JP6093222B2 - Electroplating method and mask member used therefor - Google Patents

Description

  The present invention relates to an electroplating method and a mask member used therefor, and in particular, electroplating a predetermined portion on a metal circuit board of a metal-ceramic circuit board in which the metal circuit board is bonded to one surface of the ceramic board. The present invention relates to a method and a mask member used therefor.

  Conventionally, as a circuit board used in a power module for controlling a large current of an electric vehicle, a train, a machine tool, etc., a metal circuit board is joined to one surface of a ceramic substrate directly or via a brazing material. Ceramic circuit boards are used. A metal base plate is bonded to the other surface of the metal-ceramic circuit board, and a portion plated with nickel or a nickel alloy on the metal circuit plate bonded to one surface of the metal-ceramic circuit substrate is soldered. The semiconductor chip is fixed (for example, refer to Patent Documents 1 and 2).

Japanese Patent Laying-Open No. 2005-243767 (paragraph number 0012-0018)

  When plating a predetermined portion on a metal circuit board of a metal-ceramic circuit board, in electroplating, a mask member such as a silicon mask having a predetermined shape is pressed on the metal circuit board to mask the metal circuit board. However, in electroless plating, after applying a resist to a portion other than the portion to be plated on the entire surface of the metal-ceramic circuit board, plating on a portion where the resist is not applied, Since it is necessary to remove the resist, the process is complicated and costly due to the resist coating process and the resist peeling process. Moreover, in electroless plating, compared with electroplating, processing time is long, the amount of chemical | medical solutions to use is large, and cost starts. In particular, when a predetermined portion on a metal circuit board is subjected to electroless plating with a noble metal such as gold or silver, or a metal circuit with a large heat sink attached to a metal base plate joined to a metal-ceramic circuit board When electroless plating is performed on a predetermined portion on the plate, the effect of increasing the cost becomes large.

  However, when electroplating a predetermined part on the metal circuit board of the metal-ceramic circuit board, a mask member having an opening is disposed on the metal circuit board of the metal-ceramic circuit board in close contact with the mask member. It is necessary to pass a current between the electrode disposed in the plating tank and the metal circuit board while bringing the metal circuit board into contact with the plating solution in the plating tank through the opening of the metal-ceramic circuit board. It is not easy to supply power to the metal circuit board bonded to the ceramic substrate. If power is supplied locally to the power supply part of the metal circuit board using aluminum wire or the like, excessive current will be generated, and electrode traces and plating burns will occur in the power supply part. There is a problem.

  Therefore, in view of such a conventional problem, the present invention arranges a mask member having an opening on a metal circuit board of a metal-ceramic circuit board in close contact, and opens the mask member on the metal circuit board. It is an object of the present invention to provide an electroplating method and a mask member used therefor, which can prevent electrode traces and plating burns in a power feeding portion when electroplating a portion corresponding to the portion.

  As a result of diligent research to solve the above problems, the inventors of the present invention have provided a mask member having an opening on a metal circuit board of a metal-ceramic circuit board in which the metal circuit board is bonded to one surface of the ceramic board. After being placed in close contact, a current is passed between the electrode placed in the plating tank and the metal circuit board while the metal circuit board is in contact with the plating solution in the plating tank through the opening of the mask member. In the method of electroplating a portion corresponding to the opening of the mask member on the metal circuit board, the mask member is formed from a non-conductive member and a conductive member disposed inside the non-conductive member, The conductive member is exposed to the outside from the side surface between one pair of main surfaces facing each other and one main surface of the mask member, and the one main surface of the mask member is disposed in close contact with the metal circuit board. The metal circuit board By making contact, it is found that if an electric current is passed between the electrode in the plating tank and the metal circuit board through the conductive member, electrode traces and plating burn can be prevented in the power feeding portion. It came to be completed.

  That is, in the electroplating method according to the present invention, a mask member having an opening is placed in close contact with a metal circuit board of a metal-ceramic circuit board in which the metal circuit board is bonded to one surface of the ceramic board, and then the mask is formed. A mask member on the metal circuit board by passing a current between the electrode arranged in the plating tank and the metal circuit board while bringing the metal circuit board into contact with the plating solution in the plating tank through the opening of the member. In this method, the mask member is formed of a non-conductive member and a conductive member disposed inside the non-conductive member, and the conductive member is connected to each other of the mask member. The conductive member is brought into contact with the metal circuit board by exposing the side face between the pair of opposing main faces and the one main face to the outside and placing the one main face of the mask member in close contact with the metal circuit board. about More, wherein the current flow between the electrodes and the metal circuit plate in the plating tank via the conductive member.

  In this electroplating method, the non-conductive member is formed of the first and second non-conductive members, and the mask member is formed between the first non-conductive member and the second non-conductive member. Formed by sandwiched laminated structure, a projecting portion is formed integrally with a conductive member, and a through hole into which the projecting portion penetrates and fits is formed in the first non-conductive member, on the metal circuit board By placing the first non-conductive member in close contact and bringing the protruding portion of the conductive member into contact with the metal circuit plate, the electrode between the electrode in the plating tank and the metal circuit plate is interposed via the conductive member. It is preferable to pass an electric current through. In this case, the conductive member and the first and second nonconductive members are each formed in a substantially flat plate shape having the same planar shape, and the protruding portion is formed by protruding from one surface of the conductive member. preferable. Moreover, it is preferable to cover the inner surface of the opening of the conductive member corresponding to the opening of the mask member with at least one of the first and second non-conductive members, and the protrusion is formed by a plurality of protrusions. Is preferred. The first non-conductive member is preferably made of silicon rubber, the second non-conductive member is preferably made of glass epoxy, and the conductive member is preferably made of conductive rubber.

  Further, the electroplating mask member according to the present invention has a pair of main surfaces facing each other and a side surface between these main surfaces, and has an opening extending through and extending between these main surfaces. It consists of a conductive member and a conductive member disposed inside this non-conductive member, and this conductive member is exposed to the outside from the side surface and one main surface.

  In the electroplating mask member, the non-conductive member is composed of first and second non-conductive members, and the conductive member is sandwiched between the first non-conductive member and the second non-conductive member. Preferably, the first non-conductive member is formed with a projecting portion formed integrally with the conductive member, and a through hole into which the projecting portion penetrates and fits is formed. In this case, the conductive member and the first and second nonconductive members are each formed in a substantially flat plate shape having the same planar shape, and the protruding portion is formed to protrude from one surface of the conductive member. Is preferred. Moreover, it is preferable that the inner surface of the opening part of the conductive member corresponding to the opening part of the mask member is covered with at least one of the first and second non-conductive members, and the protrusions are formed from the plurality of protrusions. Preferably it is. The first non-conductive member is preferably made of silicon rubber, the second non-conductive member is preferably made of glass epoxy, and the conductive member is preferably made of conductive rubber.

  According to the present invention, when a mask member having an opening is placed in close contact with a metal circuit board of a metal-ceramic circuit board, and a portion corresponding to the opening of the mask member on the metal circuit board is electroplated. Furthermore, electrode traces and plating burns can be prevented in the power feeding section.

1 is a plan view of a metal-ceramic circuit board to be electroplated by an embodiment of an electroplating method according to the present invention. FIG. It is the IB-IB sectional view taken on the line of the metal-ceramic circuit board of FIG. 1A. It is a top view of the mask member used for embodiment of the electroplating method by this invention. It is the IIB-IIB sectional view taken on the line of the mask member of FIG. 2A. It is the IIC-IIC sectional view taken on the line of the mask member of FIG. 2A. It is a figure explaining embodiment of the electroplating method by this invention.

  Embodiments of an electroplating method according to the present invention and a mask member used therefor will be described below in detail with reference to the accompanying drawings.

  First, as shown in FIGS. 1A and 1B, one or more (four in the present embodiment) metal circuit board 12 is joined to one surface of the ceramic substrate 10, and the metal base plate 14 is joined to the other surface. A metal-ceramic circuit board in which one surface is bonded and the radiator 16 is bonded to the other surface of the metal base plate 14 is prepared. The metal circuit board 12 and the metal base board 14 are preferably made of aluminum or an aluminum alloy. The ceramic substrate 10 and the metal circuit board 12 and the metal base board 14 may be joined by a brazing material or may be directly joined. The radiator 16 is preferably made of aluminum or an aluminum alloy, and a multi-hole tube radiator can be used as the radiator 16.

  Further, a mask member used for electroplating the metal circuit board 12 of the metal-ceramic circuit board is produced. As shown in FIGS. 2A to 2C, the mask member 18 has one or a plurality (six in the present embodiment) of opening portions 18 a corresponding to the portion where the metal circuit board 12 is electroplated, and each of the mask members 18 is substantially the same. The plate-shaped conductive member 181 having the same planar shape, the first non-conductive member 182 and the second non-conductive member 183 are configured, and the conductive member 181 includes the first non-conductive member 182 and the first non-conductive member 182. It has a laminated structure that is sandwiched and bonded between two non-conductive members 183. 2A and 2C, the opening 181a of the conductive member 181 is formed larger than the opening 182a of the first non-conductive member 182 and the opening of the second non-conductive member 183. As shown in FIG. 2C, the inner surface of the opening 181a of the conductive member 181 protrudes from one surface of the first non-conductive member 182 and comes into contact with the second non-conductive member 183, and the conductive member. It is covered with a ridge wall 182b extending along the opening 181a of 181.

  In addition, the conductive member 181 is integrally formed with a plurality of (four in this embodiment) protruding portions 181b protruding from one surface thereof, and a through-hole through which the protruding portion 181b passes is fitted. When the first non-conductive member 182 is disposed in close contact with the metal circuit board 12, the protruding portion 181b of the conductive member 181 becomes the metal circuit board 12 (this embodiment). In the embodiment, each of the four projecting portions 181b comes into contact with the corresponding metal circuit board 12) of the four metal circuit boards 12. As the conductive member 181, a conductive member made of conductive rubber made conductive by adding carbon or metal particles to silicon rubber or the like can be used. Further, as the first non-conductive member 182, a non-conductive member made of relatively soft silicon rubber having good adhesion to the metal circuit board 12 can be used. Further, as the second non-conductive member 183, a non-conductive member made of glass epoxy having a relatively high rigidity capable of holding the conductive member 181 with the first non-conductive member 182 may be used. it can.

  As shown in FIG. 3, after the first non-conductive member 182 of the mask member 18 is disposed in close contact with the metal circuit board 12 of the metal-ceramic circuit board, the plating tank 20 containing the plating solution 22 is accommodated. The metal circuit board 12 is disposed on the side of the conductive member 181 of the mask member 18 while the portion corresponding to the opening 18a of the mask member 18 of the metal circuit board 12 is in contact with the plating solution 22. And the anode 24 disposed at the bottom of the plating tank 20 are electrically connected to cause a current to flow, the anode 24 and the metal circuit board 12 (as a cathode) are connected via the conductive member 181 of the mask member 18. An electric current flows between them, and electroplating can be performed on a portion corresponding to the opening 18 a of the mask member 18 on the metal circuit board 12.

  As described above, in the electroplating method according to the present invention, the power feeding portion to the metal circuit board 12 (the portion where the protruding portion 181b of the conductive member 181 contacts the metal circuit board 12) contacts the plating solution 22 in the plating tank 20. Therefore, it is possible to prevent plating from being deposited on the power feeding portion to the metal circuit board 12. In addition, it is possible to prevent an excess of current due to local power feeding and prevent electrode traces from being generated in the power feeding section.

  Hereinafter, examples of the electroplating method according to the present invention and mask members used therefor will be described in detail.

  First, by pouring molten aluminum into a mold in which a ceramic substrate 10 made of AlN is placed and cooling it, the metal circuit board 12 made of aluminum is directly joined to one surface of the ceramic substrate 10, and the other After one surface of the metal base plate 14 made of aluminum is directly bonded to the other surface, a multi-hole tubular radiator 16 is bonded to the other surface of the metal base plate 14 with an Al—Si brazing material. A metal-ceramic circuit board as shown in FIGS. 1A and 1B was produced.

  Further, a conductive member 181 having a thickness of 2 mm made of conductive rubber obtained by adding carbon to silicon rubber, a first non-conductive member 182 having a thickness of 2 mm made of silicon rubber, and a thickness of 2 mm made of glass epoxy resin. The second non-conductive member 183 was laminated to produce a mask member 18 as shown in FIGS. 2A to 2C. Note that the size of the opening 18a of the mask member 18 was 10 mm × 10 mm, and the size of the upper surface of the protrusion 181b of the conductive member 181 (the surface contacting the metal circuit board 12) was 5 mm × 5 mm.

Next, as shown in FIG. 3, after the first non-conductive member 182 of the mask member 18 is disposed in close contact with the metal circuit board 12 of the metal-ceramic circuit board, the plating containing the plating solution 22 is accommodated. The metal circuit board 12 is disposed on the tank 20 via the mask member 18, and the portion of the metal circuit board 12 corresponding to the opening 18 a of the mask member 18 is brought into contact with the plating solution 22, while the conductive member of the mask member 18. The portion corresponding to the opening 18a of the mask member 18 on the metal circuit board 12 was electroplated by electrically connecting the side surface of 181 and the anode 24 arranged at the bottom of the plating tank 20 to flow current. . In this electroplating, a Watt bath (containing 300 g / L nickel sulfate, 45 g / L nickel chloride and 30 / L boric acid, the balance being water) is used as the plating solution 22, and the temperature is 50 ° C., Ni plating was performed at a current density of 3 A / dm ² . As a result, good plating without plating unevenness, electrode traces and plating burn was obtained.

  As a comparative example, the size of the opening 181 a of the conductive member 181 is the same as the size of the opening 182 a of the first non-conductive member 182 and the opening of the second non-conductive member 183. The electroplating was performed in the same manner as in Example except that the mask member 18 (with the conductive member 181 exposed to the opening 18a) without the protruding wall 182b of the non-conductive member 182 was used. However, defects in appearance unevenness (electrode marks and plating burn) occurred on the surface of the Ni plating. In addition, plating is also deposited on the opening 181a (in contact with the plating solution 22) of the conductive member 181, and it is considered that a problem occurs in repeated use of the mask member 18.

DESCRIPTION OF SYMBOLS 10 Ceramic substrate 12 Metal circuit board 14 Metal base board 16 Radiator 18 Mask member 18a, 181a, 182a Opening 20 Plating tank 22 Plating solution 24 Anode (electrode)
181 Conductive member 181b Protruding portion 182 First nonconductive member 182b Projection wall 183 Second nonconductive member

Claims (18)

After a mask member having an opening is placed in close contact with the metal circuit board of the metal-ceramic circuit board having the metal circuit board bonded to one surface of the ceramic substrate, the inside of the plating tank is opened through the opening of the mask member. While the metal circuit board is in contact with the plating solution, a current is passed between the electrode arranged in the plating tank and the metal circuit board, and the portion corresponding to the opening of the mask member on the metal circuit board is electroplated In this method, the mask member is formed from a non-conductive member and a conductive member disposed inside the non-conductive member and having an inner surface of the opening corresponding to the opening of the mask member covered with the non-conductive member. The conductive member is exposed to the outside from the side surface between the pair of main surfaces facing each other and one main surface of the mask member, and the one main surface of the mask member is disposed in close contact with the metal circuit board. Conductive member By abutting the metal circuit plate, wherein the electric current between the electrode and the metal circuit plate in the plating tank via the conductive member, an electric plating method. The non-conductive member is formed of first and second non-conductive members, and the conductive member is sandwiched between the first non-conductive member and the second non-conductive member. A projecting portion is formed integrally with the conductive member, and a through-hole through which the projecting portion penetrates and fits is formed in the first non-conductive member, and is formed on the metal circuit board. An electrode in the plating tank and the metal circuit board are disposed through the conductive member by placing the non-conductive member of the first electrode in close contact and bringing the protruding portion of the conductive member into contact with the metal circuit board. The electroplating method according to claim 1, wherein a current is passed between the two. The conductive member and the first and second nonconductive members are each formed in a substantially flat plate shape having the same planar shape, and the protruding portion is formed by protruding from one surface of the conductive member. The electroplating method according to claim 2, wherein the electroplating method is characterized. The electroplating according to claim 3, wherein an inner surface of the opening of the conductive member corresponding to the opening of the mask member is covered with at least one of the first and second nonconductive members. Method. An inner surface of the opening of the conductive member corresponding to the opening of the mask member protrudes from one surface of the first non-conductive member and comes into contact with the second non-conductive member and the conductive The electroplating method according to claim 2, wherein the electroplating method covers the rib wall extending along the opening of the member. And forming the protrusion by a plurality of protrusions, electroplating method according to any one of claims 2 to 5. Said first non-conductive member is characterized in that it consists of silicone rubber, electroplating method according to any one of claims 2 to 6. Wherein the second non-conductive member, characterized in that it consists of a glass epoxy, electroplating method according to any one of claims 2 to 7. Wherein the conductive member is made of a conductive rubber, electroplating method according to any one of claims 1 to 8. Has a side surface between the pair of main surfaces and these main surfaces opposed to each other, in the electroplating mask member to have a opening therethrough extending between these main surfaces, the mask member is non-conductive member And a conductive member disposed inside the non-conductive member and having an inner surface of the opening corresponding to the opening of the mask member covered with the non-conductive member. A mask member for electroplating, which is exposed to the outside from a surface. The non-conductive member is formed of a laminated structure in which the non-conductive member is composed of first and second non-conductive members, and the conductive member is sandwiched between the first non-conductive member and the second non-conductive member. the protrusions on the conductive member are integrally formed, wherein the through hole the protrusion is fitted through is formed on the first non-conductive member, according to claim 10 Mask member for electroplating. The conductive member and the first and second nonconductive members are each formed in a flat plate shape having substantially the same planar shape, and the protruding portion is formed to protrude from one surface of the conductive member. The mask member for electroplating according to claim 11 , wherein: The inner surface of the opening portion of the conductive member corresponding to the opening portion of the mask member, characterized in that it is covered by at least one of the first and second non-conductive member, according to claim 12 Mask member for electroplating. An inner surface of the opening of the conductive member corresponding to the opening of the mask member protrudes from one surface of the first non-conductive member and abuts on the second non-conductive member and the conductive The mask member for electroplating according to any one of claims 11 to 13, wherein the mask member is covered with a protruding wall extending along the opening of the member. The protruding portion is characterized by comprising a plurality of protrusions, electroplating mask member according to any one of claims 11 to 14. Said first non-conductive member is characterized in that it consists of silicone rubber, electroplating mask member according to any one of claims 11 to 15. Wherein the second non-conductive member, characterized in that it consists of a glass epoxy, an electroplating mask member according to any one of claims 11 to 16. The conductive member, characterized in that is made of conductive rubber, electroplating mask member according to any one of claims 10 to 17.

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