A high-strength electroplated porous copper liquid wick and its preparation method and application

Abstract

The present invention discloses a high-strength electroplated porous copper liquid-absorbing core and its preparation method and application. The liquid-absorbing core has a stacked double-layer configuration. The micro-nano porous copper layer and the copper / ceramic particle composite reinforcement layer have complementary performance advantages. The dispersion strengthening effect of the ceramic particles can improve the strength of the porous copper layer, thereby increasing the bonding strength with the substrate, reducing shedding, and improving stability. The liquid-absorbing core is generated by an electrodeposition reaction on a cover plate such as a heat spreader, which helps reduce the manufacturing difficulty and facilitates the mass production of heat spreaders and other structures.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular to a high-strength electroplated porous copper liquid-absorbing core and a preparation method and application thereof. Background Art

[0002] The wick is the most core component of heat pipes and heat spreaders. Currently, commonly used wicks include copper mesh, copper powder, etc. However, the molding of the wick requires high-temperature heat treatment, and the process is relatively complicated. In addition, the copper mesh and the lower cover must be firmly welded to achieve a good heat dissipation effect. It is extremely difficult to manufacture ultra-thin heat pipes and heat spreaders.

[0003] In this regard, some researchers have tried to form liquid-absorbing wicks through electrodeposition. For example, the porous copper layer uses the hydrogen bubbles released from the cathode during the electrodeposition process as a template, and the porous liquid-absorbing wick coating can be grown in situ on the metal substrate. The obtained coating has high porosity and high capillary properties, and has great application potential in the field of ultra-thin heat pipes and heat sinks.

[0004] However, the weak bonding force between the coating and the substrate makes the coating extremely easy to fall off, and the stability is insufficient, which still needs to be improved. Summary of the Invention

[0005] To solve at least one of the above technical deficiencies, the present invention provides the following technical solutions:

[0006] The first aspect of the present application document discloses a high-strength electroplated porous copper wick, which comprises a micro-nano porous copper layer and a copper / ceramic particle composite reinforcement layer stacked sequentially in the thickness direction, wherein the copper / ceramic particle composite reinforcement layer is located on the outer surface, the micro-nano porous copper layer is generated by an electrodeposition reaction, and the copper / ceramic particle composite reinforcement layer is generated on the micro-nano porous copper layer by an electrodeposition reaction.

[0007] In this scheme, the liquid-absorbing core has a stacked double-layer configuration, in which the micro-nano porous copper layer has high water storage capacity and high capillary climbing properties. The ceramic particles in the copper / ceramic particle composite reinforcement layer have a dispersion strengthening effect, which can increase the strength of the porous copper layer, thereby improving the bonding strength between the porous copper layer and the substrate (such as the cover plate in the heat spreader), reducing shedding phenomenon, and improving stability.

[0008] Furthermore, the pore size of the micro-nano porous copper layer is 0.01-100μm, the thickness is 10-200μm, and the porosity is 20-90%; the particle size of the ceramic particles in the copper / ceramic particle composite strengthening layer is 50nm-5μm, the thickness is 2-20μm, and the ceramic particles are any one or more combinations of aluminum oxide, aluminum nitride, silicon oxide, silicon nitride, silicon carbide, zirconium oxide, and tungsten carbide. The thickness, porosity, and pore size parameters of the micro-nano porous copper layer, as well as the thickness of the copper / ceramic particle composite strengthening layer and the type and particle size of the ceramic particles are preferred, which help to further improve the performance of the liquid-absorbing core.

[0009] The second aspect of this application document discloses a method for preparing a high-strength electroplated porous copper wick, comprising the following steps:

[0010] First, electroplating is performed using the substrate as the cathode to generate a micro-nano porous copper layer on the substrate through an electrodeposition reaction;

[0011] Second, the substrate with the micro-nano porous copper layer is subjected to secondary electroplating at the cathode, and a copper / ceramic particle composite reinforcement layer is formed on the micro-nano porous copper layer by electrodeposition reaction, and a liquid wick having the micro-nano porous copper layer and the copper / ceramic particle composite reinforcement layer is formed.

[0012] The porous copper layer is grown in situ on the substrate through the electrodeposition reaction, and the copper / ceramic particle composite reinforcement layer is grown overlying the porous copper layer through the electrodeposition reaction. In combination, the bonding strength between the porous copper layer and the substrate is improved and the shedding phenomenon is reduced. This process is suitable for mass production.

[0013] Furthermore, in the first step, the electroplating solution includes 2-20 wt% of copper salt and 5-20 wt% of acid; the electrodeposition reaction conditions are: the current density is 5-200 A / dm 2 , temperature is 30-40℃, time is 5-300s.

[0014] Furthermore, the copper salt is any one of copper sulfate and copper chloride or a combination of both; the acid is any one of sulfuric acid and hydrochloric acid or a combination of both.

[0015] Furthermore, in the second step, the electroplating solution includes 2-20 wt% of copper salt, 5-20 wt% of acid and 0.05-5 wt% of ceramic particles; the electrodeposition reaction conditions are: the current density is 0.5-20 A / dm 2 , temperature is 15-30℃, time is 2-30min.

[0016] Furthermore, the copper salt is any one of copper sulfate and copper chloride or a combination of both; the acid is any one of sulfuric acid and hydrochloric acid or a combination of both.

[0017] The third aspect of this application document discloses the application of the above-mentioned liquid wick in heat pipes and heat sinks.

[0018] Furthermore, it is applied to heat spreaders: during electroplating, the cover plate in the heat spreader is used as the substrate, and a micro-nano porous copper layer is generated on the cover plate through an electrodeposition reaction, which helps to reduce the manufacturing difficulty and enables mass production of heat spreaders.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention designs a liquid-absorbing core structure with a stacked double-layer configuration. The micro-nano porous copper layer and the copper / ceramic particle composite reinforcement layer complement each other in performance. The dispersion strengthening effect of the ceramic particles can improve the strength of the porous copper layer, thereby improving the bonding strength between the porous copper layer and the substrate, reducing shedding and improving stability.

[0021] 2. In the heat spreader of the present invention, a porous copper layer is generated on the cover plate through an electrodeposition reaction, and a copper / ceramic particle composite reinforcement layer is formed on the porous copper layer through an electrodeposition reaction. The porous copper layer is reinforced with ceramic particles dispersed therein, which helps to improve the bonding strength between the porous copper layer and the cover plate, reduces the manufacturing difficulty, and facilitates the mass production of heat spreaders. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 These are SEM morphology images of the porous coating with a strengthening layer and the porous copper plating layer without a strengthening layer constructed in Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1

[0026] The vapor chamber was prepared as follows:

[0027] (1) Pre-treat the stainless steel cover plate in the soaking plate (conventional surface cleaning), then immerse the stainless steel cover plate and phosphor copper sheet in the electroplating solution to form an electrochemical working system with the stainless steel cover plate as the cathode and the phosphor copper sheet as the anode; turn on the power supply and apply a current density of 5A / dm between the anode and the cathode. 2The electroplating reaction was carried out at 30°C for 300 seconds, producing a porous copper coating with a micro-nanostructure. The resulting stainless steel cover plate had a micro-nanoporous copper layer with a thickness of 30 μm. The electroplating solution consisted of 2 wt% copper sulfate, 5 wt% sulfuric acid, and the remainder water.

[0028] (2) Immerse the stainless steel cover plate with porous copper and the phosphor copper sheet prepared in step (1) in a second electroplating solution to form an electrochemical working system with the stainless steel cover plate with the micro-nano porous copper layer as the cathode and the phosphor copper as the anode; turn on the power supply and apply a current density of 0.5A / dm between the anode and the cathode. 2 The electrodeposition reaction was carried out at 15°C for 30 minutes at a current of 1000 rpm, resulting in a 5μm-thick copper / ceramic particle composite reinforcement layer conformally grown along the surface of the micro-nanoporous copper layer. The plating solution consisted of 2wt% copper sulfate, 5wt% sulfuric acid, 0.05wt% alumina particles with an average particle size of 50nm, and the remainder water.

[0029] After testing, the water contact angle of the surface of the composite material prepared in this embodiment is 0°; the stainless steel lower cover and the cover plate containing the wick are packaged to form a heat spreader. After the wick is packaged, the temperature difference between any two points on the surface under a 5W test power is less than 3°C, and the total thickness of the heat spreader is 0.3mm.

[0030] Example 2

[0031] The vapor chamber was prepared as follows:

[0032] (1) Pre-treat the copper cover plate in the heat spreader (conventional surface cleaning), immerse the pre-treated copper cover plate and phosphor copper sheet in the electroplating solution to form an electrochemical working system with the copper cover plate as the cathode and the phosphor copper as the anode; turn on the power supply and apply a current density of 200A / dm between the anode and the cathode. 2 The electroplating solution consisted of 20 wt% copper chloride, 20 wt% hydrochloric acid, and the remainder water.

[0033] (2) Immerse the copper cover plate with the micro-nano porous copper layer and the phosphor copper sheet prepared in step (1) in an electroplating solution to form an electrochemical working system with the copper cover plate with the micro-nano porous copper layer as the cathode and the phosphor copper as the anode; connect the power supply and apply a current density of 20A / dm between the anode and the cathode. 2 The electrodeposition reaction was carried out at 30°C for 2 minutes, resulting in a 15μm-thick copper / ceramic particle composite reinforcement layer conformally grown along the surface of the micro-nanoporous copper layer. The plating solution consisted of 20wt% copper chloride, 20wt% hydrochloric acid, 5wt% tungsten carbide particles with an average particle size of 5μm, and the remainder water.

[0034] After testing, the water contact angle of the surface of the composite material prepared in this embodiment is 0°; a copper sheet is used as the lower cover of the heat spreader, and the lower cover and the cover plate containing the liquid wick are encapsulated to form a heat spreader. After the liquid wick is encapsulated, the temperature difference between any two points on the surface under a 5W test power is less than 3°C, and the total thickness of the heat spreader is 0.4mm.

[0035] Example 3

[0036] The vapor chamber was prepared as follows:

[0037] (1) Pre-treat the titanium alloy cover plate in the soaking plate (conventional surface cleaning), immerse the pre-treated titanium alloy cover plate and phosphor copper sheet in the electroplating solution to form an electrochemical working system with the titanium alloy cover plate as the cathode and the phosphor copper as the anode; turn on the power supply and apply a current density of 100A / dm between the anode and the cathode. 2 The electroplating solution consisted of 10 wt% copper sulfate, 10 wt% hydrochloric acid, and the remainder water.

[0038] (2) Immerse the titanium alloy cover plate with the micro-nano porous copper layer and the phosphor copper sheet prepared in step (1) in an electroplating solution to form an electrochemical working system with the titanium alloy cover plate with the micro-nano porous copper layer as the cathode and the phosphor copper as the anode; turn on the power supply and apply a current density of 5A / dm between the anode and the cathode. 2 The electroplating reaction was carried out at 20°C for 10 minutes, yielding a 12μm thick copper / ceramic particle composite reinforcement layer that conformally grew along the surface of the micro-nanoporous copper layer. The plating solution consisted of 10wt% copper sulfate, 10wt% hydrochloric acid, 2wt% silicon carbide particles with an average particle size of 1μm, and the remainder water.

[0039] After testing, the water contact angle of the surface of the composite material prepared in this embodiment is 0°; a titanium alloy sheet is used as a lower cover, and the lower cover and the cover plate containing the liquid wick are encapsulated to form a heat spreader. After the liquid wick is encapsulated, the temperature difference between any two points on the surface under a 5W test power is less than 3°C, and the total thickness of the heat spreader is 0.25mm.

[0040] Comparative Example 1: The difference between this comparative example and Example 1 is that there is no copper / ceramic particle composite strengthening layer.

[0041] The coating prepared in this comparative example did not have a strengthening layer, and the coating fell off during the vapor chamber packaging process, and a good vapor chamber could not be obtained.

[0042] Comparative Example 2: The difference between this comparative example and Example 1 is that no micro-nano porous copper layer is constructed.

[0043] The composite material prepared in this comparative example does not have a porous layer and does not have a capillary effect, and therefore cannot be used as a liquid wick for a vapor chamber.

[0044] Comparative Example 3: The difference between this comparative example and Example 1 is that no ceramic particles are added to the copper / ceramic particle composite strengthening layer.

[0045] The strengthening layer prepared in this comparative example does not have the dispersion strengthening effect of ceramic particles, and substantially does not play a strengthening and protective role on the porous copper. The coating falls off during the vapor chamber packaging process, and a good vapor chamber cannot be obtained.

[0046] At the same time, the high-strength electroplated porous copper wick material obtained in Example 1 was taken as an example, and its characterization was carried out: Figure 1 As shown, it can be seen that the ceramic particles in the copper / ceramic particle composite strengthening layer can effectively strengthen the micro-nano porous copper layer.

[0047] The vapor chamber prepared in Example 1 was subjected to an aging performance test at a test temperature of 90° C., as shown in Table 1.

[0048] Table 1: Aging performance test data

[0049]

[0050] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that improvements and modifications that do not depart from the principles of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength electroplated porous copper wick, characterized in that: The wick comprises a micro-nano porous copper layer and a copper / ceramic particle composite reinforcement layer stacked in sequence in the thickness direction, wherein the copper / ceramic particle composite reinforcement layer is located on the outer surface, the micro-nano porous copper layer is formed by an electrodeposition reaction, and the copper / ceramic particle composite reinforcement layer is formed on the micro-nano porous copper layer by an electrodeposition reaction; The preparation method of the wick comprises the following steps: First, electroplating is performed using the substrate as the cathode to generate a micro-nano porous copper layer on the substrate through an electrodeposition reaction; Second, the substrate formed with the micro-nano porous copper layer is subjected to secondary electroplating at a cathode, and a copper / ceramic particle composite reinforcement layer is formed by an electrodeposition reaction on the micro-nano porous copper layer, and a liquid wick having the micro-nano porous copper layer / copper / ceramic particle composite reinforcement layer is formed; In the first step, the electroplating solution includes 2-20 wt% of copper salt and 5-20 wt% of acid; the electrodeposition reaction conditions are: current density of 5-200 A / dm2, temperature of 30-40°C, and time of 5-300 s; In the second step, the electroplating solution includes 2-20 wt% of copper salt, 5-20 wt% of acid and 0.05-5 wt% of ceramic particles; the electrodeposition reaction conditions are: current density of 0.5-20 A / dm2, temperature of 15-30°C, and time of 2-30 minutes; The ceramic particles are any one or more combinations of aluminum oxide, aluminum nitride, silicon oxide, silicon nitride, silicon carbide, zirconium oxide, and tungsten carbide.

2. The method for preparing a high-strength electroplated porous copper wick according to claim 1, wherein: The pore size of the micro-nano porous copper layer is 0.01-100 μm, the thickness is 10-200 μm, and the porosity is 20-90%; the particle size of the ceramic particles in the copper / ceramic particle composite strengthening layer is 50 nm-5 μm, and the thickness is 2-20 μm.

3. The method for preparing a high-strength electroplated porous copper wick according to claim 1, wherein: The copper salt is any one of copper sulfate and copper chloride or a combination of the two; the acid is any one of sulfuric acid and hydrochloric acid or a combination of the two.

4. The method for preparing a high-strength electroplated porous copper wick according to claim 1, wherein: The copper salt is any one of copper sulfate and copper chloride or a combination of the two; the acid is any one of sulfuric acid and hydrochloric acid or a combination of the two.

5. Use of the liquid wick prepared according to claim 1 in heat pipes and heat sinks.

6. The use according to claim 5, characterized in that: Application in heat spreader: During electroplating, the cover plate in the heat spreader is used as the substrate, and a micro-nano porous copper layer is generated on the cover plate through electrodeposition reaction.

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