat conductibility, such as copper or aluminum. Moreover, pre-processing is carried out on the substrate (1), wherein the pre-processing comprises a degreasing procedure used to remove grease and a sensitization procedure. The sensitization procedure comprises soaking the substrate (1) in an acidic solution to increase the adhesion effect of the metal ions from the aforementioned metal when carrying out electroplating.
However, it is hereby specially stated that the substrate (1) is not limited to conductive materials but can also be made from non-conductive materials such as plastic or ceramic. For example, when the substrate (1) is made from plastic or ceramic, then the substrate (1) must first undergo chemical etching and surface activation procedures, which are procedures described in the prior art, and thus not further detailed herein.
It is preferred that a cover member having poor electrical conductivity is first disposed at a predetermined position on the substrate (1), thereby preventing growth of dendritic crystals (13) at the predetermined position. For example, a stainless steel piece is disposed on the periphery of the substrate (1).
B. Depositing a plurality of metal ions on the substrate (1) using deposition method to form a metal layer (12). Because of a current concentration effect, thus, the aforementioned metal ions enable the dendritic crystals (13) to grow on the aforementioned crystal defects (11). However, it is hereby specially stated that the aforementioned metal layer (12) does not have to completely cover the substrate (1), and the current concentration effect principle can be used to independently grow the dendritic crystals (13). Furthermore, the deposition method includes practical methods such as electroplating, physical vapor disposition (PVD), chemical vapor disposition (CVD), and the like. In the present embodiment, the substrate (1) is used to serve as an electrode for electroplating, and an electroplating method is used to serve as an example.
Each of the dendritic crystals (13) comprises a main branch (131) and at least one side branch (132) connected to the main branch (131). It is preferred that the length of the dendritic crystals (13) is 0.1 mm˜15 mm, and the optimal preference is that the length of the dendritic crystals (13) is 1 mm˜5 mm. Moreover, there is an interspace (D) between each of the dendritic crystals (13), and the optimal length of the interspace (D) is 0.1 mm˜5 mm, wherein the specific value of the diagonal length of the height and cross-section of the dendritic crystal (13) is greater than 2 so as to provide adequate space to serve as a heat exchange interspace and prevent a thermal deposition phenomena from occurring. In more detail, current density for the electroplating is 1 A/dm²˜5 A/dm², and electroplating time is 60 min˜180 min. Referring to FIGS. 3A to 3D, which show external views of dendritic crystals (13A), (13B), (13C) and a side branch (132D) using a scanning electron microscope (SEM) at different magnifications, wherein the dendritic crystals (13A), (13B), (13C) comprise main branches (131A), (131B), (131C), respectively, and at least side branches (132A), (132B), (132C) connected to the main branches (131A), (131B), (131C), respectively.
Referring to FIGS. 3E to 3G, which show external views of dendritic crystals (13D), (13E), (13F), respectively, using a electron microscope at 450 magnification, wherein the electroplating conditions are: electroplating temperature: 30° C.˜60° C., electroplating time: 2 hours, current flow: 2.8 A/dm²˜8 A/dm², and a plating solution is copper plating solution with a pH value of 0˜2.5. Wherein the. optimal preferences for the copper plating solution are: pH: 1.45, specific weight: 1.190, which enable forming the dendritic copper crystals (13D), (13E), (13F) having superior strength and superior heat dissipation effect. In addition, referring to FIGS. 18 to 21, which show dendritic crystals (13G), (13H), (13I), (13J) formed using different parameters, and the entire forms of the dendritic crystals (13G), (13H), (13I), (13J) includes radial shapes (FIG. 18 and FIG. 19) and columnar shapes (FIG. 20 and FIG. 21). It is hereby specifically pointed out that the dendritic crystals are not limited to forms having a main branch and side branches, but forms having columnar shape are also feasible for the dendritic crystals.
Referring to FIG. 4A, and in combination with the diagrams depicted in FIG. 2, it is preferred that in step A the substrate (1) is further plated with a whisker layer (100), the material of the coated whisker layer (100) is any one or a combination of the metals: tin, cadmium, zinc, antimony, or indium. Because these metal materials have relatively low hardness and good malleability, thus, when the metal material releases internal stress, whiskers are able to relatively easily grow on the substrate (1), and the whiskers are used to serve as the aforementioned crystal defects (11), thereby providing the dendritic crystals (13) with a definite bonding strength. Referring to FIGS. 4B to 4D, which show different types of whiskers using a scanning electron microscope (SEM) at 50 magnification, and although there are a variety of variant types, however, all are formed using the internal stress released from metals that have good ductility.
However, it is important to note that the present invention is not limited by such. Referring to FIG. 5, machine processing (including cutting processes such as drilling, milling, turning, hole forging, planing, and the like) can also be carried out on a substrate (1 a) to form burrs that serve as crystal defects (11 a). Referring to FIG. 6, it is even possible to directly use one edge of a substrate (1 b) to serve as a crystal defect (11 b). The primary objective in all cases is to use the crystal defects to cause the current flow in that area to produce a current concentration effect.
Referring again to the view depicted in FIG. 2, which further comprises a step C, wherein the substrate (1) and the dendritic crystals (13) are coated with an anti-oxidation layer (14) to prevent oxidation of the substrate (1) and the dendritic crystals (13).
Referring again to the view depicted in FIG. 2, the purpose and method of application of the dendritic crystal structure that provides directional heat transfer in the embodiment of the present invention comprise the following steps:
A. Providing the aforementioned dendritic crystal structure that provides directional heat transfer.
B. Then, causing the substrate (1) of the aforementioned dendritic crystal structure that provides directional heat transfer to come into contact with a heat source, and transferring the heat produced by the heat source from the substrate (1) in the direction of the main branch (131) and the side branches (132) of the aforementioned dendritic crystal (13).
The following first provides a description of the circumstances of tests carried out using the dendritic crystal structure that provides directional heat transfer of the present invention in actual use.
Referring to FIG. 7 and FIG. 8, which are respectively side views depicting a test sample (S) and the heat transfer effectiveness of dendritic crystals on the test sample (S) using thermal images. Moreover, three areas in FIG. 8 were chosen to analyze the temperature variations therein. From the view of area P1 it can be seen that the dendritic crystals easily cause temperature accumulation when excessively close-packed. The extremities of the dendritic crystals of area P2 are at a temperature of 47.08° C., and this temperature is relatively higher than the temperature at the extremities of other tree-like crystals. Because area P1 is close to the heat source, thus, the accumulation of heat causes the temperature at the periphery of area P1 to be on the high side. Area P3 is a single dendritic crystal, and the temperature at the extremity of this single dendritic crystal has fallen to 43.01° C. Accordingly, a preliminary inference is that the dendritic crystals contribute to heat dissipation.
Referring to FIG. 9, which shows a temperature comparison chart comparing various test pieces with the dendritic crystal structure of the present invention in sustained contact with the same heat source (LED lamp) for 30 minutes, wherein the test pieces included a pure aluminum plate, a micro-perforated plate, and copper coated micro-perforated plates. In order to compare with the dendritic crystal structure of the present invention, a set of tree-like dendritic crystals were grown on a micro-perforated plate to a height of 3 mm and a set of dendritic crystals were grown on a micro-perforated plate to a height of 10 mm. From the chart it can be seen that after 30 minutes, the 3 mm dendritic crystals were at the lowest temperature (temperature: 78.4° C.), the 10 mm dendritic crystals were at the next lowest temperature (temperature: 79.6° C.), and the heat dissipation effect of the copper plated micro-perforated plate and the thick copper plated micro-perforated plate were inferior compared to the pure micro-perforated plates, reaching temperatures of 85.7 and 83.9° C. respectively after 30 minutes.
Referring to Table 1, which discloses thermal resistance values and heat transfer factors of various test pieces compared to those of the dendritic crystal structure of the present invention. The thermal resistance values of an aluminum plate and a micro-perforated plates were 12.35 and 12.10° C./W respectively, and the thermal resistance values of 3 mm and 10 mm dendritic crystals grown on a micro-perforated plate according to the present invention were 9.90 and 9.58° C./W, respectively. The copper plated micro-perforated plates were plated for a period of 30 min and 180 min, respectively, and the respective thermal resistance values were 11.50 and 10.55° C./W. By comparing the differences in thermal resistance values, it can be seen that the thermal resistance values of dendritic crystals grown on a micro-perforated plates according to the present invention are relatively lower. Wherein the preferred optimum is 10 mm.

TABLE 1

Thermal resistance values and heat transfer factors of various
test pieces and the dendritic crystal structure of the present invention:

			Temperature
			difference
		Heat	between heat		Thermal
		dissipation	dissipation plate	Heat transfer	resistance
	Environment	plate	and environment	factor	value
Test piece	(° C.)	(° C.)	ΔT (° C.)	K (W/m * ° C.)	R (° C./W)

Aluminum plate	26	75.4	49.4	22.49	12.35
Micro-perforated	25.3	73.7	48.4	22.96	12.10
plate
Dendritic crystal	26.3	64.6	39.3	29.01	9.58
growth (10 mm)
Dendritic crystal	25.3	64.9	39.6	28.06	9.90
growth (3 mm)
Copper plating	25.6	67.8	42.2	26.33	10.55
(180 min)
Copper plating	25.9	71.9	46	24.15	11.50
(30 min)

A thermal imager was further used to film and view the temperature distribution and further analyze the heat dissipation situation and effective radial areas of dendritic copper crystals.
Referring first to FIG. 10, from viewing this diagram it can be seen that there exists a temperature difference between the surfaces of the dendritic crystals and the ambient temperature, and this temperature difference diffuses outward by means of a temperature gradient. Temperature variation data extending along the direction of Li1 of FIG. 10 serve to produce the graph of FIG. 11. From FIG. 11 it can be seen that there is a gradual diffusion outward of temperature, and that the temperature is separated into three stages. It can be seen from FIG. 11 that the curve gradually flattens after exceeding 0.5 mm. Furthermore, in FIG. 10, the thermal image of hot air shows there is no swaying phenomena resulting from air flow. A confirmatory experiment under a windless state also showed that the quantity of heat from the surfaces of the dendritic crystals heated the surrounding air via convection means, with the temperature gradually falling towards the exterior to achieve a heat dissipation effect.
Referring further to FIG. 12, which shows the heat transfer situation of a single dendritic crystal of length 2.3 mm, wherein the temperature change data extending along the line Li1 of FIG. 12 serve to produce the graph of FIG. 13. From FIG. 13 it can be seen that in the narrowest places of the dendritic crystals, because the heat dissipation area is restricted, thus, the deposition of temperature in these areas results in the inability to dissipate the temperature from these areas, whereas the relatively wider dendritic crystals enable the deposition of temperature and dissipation thereof.
Referring further to FIG. 14, which shows the heat transfer situation of a single dendritic crystal of length 0.75 mm, wherein the temperature change data extending along the line Li1 of FIG. 14 serve to produce the graph of FIG. 15. From FIG. 15 it can be seen that the smaller widths of the dendritic crystals causes temperature deposition.
Referring further to FIG. 16, which shows the heat transfer situation between two dendritic crystals, wherein the temperature change data extending along the line Li1 of FIG. 16 serve to produce the graph of FIG. 17. From FIG. 16 and FIG. 17 it can be inferred that a space is required between two sides of the dendritic crystals to achieve a heat transfer effect. If the interspace is too small, then it will affect the heat transfer area and be unable to completely discharge the heat provided by the heat source, thereby producing a thermal deposition phenomena. Furthermore, the widths of the single dendritic crystals should be consistent when transferring heat, because if some of the widths are somewhat smaller, then a deposition of temperature occurs at these areas causing an inferior heat dissipation effect.
As additional remarks, the laboratory apparatus used in the present invention include a thermal imager camera and a scanning electron microscope (SEM). Regarding specifications of the thermal imager camera: an infrared detector and an optical imaging lens are used to absorb the infrared radiation energy distribution of a test piece, whereupon an image forms on a photosensitive element of the infrared detector, from which is obtained an infrared thermograph. This thermograph and thermal field distribution of the test piece mutually correspond. Laboratory experiments carried out for the present invention used two thermal imagers for analysis, which separately analyzed macroscopic views and microscopic views to understand heat transfer situations and convection phenomena.

TABLE 2

Specifications of the thermal image analyzer used in the
laboratory experiments carried out for the present invention

	NEC-F30W	FLIR SC325 + FOL18

Resolution	160 × 120	320 × 240
Measurement range	20~350° C.	−20~300° C.
Manufacturer	Ching Hsing	Precision
	Computer-Tech	International Corp.
	Ltd.
Analysis mode	Macroscopic	Macroscopic view
	view	and microscopic
		view

TABLE 3

Specifications of the scanning electron microscope used in the
present invention

	Specifications	Hitachi S3000N

	Secondary electron	>3.5 nm (30 kV, high vacuum)
	resolution	>10 nm (3 kV, low vacuum)
	Backscattering electron	>5.0 nm (30 kV, low vacuum)
	resolution
	Amplification factor	20x~300000x
	Accelerating voltage	0.5~30 kV
	Resolution	640 × 480~5120 × 3840 pixels

In conclusion, the aforementioned description of the embodiments provide a complete understanding of the operation, use, and effectiveness of the present invention.
It is of course to be understood that the embodiments described herein are merely illustrative of the principles of the invention and that a wide variety of modifications thereto may be effected by persons skilled in the art without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

What is claimed is:

1. A growth method of dendritic crystal structure that provides directional heat transfer, comprising the following steps:

a) providing a substrate, whereby the substrate is provided with a plurality of crystal defects separated at intervals;

b) depositing a plurality of metal ions on the substrate using a deposition method, whereby the metal ions on the crystal defects enable the growth of dendritic crystals, and an interspace is provided between each of the dendritic crystals.

2. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein in step (a), processing is carried out on the substrate to form the crystal defects.

3. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 2, wherein the processing includes a cutting process.

4. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein in step (a), the substrate is plated with a whisker layer, and material of the coated whisker layer is any or a combination of tin, cadmium, zinc, antimony, or indium; the plurality of whiskers formed on the substrate serve as crystal defects.

5. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein in step (b), the substrate serves as an electrode for electroplating, wherein the electroplating current density is 1 A/dm²˜5 A/dm², and the electroplating time is 60 min˜180 min.

6. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein a length of the dendritic crystals is 0.1 mm˜15 mm.

7. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein a length of the dendritic crystals is 1 mm˜5 mm.

8. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein the interspace between each of the dendritic crystals is at least 0.1 mm˜0.5 mm.

9. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein in step (a), a cover member having poor electrical conductivity is disposed at a predetermined position on the substrate, thereby preventing the growth of dendritic crystals at the predetermined position.

10. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein density of dendritic crystals on the substrate is 3/cm²˜15/cm².

11. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein the substrate is an electrically conductive metal; in step (b), the substrate is first cleaned through pre-processing; the pre-processing includes a degreasing procedure used to remove grease and a sensitization procedure; the sensitization procedure includes soaking the substrate in an acidic solution to increase adhesion effect of the metal ions when carrying out electroplating.

12. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, which further comprises a step (c), wherein the substrate and the dendritic crystals are plated with an anti-oxidation layer.

13. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 1, wherein in step (b), the substrate serves as an electrode for electroplating, temperature condition for electroplating is 30° C.˜60° C., electroplating time is 2 hours, current density is 2.8 A/dm²˜8 A/dm², and the substrate is soaked in a copper plating solution with a pH value of 0˜2.5.

14. The growth method of dendritic crystal structure that provides directional heat transfer according to claim 13, wherein in step (b), the substrate serves as an electrode for electroplating, the temperature condition for electroplating is 30° C.˜60° C., electroplating time is 2 hours, current density is 2.8 A/dm²˜8 A/dm², and the substrate is soaked in in a copper plating solution with a pH value of 1.45 and a specific weight of 1.190.