JP2021163898A - Method for manufacturing metal structure - Google Patents

Abstract

To provide a method for manufacturing a metal structure including a plurality of salients.SOLUTION: A metal structure 10 comprises a base part 12 and a plurality of fins 14. A method for manufacturing the metal structure 10 includes at least a metal layer forming step and an etching step. The metal layer forming step forms a copper layer 34 on at least one surface of a glass substrate 20 and in a salient formation schedule unit including a thorough hole 22 formed on the surface of the glass substrate. The etching step dissolves the glass substrate 20 in which a copper layer 34 is formed by bringing the glass substrate into contact with an etchant.SELECTED DRAWING: Figure 5

Description

The present invention relates to a method for manufacturing a metal structure having a plurality of convex portions.

Among the circuit boards on which semiconductor elements are mounted, power module boards are being actively developed for power supply. Further, since a large amount of electric power is supplied to this power module board, the amount of heat generated is relatively high. Therefore, a heat sink is actively used as a heat dissipation measure for the power module substrate.

The heat sink is a metal structure provided with a heat radiating member called a fin on the substrate. A metal having excellent heat dissipation such as aluminum or copper is often used for the heat sink. The fins are provided in a rod-shaped or plate-shaped shape depending on the heat radiating member, the arrangement location, and the like.

A method of manufacturing a heat sink by a forging method using a die has conventionally existed (see, for example, Patent Document 1). According to this method, pin-shaped fins are formed by flowing the material through the holes provided in the mold. It is said that the use of a mold makes it possible to simplify the manufacture of a heat sink having pin-shaped fins and reduce the manufacturing cost.

Patent No. 6045381

However, in the case of manufacturing a pin-shaped fin having a high aspect ratio, the fin may be broken and damaged when the mold is pulled out. In particular, in the case of manufacturing an elongated and low-strength convex fin having a fin diameter of 100 μm or less, there is a high possibility that the pin will be damaged at the manufacturing stage even if a mold is used. Further, since creating a metal structure having a fine structure with a mold having a shape other than the pin-shaped fin may cause a problem at the time of die cutting, a new manufacturing method of the metal structure having a fine convex portion is performed. Was required.

An object of the present invention is to provide a method for manufacturing a metal structure having a plurality of convex portions.

The metal structure according to the present invention includes at least a metal base and a plurality of metal protrusions provided on the base. The method for producing a metal structure includes at least a metal layer forming step and an etching step. The metal layer forming step is a step of forming a metal layer on at least one surface of the glass substrate and a convex portion to be formed having holes, recesses or grooves formed on the surface of the glass substrate. The etching step is a step of melting a glass substrate on which a metal layer is formed by bringing it into contact with an etching solution.

The method for manufacturing a metal structure according to the present invention uses a glass substrate as a mold for forming a convex portion. Since the glass substrate can be removed without applying physical force in the etching step, the risk of damage to the metal material of the portion where the convex portion is to be formed is reduced. Further, the portion to be formed of the convex portion on the glass substrate can be formed into a desired shape by using the etching process, and can correspond to the convex portion having various shapes.

Further, it is preferable that the metal layer further includes a protective step for forming an etching resistant layer having resistance to the etching solution before the etching step. By forming the etching resistant layer on the metal layer, it is possible to prevent the metal layer from self-shrinking when the glass substrate is melted. This makes it possible to prevent deterioration of the surface quality of the metal structure.

Further, it is preferable to further include a pretreatment step of removing a part of the metal layer formed on the surface of the glass substrate before the etching step. By removing a part of the metal layer in the pretreatment step, the melting rate of the etching-treated glass substrate is increased, and the productivity is improved. Furthermore, the insoluble products generated during the etching process are prevented from adhering to the metal structure.

According to the present invention, it becomes possible to provide a method for manufacturing a metal structure having a plurality of convex portions.

It is a figure which shows the metal structure which concerns on one Embodiment of this invention. It is a figure which shows the process of forming a through hole in a glass substrate. It is a figure which shows the etching apparatus which etches a glass substrate. It is a figure which shows the manufacturing method of the metal structure which concerns on one Embodiment of this invention. It is a figure which shows the manufacturing method of the metal structure which concerns on one Embodiment of this invention. It is a figure which shows the metal structure and the glass substrate which concerns on other embodiment of this invention. It is a figure which shows the manufacturing method of the metal structure which concerns on other embodiment of this invention.

From here, an embodiment of the metal structure according to the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a metal structure 10 according to an embodiment of the present invention. The metal structure 10 is used as a heat sink and includes a base 12 and pin-shaped fins 14. The base portion 12 is a rectangular plate-shaped flat surface portion. The base 12 is a metal member made of an alloy containing at least copper. The metal material that can be used for the base 12 is not limited, and a desired metal material such as aluminum or silver can be used.

The fin 14 is a convex portion extending in the vertical direction from the base portion 12 and has a cylindrical shape. Like the base 12, the fin 14 is also a metal member made of an alloy containing copper, and is joined to the base 12. The diameter of the fin 14 is adjusted to 10 to 80 μm, and the height is adjusted to about 80 to 500 μm. The pitch of the fins 14 is adjusted to about 10 to 100 μm. The shape of the fin portion 14 can be formed into a linear or rectangular parallelepiped shape in addition to the cylindrical shape.

From here, a method of manufacturing the metal structure 10 will be described with reference to the drawings. The method for manufacturing the metal structure 10 includes a metal layer forming step, a masking step, a metal layer removing step, and an etching step.

The metal layer forming step is a step of forming a metal layer on a glass substrate on which a convex portion to be formed corresponding to a region where fins 14 are formed is formed. The glass substrate 20 on which the metal layer is formed is a rectangular glass substrate having dimensions corresponding to the heat sink. The type of glass substrate is not particularly limited, and non-alkali glass, aluminosilicate glass, quartz glass and the like can be used. Further, as shown in FIG. 2A, the glass substrate 20 has a through hole 22 corresponding to the portion to be formed of the convex portion described in the claims. The through hole 22 is a hole formed substantially perpendicularly from one main surface of the glass substrate 20 to the other main surface. The through holes 22 are configured to be filled with a metal material to be fins 14, and the glass substrate 20 is formed with a plurality of through holes 22 at predetermined intervals.

Here, a method of forming the through hole 22 will be described. The through hole 22 is formed by a laser step and an etching step. The laser step is a step of forming a modified region 30 having a property of being easily etched by an etching solution in the thickness direction of the glass substrate 20. As shown in FIGS. 2 (B) and 2 (C), the modified region 30 is a region in which a plurality of filaments 32 are formed in the plate thickness direction of the glass substrate 20. The filament 32 is formed by irradiating a laser beam emitted from a laser apparatus into a plurality of focal points at predetermined intervals in the plate thickness direction of the glass substrate 20. The output of the laser beam is adjusted, for example, in the range of 30 to 300 μmJ so as not to affect a region other than the modified region. The forming interval and the number of filaments 32 are adjusted according to the thickness of the glass substrate, the shape of the convex portion, and the like.

The etching step is a step of forming the through hole 22 by bringing the glass substrate 20 on which the modified region 30 is formed into contact with the etching solution. As a method of etching the glass substrate 20, for example, there is a method of using the etching apparatus 40 shown in FIGS. 3 (A) and 3 (B). The etching apparatus 40 is a spray etching apparatus configured to inject an etching solution onto a glass substrate 20 conveyed by a conveying roller. The etching apparatus 40 includes a plurality of etching chambers 42 for injecting an etching solution. The etching chamber 42 is configured to inject the etching solution from the vertical direction onto the glass substrate 20 which is conveyed in the horizontal direction. Since the cleaning chamber 44 for washing away the etching solution adhering to the glass substrate 20 is provided in the subsequent stage of the etching chamber 42, the glass substrate 20 is discharged from the etching apparatus 40 in a state where the etching solution is removed. NS. The etching solution contains at least hydrofluoric acid, and may contain an inorganic acid such as hydrochloric acid or sulfuric acid or a surfactant.

Due to the contact between the etching solution and the glass substrate 20, in the modified region 30 where the filament 32 is formed, etching is more likely to proceed in the plate thickness direction than in the peripheral region, and as shown in FIG. 2 (D), the aspect ratio It is possible to form a high-ratio (elongated) through hole 22. If necessary, the glass substrate 20 may be adjusted to a desired plate thickness by this etching process.

The method of forming the metal layer on the glass substrate 20 in which the through holes 22 are formed is performed by plating treatment techniques such as electroless plating, electrolytic plating, and strike plating, or a combination thereof. In this embodiment, the copper layer 34 is formed on the glass substrate 20 by using electroless plating. Electroless plating is performed by immersing a glass substrate in a known plating solution. An underlayer may be formed before the plating treatment for the purpose of improving surface characteristics such as adhesion of the plating layer.

As shown in FIG. 4A, the copper layer 34 is formed on both main surfaces of the glass substrate 20 and in the through holes 22. The copper layer 34 is formed so as to have a predetermined film thickness on the surface portion of the glass substrate 20. Further, the copper layer 34 is formed in the through hole 22 so as to fill the inside of the hole. Before the metal layer forming step, a protective film or the like may be used to cover a region where the copper layer 34 does not need to be formed.

The masking step is a step of forming an etching resistant layer having resistance to an etching solution on the copper layer 34. As the etching resistant layer, an ultraviolet peeling type protective film 36 is used. As shown in FIG. 4B, the protective film 36 is coated on one main surface of the glass substrate 20. By using the ultraviolet peeling type film, impurities such as an adhesive are prevented from adhering to the surface of the copper layer 34 at the time of film peeling.

The metal layer removing step is a step of removing the copper layer 34 formed on the surface of the glass substrate 20. In the metal layer removing step, the copper layer 34 formed on the main surface not covered with the protective film 36 is removed. The copper layer 34 can be removed by using an etching solution capable of dissolving copper such as ferric chloride, or by physically removing the copper layer 34 by mechanical polishing or the like. By performing the metal layer removing step, as shown in FIG. 4C, all the copper layers 34 formed on one main surface of the glass substrate 20 are removed. By removing unnecessary portions of the copper layer 34 before the etching process, the efficiency of the etching process can be improved. Further, it is also possible to prevent the reaction product generated by the reaction between the glass substrate and the etching solution during the etching process from adhering to the copper layer 34.

The etching step is a step of melting the entire glass substrate 20 by bringing the glass substrate 20 into contact with the etching solution. The etching process can be performed using the etching apparatus 40 described above. The glass substrate 20 in contact with the etching solution is gradually etched as shown in FIG. 5 (A). Since the copper layer 34 hardly reacts with acidic substances such as hydrofluoric acid contained in the etching solution, only the glass substrate 20 is finally etched in this etching process, as shown in FIG. 5 (B).

After the etching step, the protective film 36 is removed from the copper layer 34 (see FIG. 5C). After irradiating the protective film 36 with ultraviolet rays, it is possible to remove impurities such as an adhesive to the copper layer 34 by applying a physical force with almost no adhesion. Further, when the copper layer 34 is discolored or soiled by the etching treatment, it is preferable to appropriately perform a cleaning treatment or a gloss treatment. The gloss treatment is performed by bringing a known gloss liquid into contact with the copper layer 34. By performing the gloss treatment, the copper layer 34 can obtain the original gloss. Further, if necessary, the copper layer 34 may be subjected to surface treatment such as plating.

By performing the etching process, the glass substrate 20 can be removed with almost no force applied to the copper layer 34. Therefore, it is possible to manufacture the metal structure 10 while suppressing damage to the copper layer 34 filled in the through hole 22. Further, by coating the copper layer 34 with the protective film 36, it is possible to prevent the surface of the copper layer 34 from self-shrinking when the glass substrate 20 is removed.

From here on, other embodiments of the present invention will be described with reference to FIGS. 6 and 7. In this embodiment, a method for manufacturing the metal structure 101 having a plurality of plate-shaped fins 141 shown in FIG. 6A will be described. The metal structure 101 is a heat sink in which a plurality of fins 141 are provided on the base 12 at predetermined intervals. The fins 141 are ribbed protrusions and are provided along one end to the other end of the base 12.

From here, a method of manufacturing the metal structure 101 will be described. The description of the part of the manufacturing method that is substantially the same as the above-mentioned manufacturing method will be omitted. The method for manufacturing the metal structure 101 includes a metal layer forming step, a masking step, a metal layer removing step, and an etching step, similarly to the above-mentioned manufacturing method.

The metal layer forming step is a step of forming the copper layer 34 on the glass substrate 201. The glass substrate 201 is a single glass substrate corresponding to the metal structure 101, and has a groove portion 24 on one main surface. The groove portion 24 is a non-penetrating concave groove portion formed in the planned region where the fins 141 are formed. The groove portion 24 can be formed by combining a laser treatment and an etching treatment in the same manner as in the method for forming the through hole 22. When the concave groove portion 24 is formed, the focal length of the laser is adjusted so that the filament is formed only in the region where the groove portion 24 is to be formed so that the modified region is not formed in the entire area of the glass substrate 201 in the plate thickness direction. Just do it. By adjusting the filament formation position, it becomes possible to form an elongated concave groove 24 by the etching process.

In the metal layer forming step, as shown in FIG. 7A, a copper layer 34 is formed on the surface portion and the groove portion 24 of the glass substrate 201 by electroless plating. The copper layer 34 is plated so as to fill the groove 24. In the masking step, the copper layer 34 is covered with the protective film 36 on the main surface on the side where the groove 24 is formed. Subsequently, similarly to the above-described embodiment, the copper layer 34 on the main surface on which the groove 24 is not formed is removed in the metal layer removing step, and the glass substrate 201 is removed in the etching step (FIG. 7 (FIG. 7). B) and FIG. 7 (C)).

The metal structure 101 produced in this way is appropriately post-treated. In the present embodiment, the method of forming the rib-shaped fin has been described, but the shape of the convex portion of the metal structure according to the present invention is not limited to this. It is possible to form a convex portion having a desired shape by forming a convex portion having a desired shape by irradiating the glass substrate with a laser and etching the glass substrate. The convex portion may include, for example, a curved portion. Further, the metal structure according to the present invention can be used for applications other than heat sinks, and can be used, for example, for molds, semiconductor modules, and the like.

The description of the embodiments described above should be considered exemplary in all respects and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the claims.

10-Metallic structure 12-Base 14-Fin 20-Glass substrate 22-Through hole 24-Groove 30-Modified area 32-Filament 34-Copper layer 40-Etching device

Claims (3)

A method for manufacturing a metal structure including at least a metal base and a plurality of metal protrusions provided on the base.
A metal layer forming step of forming a metal layer on at least one surface of the glass substrate and a convex portion to be formed having holes, recesses or grooves formed on the surface of the glass substrate.
An etching step in which the glass substrate on which the metal layer is formed is melted by being brought into contact with an etching solution, and an etching step.
A method for manufacturing a metal structure including at least. The method for manufacturing a metal structure according to claim 1, further comprising a protective step for forming an etching-resistant layer having resistance to an etching solution in the metal layer before the etching step. The method for producing a metal structure according to claim 1 or 2, further comprising a pretreatment step of removing a part of a metal layer formed on the surface of the glass substrate before the etching step.

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