JP5102497B2 - Method for manufacturing metal-ceramic bonded circuit board - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention can prevent a metal element / chip component from being displaced from a predetermined position when soldering a semiconductor element / chip component mounted on the aluminum / ceramic bonding substrate, in particular, a method for manufacturing the same. The present invention relates to a metal ceramics bonded circuit board and a manufacturing method thereof.

  In Patent Document 1, a circuit board provided with a conductive layer having a predetermined circuit pattern, a heat sink joined to the circuit board by solder, a semiconductor element joined to the heat sink by solder, and each of these parts A semiconductor device including a bonding wire that is electrically connected is disclosed. The main surface of the heat sink to which the semiconductor element is fixed has a solderable region and a metal region that repels solder, and a region where the chip of the heat sink is not mounted is a region that repels solder. As a result, it is disclosed that the flow of the mount solder is prevented, there is no variation, the solder thickness becomes uniform, and the TFT level is improved.

In Patent Document 2, a conductive thin film is formed on the surface of a circuit board, and when the conductive thin film melts a bonding material around the element mounting region for the purpose of bonding, an excess of the melt flows. It is disclosed to have a partition groove that can be stored.
JP-A-8-148647 JP 2004-39988 A

  The production of a metal region that repels solder or a metal region that can be soldered described in Patent Document 1 needs to be formed by, for example, etching or attaching such metal or masking. Moreover, in patent document 2, since the process which removes a conductor with a laser and exposes a ceramic substrate is performed, the effect cannot be obtained unless the thickness of the conductor is thin or the ceramic substrate is exposed.

  An object of the present invention is to prevent a solder flow when a semiconductor or a chip component is mounted with solder in a metal-ceramic bonded circuit board on which a relatively thick circuit metal plate is bonded, for example, on which a power semiconductor is mounted. An object of the present invention is to provide a method capable of easily producing a metal-ceramic bonded circuit board for preventing displacement of chip parts in a short time.

The method for manufacturing a metal ceramic bonded circuit board according to the present invention includes bonding a ceramic substrate and an aluminum plate by any one of a brazing method, a direct bonding method, and a molten metal bonding method, and processing the bonded aluminum plate. After forming an aluminum circuit board on the substrate, one of a nickel plating layer , a nickel alloy plating layer, and a copper plating layer that can be soldered to the surface of the aluminum circuit board is formed by electroplating or electroless plating. A portion where the plating layer is removed around the portion of the layer where the semiconductor element or the chip component is soldered and the aluminum circuit board is exposed is irradiated with a laser to form a portion where the solder is not wetted.

Irradiation of the laser, YAG, characterized der Rukoto by laser irradiation apparatus for laser marker using either YVO _4, CO _2.

The aluminum circuit board, wherein the aluminum or aluminum alloy der Rukoto thickness 0.1 to 1.0 mm.

  According to the present invention, for example, in an aluminum ceramic bonded circuit board on which a power semiconductor is mounted and a relatively thick circuit metal plate is bonded, solder flow when mounting a semiconductor or a chip component with solder is prevented. It is possible to provide a metal-ceramic bonding circuit board for preventing displacement of chip components and a method for easily producing the same in a short time.

  Further, in the present invention, in order to produce a portion where the solder does not get wet, it is only necessary to irradiate a laser. That is, it is not necessary to form a metal or resin (solder resist or the like) that does not wet solder, or to perform masking and etching, thereby reducing the cost. Further, since processing is performed with a laser, only a fine portion can be formed where the solder is not wetted, so that the circuit board can be reduced in size. Moreover, it can be used even under relatively high soldering temperature conditions such as high-temperature solder and Pb-less solder.

  Furthermore, since only part of the surface of the aluminum circuit board is processed by laser irradiation, two or more unsoldered parts can be formed on one circuit board (island). That is, for example, a plurality of semiconductor chips can be mounted on one island, and the circuit design can have a high degree of freedom.

  The present invention will be described below with reference to the drawings.

  An aluminum ceramic bonded circuit board as an example of the present invention heats and bonds an aluminum circuit board 3 as a circuit metal plate to a ceramic board 1 via a brazing material 2 and then forms a circuit pattern as necessary. Masking, exposure, etching, and peeling of the masking member were performed to form a circuit pattern. A solderable plating layer 4 is applied to the surface of the aluminum circuit board 3. As the plating layer 4 having good solderability, a nickel plating layer, a nickel alloy plating layer, copper, gold, silver, or a tin plating layer is preferable. These plating layers can be formed by electroplating or electroless plating.

  Thereafter, a laser is irradiated around the plating layer of the portion 5 on which the semiconductor element or chip portion (capacitor, resistor, etc.) is mounted to form a portion 6 where the solder does not get wet. Since the aluminum surface is exposed to the laser irradiated portion by the laser irradiation, or the aluminum is exposed and the surface is oxidized to deteriorate the solder wettability or the aluminum surface is not exposed, the structure of the plating layer 4 It is considered that the solder wettability is deteriorated due to the change of the solder or oxidation. Further, as shown in the figure, two or more portions where solder does not wet may be formed on one aluminum plate 3 (island).

  The bonding of the ceramic substrate 1 and the aluminum circuit board 3 can be any of a direct bonding method, a bonding method using an adhesive, and a molten metal bonding method, in addition to the brazing method. Moreover, an aluminum circuit board may be joined to both surfaces, and a heat sink may be joined to the opposite surface where the aluminum circuit board is joined.

  Further, the portion where the solder does not get wet is formed at a position lower than the plated layer 4 on the aluminum circuit board 3 in order to form the plated surface by laser irradiation.

  The ceramic substrate 1 is typically a ceramic substrate having a composition mainly composed of alumina, aluminum nitride, and silicon nitride, which is used for an aluminum ceramic substrate for a power module, and these are preferably used.

  The brazing material 2 is preferably an Al-based brazing material, for example, an Al—Si based brazing material, for joining aluminum circuit boards.

  The aluminum circuit board 3 is preferably made of aluminum or aluminum alloy (Al-Si alloy or the like) having a purity of 99.5% or more. The thickness is preferably 0.1 to 1.0 mm, more preferably 0.15 to 0.6 mm, and still more preferably about 0.25 to 0.5 mm. This is because, in the case of mounting a power semiconductor or the like, a thickness that is somewhat thicker than electric resistance or the like is required.

As a laser irradiation apparatus, there is a laser using YAG, YVO ₄ , or Co ₂ , but any apparatus may be used. For example, it is preferable for a laser marker because it is easy to irradiate a laser on a thin pattern along a predetermined shape by a program. At the same time, it is possible to mark the product name, etc. Also, if a workpiece is placed on the device, it is automatically processed by a program, so it can be processed easily and in a short time (several to several tens of seconds / sheet). it can. Laser processing is preferably performed so that the plating layer is removed and the aluminum surface is exposed (about 0.5 to 20 μm in depth from the plating surface).

  The thickness of the plating is preferably about 0.5 to 10 μm. If the thickness is too thin, the solderability is poor. If the thickness is too thick, the laser irradiation time must be increased for processing. More preferably, it is 1-6 micrometers.

  An aluminum nitride substrate having a length of 50 mm, a width of 50 mm, and a thickness of 0.6 mm is prepared as a ceramic substrate, and a 99.9% aluminum plate having a thickness of 0.5 mm is formed on almost both surfaces of the aluminum nitride substrate by a molten metal bonding method. did. Next, an etching resist formed in a circuit pattern shape was applied to the surface of the aluminum plate, and UV cured and masked. Thereafter, an unnecessary aluminum plate was removed with an iron chloride solution to obtain an aluminum circuit board.

  Thereafter, a nickel-phosphorous plating layer was applied to 3 μm over the entire surface of the aluminum circuit board by electroless plating.

  Next, assuming a portion on which a square semiconductor chip having a side of 10 mm was mounted, the periphery was programmed to irradiate a laser beam with a width of 0.5 mm with a YVO4 laser device (manufactured by KEYENCE). After that, as a result of laser irradiation processing, discoloration was observed in the irradiated part. Moreover, the laser-processed part was a position lower than the plating layer surface.

  Next, when the aluminum ceramic bonded circuit board after laser processing was dipped in a solder bath (230 ° C.) in which eutectic solder was melted for 30 seconds, only the laser processed portion did not get wet.

  A sample was prepared by the method described in Example 1 except that the plating was nickel electroplating, and the same evaluation was performed. As in Example 1, the solder was not wetted only in the laser processed part.

  A sample was prepared by the method described in Example 1 except that the aluminum plate and the aluminum nitride substrate were bonded via an Al—Si brazing material, and the same evaluation was performed. Solder did not get wet only in the processed part.

  A sample was prepared by the method described in Example 3 except that the plating was nickel electroplating, and the same evaluation was performed. As in Example 1, the solder did not get wet only in the laser processed part.

  A eutectic solder foil having a thickness of 0.1 mm with a side of 10 mm is placed on the semiconductor mounting portion of the samples of Examples 1 to 4, and a 10 mm square semiconductor chip (soldered surface is metallized) thereon. After being mounted and heated to 250 ° C., it was cooled and joined. At this time, the solder did not flow out beyond the laser processing portion, the semiconductor chip was soldered at a predetermined position, and there was no positional deviation.

  (Comparative Example 1)

  An aluminum nitride substrate having a length of 50 mm, a width of 50 mm, and a thickness of 0.6 mm is prepared as a ceramic substrate, and a 0.2 mm-thick copper plate is placed on almost the entire surface of both sides of the aluminum nitride substrate with an Ag-Cu-Ti brazing material. A sample was prepared by the method described in Example 1 except that it was joined, and the same evaluation was performed.

  Discoloration was observed in the laser-irradiated part. In the solder wetting evaluation under the same conditions as in Example 1, the solder was also wetted on the laser-irradiated portion.

It is a perspective view of the metal ceramic substrate obtained by the method of this invention. It is the sectional view on the AA line of the metal ceramic substrate shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic substrate 2 Brazing material 3 Aluminum circuit board 4 Plating layer 5 The part which solders a semiconductor or a chip component 6 The part which does not wet solder

Claims (3)

After the aluminum circuit board is formed on the ceramic substrate by bonding the ceramic substrate and the aluminum plate by any one of the brazing method, the direct bonding method, and the molten metal bonding method, and processing the bonded aluminum plate , the aluminum circuit A portion where one of a nickel plating layer , a nickel alloy plating layer, and a copper plating layer that can be soldered to the surface of the plate is formed by electroplating or electroless plating , and a semiconductor element or chip component of the plating layer is soldered A method for producing a metal-ceramic bonding circuit board, comprising forming a portion where solder is not wetted by irradiating a laser under the condition that the plating layer is removed around the aluminum substrate and the aluminum circuit board is exposed . The irradiation of the laser, YAG, YVO _4, claim 1 metal ceramic bonding circuit manufacturing method of the substrate, wherein the der Rukoto by laser irradiation apparatus for laser marker with either CO _2. The aluminum circuit board, according to claim 1 or 2 metal ceramic bonding circuit manufacturing method of the substrate, wherein the aluminum or aluminum alloy der Rukoto thickness 0.1 to 1.0 mm.

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