LIQUID-COOLING COOLER HAVING NICKEL MULTILAYER STRUCTURE

Description

FIELD OF THE DISCLOSURE

The present disclosure relates to a liquid-cooling cooler, and more particularly to a liquid-cooling cooler having a nickel multilayer structure.

BACKGROUND OF THE DISCLOSURE

In the current marketplace, there is an increasingly high requirement on the reliability of a liquid-cooling cooler for an automotive insulated-gate bipolar transistor (IGBT) or automotive advanced driver-assistance systems (ADAS). High corrosion resistance and high solderability are required. In order to enhance the corrosion resistance, a phosphorus content is to be increased. On the other hand, the phosphorus content needs to be decreased for enhancement of solderability. Due to this dilemma, a high-phosphorus electroless nickel plating surface of the current liquid-cooling cooler fail to meet the requirements.

SUMMARY OF THE DISCLOSURE

In response to the above-referenced technical inadequacies, the present disclosure provides a liquid-cooling cooler having a nickel multilayer structure.

In order to solve the above-mentioned problems, one of the technical aspects adopted by the present disclosure is to provide a liquid-cooling cooler having a nickel multilayer structure, which includes a liquid-cooling cooler body and the nickel multilayer structure. The nickel multilayer structure is formed on the liquid-cooling cooler body for bonding with at least one heat source. A topmost layer of the nickel multilayer structure is a pure nickel electroplating layer, and a nickel content of the pure nickel electroplating layer is greater than 99 wt %. An electroless nickel-phosphorus plating layer is disposed beneath the pure nickel electroplating layer, and a phosphorus content of the electroless nickel-phosphorus plating layer ranges between 6 wt % and 13 wt %. The liquid-cooling cooler body is made of a non-nickel metal. A thickness of the pure nickel electroplating layer is less than or equal to 2 μm, and a thickness of the electroless nickel-phosphorus plating layer ranges between 3 μm and 12 μm.

In one of the possible or preferred embodiments, the liquid-cooling cooler body is made of a copper alloy, aluminum, or an aluminum alloy.

In one of the possible or preferred embodiments, a pure nickel flash plating layer is further formed between the liquid-cooling cooler body and the electroless nickel-phosphorus plating layer, and a nickel content of the pure nickel flash plating layer is greater than 99 wt %.

In one of the possible or preferred embodiments, an anti-oxidation sealing layer is further formed on the pure nickel electroplating layer that is the topmost layer of the nickel multilayer structure.

In one of the possible or preferred embodiments, the pure nickel electroplating layer and the electroless nickel-phosphorus plating layer of the nickel multilayer structure are each a matte nickel layer without addition of a brightening agent.

In one of the possible or preferred embodiments, gold, tin, silver, or alloying elements thereof are absent between the liquid-cooling cooler body and the nickel multilayer structure, and are absent in and above the nickel multilayer structure.

These and other aspects of the present disclosure will become apparent from the following description of the embodiment taken in conjunction with the following drawings and their captions, although variations and modifications therein may be affected without departing from the spirit and scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The described embodiments may be better understood by reference to the following description and the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of a partial structure according to a first embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view of the partial structure according to a second embodiment of the present disclosure; and

FIG. 3 is a schematic cross-sectional view of the partial structure according to a third embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The present disclosure is more particularly described in the following examples that are intended as illustrative only since numerous modifications and variations therein will be apparent to those skilled in the art. Like numbers in the drawings indicate like components throughout the views. As used in the description herein and throughout the claims that follow, unless the context clearly dictates otherwise, the meaning of “a,” “an” and “the” includes plural reference, and the meaning of “in” includes “in” and “on.” Titles or subtitles can be used herein for the convenience of a reader, which shall have no influence on the scope of the present disclosure.

The terms used herein generally have their ordinary meanings in the art. In the case of conflict, the present document, including any definitions given herein, will prevail. The same thing can be expressed in more than one way. Alternative language and synonyms can be used for any term(s) discussed herein, and no special significance is to be placed upon whether a term is elaborated or discussed herein. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms is illustrative only, and in no way limits the scope and meaning of the present disclosure or of any exemplified term. Likewise, the present disclosure is not limited to various embodiments given herein. Numbering terms such as “first,” “second” or “third” can be used to describe various components, signals or the like, which are for distinguishing one component/signal from another one only, and are not intended to, nor should be construed to impose any substantive limitations on the components, signals or the like.

First Embodiment

Reference is made to FIG. 1, which is a schematic cross-sectional view of a partial structure according to a first embodiment of the present disclosure. The present embodiment provides a liquid-cooling cooler having a nickel multilayer structure. The liquid-cooling cooler of the present embodiment includes a liquid-cooling cooler body 10 and a nickel multilayer structure 20.

The liquid-cooling cooler body 10 is made of a non-nickel metal. The liquid-cooling cooler body 10 can be made of copper, a copper alloy, aluminum, or an aluminum alloy having a high heat dissipation property. In addition, the liquid-cooling cooler body 10 can be a liquid-cooling plate or a liquid-cooling block having channels formed therein.

The nickel multilayer structure 20 is formed on the liquid-cooling cooler body 10 for bonding with a heat source. Through soldering and use of little or no flux, the nickel multilayer structure 20 can be bonded with the heat source. The heat source can be an electric vehicle power module, and the electric vehicle power module can be an IGBT module or an automotive ADAS module.

In the present embodiment, a topmost layer of the nickel multilayer structure 20 is a pure nickel electroplating layer 201, and a nickel content of the pure nickel electroplating layer 201 is greater than 99 wt %. An electroless nickel-phosphorus plating layer 202 is disposed beneath the pure nickel electroplating layer 201, and a phosphorus content of the electroless nickel-phosphorus plating layer 202 ranges between 6 wt % and 13 wt %. A thickness of the pure nickel electroplating layer 201 is less than or equal to 2 μm, and is preferably 1 μm. A thickness of the electroless nickel-phosphorus plating layer 202 ranges between 3 μm and 12 μm. That is, the thickness of the electroless nickel-phosphorus plating layer 202 is greater than the thickness of the pure nickel electroplating layer 201. Moreover, the pure nickel electroplating layer 201 can be partially formed on the electroless nickel-phosphorus plating layer 202.

Through a solder ball wetting test (in which a formic acid reflow oven and a flux-free solder ball are used), a high-phosphorus electroless nickel plating surface of an existing liquid-cooling cooler has a wetting angle of about 65 degrees relative to the solder ball. However, in the liquid-cooling cooler of the present embodiment, a surface of the nickel multilayer structure 20 has a wetting angle of about 42.9 degrees relative to the solder ball, thereby having better solderability. Since the topmost layer of the nickel multilayer structure 20 in the liquid-cooling cooler is the pure nickel electroplating layer 201 that has a nickel content of greater than 99 wt % and a thickness of less than or equal to 2 μm, and the electroless nickel-phosphorus plating layer 202 that has a phosphorus content ranging between 6 wt % and 13 wt % and a thickness ranging between 3 μm and 12 μm is disposed beneath the pure nickel electroplating layer 201, the requirements on enhanced solderability and corrosion resistance can be satisfied at the same time.

Furthermore, through the solder ball wetting test, the surface of the nickel multilayer structure 20 in the liquid-cooling cooler has a wetting angle of about 44.8 degrees relative to the solder ball when the pure nickel electroplating layer 201 has a minimum thickness of 0.5 μm. That is, the pure nickel electroplating layer 201 can be extremely thin but still achieves a soldering effect similar to that of the pure nickel electroplating layer 201 having a slightly larger thickness, thereby allowing time and costs for electroplating to be significantly reduced.

Second Embodiment

Reference is made to FIG. 2, which is a schematic cross-sectional view of the partial structure according to a second embodiment of the present disclosure. The present embodiment is substantially the same as the first embodiment, and differences therebetween are as follows.

In the present embodiment, a pure nickel flash plating layer 203 is further formed between the liquid-cooling cooler body 10 and the electroless nickel-phosphorus plating layer 202. That is, a bottommost layer of the nickel multilayer structure 20 is the pure nickel flash plating layer 203, and a nickel content of the pure nickel flash plating layer 203 is greater than 99 wt %. By forming the extremely-thin pure nickel flash plating layer 203 on a surface of the liquid-cooling cooler body 10, and then forming the electroless nickel-phosphorus plating layer 202 on the pure nickel flash plating layer 203, the problem of poor bonding between the electroless nickel-phosphorus plating layer 202 (after plating) and the surface of the liquid-cooling cooler body 10 can be effectively solved, such that a product yield can be effectively improved.

The liquid-cooling cooler of the present embodiment is a cooler that does not contain gold, tin, silver, or alloying elements thereof. That is, the liquid-cooling cooler body 10 and the nickel multilayer structure 20 of the liquid-cooling cooler do not contain gold, tin, silver, or alloying elements thereof. Specifically, gold, tin, silver, or alloying elements thereof are absent between the liquid-cooling cooler body 10 and the nickel multilayer structure 20, and are also absent in and above the nickel multilayer structure 20.

Third Embodiment

Reference is made to FIG. 3, which is a schematic cross-sectional view of the partial structure according to a third embodiment of the present disclosure. The present embodiment is substantially the same as the first and the second embodiment, and differences therebetween are as follows.

In the present embodiment, an anti-oxidation sealing layer 30 is further formed on the nickel multilayer structure 20. In other words, the anti-oxidation sealing layer 30 is further formed on the pure nickel electroplating layer 201 that is the topmost layer of the nickel multilayer structure 20, and a thickness of the anti-oxidation sealing layer 30 is less than 0.5 μm. In addition, the anti-oxidation sealing layer 30 can be formed by organic compounds, such as glycol ethers and thiols. By further forming the anti-oxidation sealing layer 30 on the pure nickel electroplating layer 201 that is the topmost layer of the nickel multilayer structure 20, oxidation of the pure nickel electroplating layer 201 can be delayed, thereby preventing oxidation from affecting solderability.

Furthermore, the pure nickel electroplating layer 201 and the electroless nickel-phosphorus plating layer 202 of the nickel multilayer structure 20 are each a matte nickel layer without addition of a brightening agent, thereby preventing bright nickel from affecting solderability.

Beneficial Effects of the Embodiments

In conclusion, the liquid-cooling cooler having the nickel multilayer structure provided by the present disclosure includes the liquid-cooling cooler body and the nickel multilayer structure. The nickel multilayer structure is formed on the liquid-cooling cooler body for bonding with at least one heat source. The topmost layer of the nickel multilayer structure is the pure nickel electroplating layer, and the nickel content of the pure nickel electroplating layer is greater than 99 wt %. The electroless nickel-phosphorus plating layer is disposed beneath the pure nickel electroplating layer, and the phosphorus content of the electroless nickel-phosphorus plating layer ranges between 6 wt % and 13 wt %. The liquid-cooling cooler body is made of the non-nickel metal. The thickness of the pure nickel electroplating layer is less than or equal to 2 μm, and the thickness of the electroless nickel-phosphorus plating layer ranges between 3 μm and 12 μm. Since the topmost layer of the nickel multilayer structure in the liquid-cooling cooler is the pure nickel electroplating layer that has a nickel content of greater than 99 wt % and a thickness of less than or equal to 2 μm, and the electroless nickel-phosphorus plating layer 202 that has a phosphorus content ranging between 6 wt % and 13 wt % and a thickness ranging between 3 μm and 12 μm is disposed beneath the pure nickel electroplating layer 201, the requirements on enhanced solderability and corrosion resistance can be satisfied at the same time.

The foregoing description of the exemplary embodiments of the disclosure has been presented only for the purposes of illustration and description and is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in light of the above teaching.

The embodiments were chosen and described in order to explain the principles of the disclosure and their practical application so as to enable others skilled in the art to utilize the disclosure and various embodiments and with various modifications as are suited to the particular use contemplated. Alternative embodiments will become apparent to those skilled in the art to which the present disclosure pertains without departing from its spirit and scope.