JP2012151518A - Method of manufacturing circuit board and circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide many circuit boards out of a single ceramic substrate at a low cost.SOLUTION: A single large ceramic substrate 11 and a metal pattern plate 12 which has almost the same size as the former and is patterned are prepared. They are joined together as shown in FIG.1(c). The metal pattern plate 12 generally consists of a circuit pattern part 12a, at the center, in which the same pattern of two vertical columns×three horizontal rows (unit pattern) is arrayed, and a peripheral part 12b present around them. In any of the circuit pattern part 12a and the peripheral part 12b, individual patterns constituting them are connected with a connection part 13 which is smaller than them. The connection part 13 can be easily cut after division by using, for example, a cutter and a nipper. Likewise, a metal heatsink plate can be formed in pattern on the rear surface of the ceramic substrate 11.

Description

  The present invention relates to a method of manufacturing a circuit board having a structure in which a metal layer pattern is formed on a ceramic substrate, and a circuit board manufactured by the method.

  For example, a power semiconductor module (for example, an IGBT module) capable of high voltage and large current operation is used as an electric vehicle inverter. As such a semiconductor module, a semiconductor module is used in which a semiconductor chip is bonded to a circuit board having high electrical insulation and thermal conductivity and high mechanical strength. The circuit board is configured, for example, by forming a metal circuit board serving as wiring on an insulating ceramic substrate. The semiconductor chip is mounted on this circuit board, and the wiring in the semiconductor chip is electrically connected to the metal circuit board by solder, bonding wires or the like. As the material of the ceramic substrate, for example, silicon nitride is used, and as the material of the metal circuit board, for example, copper is used.

  At this time, by forming a large number of metal circuit board patterns on a single large ceramic substrate and then dividing the ceramic substrate, a large number of circuit substrates are obtained from a single ceramic substrate, and the manufacturing cost is thereby increased. Can be reduced.

  This circuit board can be manufactured, for example, by the manufacturing method shown in FIG. FIG. 7 is a process sectional view showing this manufacturing method. First, as shown in FIG. 7A, a copper plate 52 is brazed to a ceramic substrate 51 or bonded by a DBC (Direct Bonding Copper) method. Next, as shown in FIG. 7B, the copper plate is partially etched by a method such as wet etching to pattern the metal circuit plate 53. Further, as shown in FIG. 7C, a plating layer 54 is formed on the metal circuit board 53 for the purpose of improving solder wettability and preventing rust of the metal circuit board. Finally, as shown in FIG. 7 (d), the ceramic substrate 51 is divided to obtain a large number of circuit boards 50. This division can be easily performed by forming a scribe line on the ceramic substrate 51.

  Here, when the plating layer 54 is formed, the pattern of the metal circuit board 53 is formed, and if there is a separated pattern, it is difficult to energize all the patterns at the same time. Therefore, electroless plating that does not require energization is used to form the plating layer 54. Therefore, as the plating layer 54 formed here, a Ni—P layer that is easily electroless-plated, that is, a layer in which phosphorus (P) is added to nickel (Ni) is used.

  On the other hand, the Ni plating layer to which P is not added can easily form a uniform plating layer by performing electroplating, and the solder wettability is also better than that of the Ni-P plating layer. However, it is difficult to form this Ni layer (a layer to which P is not added) by electroless plating. Therefore, it is difficult to form this Ni plating layer on the metal circuit board 53 by the above manufacturing method.

  For this reason, for example, Patent Document 1 describes a manufacturing method in which electrolytic plating can be used in the manufacturing method shown in FIG. In this manufacturing method, a small pattern (tie bar) that electrically connects originally independent patterns is provided in the pattern formed in FIG. The tie bar has a length and a thickness that can be easily cut with a cutter. Therefore, this tie bar can be easily cut after the ceramic substrate 51 is divided (FIG. 7D). Therefore, electrolytic plating can be performed on a desired metal circuit board pattern by this manufacturing method.

  In the above example, the metal circuit board is described, but a metal heat radiating plate made of copper may be formed on the other surface of the ceramic substrate. The method of forming this is the same as in the case of the metal circuit board.

Japanese Patent Application Laid-Open No. 11-204921

  However, it has been difficult to sufficiently reduce the manufacturing cost even by the above manufacturing method.

  In the above manufacturing method, in order to obtain a large number of circuit boards at a time, it is necessary to first bond a large copper plate to a large ceramic substrate. As described above, this bonding is performed by brazing or the DBC method. However, at this time, the temperature becomes high, and the thermal expansion coefficients of the ceramic substrate (silicon nitride) and the copper plate are different. Therefore, after bonding, warping due to the difference in thermal expansion coefficient occurs, and this warping has an adverse effect on the subsequent patterning of the metal circuit board, and if the warping is large, substrate cracking or cracking may occur. is there.

  Therefore, there is a limit to the size of the ceramic substrate used, and it has been difficult to sufficiently reduce the manufacturing cost.

  The present invention has been made in view of such problems, and an object thereof is to provide an invention that solves the above problems.

In order to solve the above problems, the present invention has the following configurations.
The gist of the invention described in claim 1 is a method of manufacturing a circuit board, wherein a plurality of circuit boards each having a patterned metal layer formed on a ceramic substrate are manufactured from a single ceramic substrate, A metal pattern plate manufacturing process for manufacturing a metal pattern plate having a circuit pattern portion in which a plurality of patterns of the metal layer are arranged, and independent portions connected by a coupling portion, and the one piece A bonding step of bonding the metal pattern plate on the ceramic substrate, a dividing step of dividing the ceramic substrate to which the metal pattern plate is bonded, and a joint portion of the metal pattern plate bonded on the ceramic substrate. anda coupling portion removing step of removing, in said metal pattern plate manufacturing process, different patterns with the sequence is made at the same pitch Two types of metal pattern plates are manufactured, and in the joining step, the two types of metal pattern plates are aligned so that circuit pattern portions in the two types of metal pattern plates correspond to each other, and the phase of the ceramic substrate is adjusted. It exists in the manufacturing method of the circuit board characterized by joining to a different surface .
The gist of the invention described in claim 2 is characterized in that a plating step for forming a plating layer on the surface of the metal pattern plate is performed after the joining step and before the dividing step and the bonding portion removing step. A circuit board manufacturing method according to claim 1.
The gist of the invention described in claim 3 resides in the method for manufacturing a circuit board according to claim 2, wherein an electrolytic plating method is used in the plating step.
The gist of the invention described in claim 4 is that, in the joining step, brazing is used for joining the one ceramic substrate and the metal pattern plate. The method of manufacturing a circuit board according to Item 1 exists.
The gist of the invention described in claim 5 is that, in the joining step, a DBC (Direct Bonding Copper) method is used for joining the one ceramic substrate and the metal pattern plate. 3. The method for producing a circuit board according to any one of items 3 to 3.
The gist of the invention described in claim 6 is that the metal pattern plate includes a peripheral portion supporting the circuit pattern portion around the circuit pattern portion, and the circuit pattern portion and the peripheral portion are connected to each other. The circuit board manufacturing method according to any one of claims 1 to 5, wherein the circuit boards are coupled by a portion.
The gist of the invention described in claim 7 is that the metal pattern plate has a joint portion between the joint portion and an independent portion in the metal pattern plate, and the independent portion in the metal pattern plate is opposite to the joint portion side. The circuit board manufacturing method according to any one of claims 1 to 6, further comprising a shape drawn to the side.
The gist of the invention described in claim 8 is that, in the metal pattern plate, the thickness of the joint portion is smaller than a part of the metal pattern plate adjacent to the joint portion on the ceramic substrate side to be joined. A circuit board manufacturing method according to any one of claims 1 to 7, characterized in that:
The gist of the invention described in claim 9 is that the press working is used in the metal pattern plate manufacturing process. The method for manufacturing a circuit board according to any one of claims 1 to 8, Exist.
The gist of the invention described in claim 10 resides in the method for manufacturing a circuit board according to any one of claims 1 to 9, wherein the metal pattern plate is formed of copper or a copper alloy. .
The gist of the invention described in claim 11 resides in a circuit board manufactured by the method for manufacturing a circuit board described in any one of claims 1 to 10 .

  Since the present invention is configured as described above, a large number of circuit boards can be obtained at low cost from a single ceramic substrate.

It is a figure which shows each process of the manufacturing method of the circuit board which concerns on embodiment of this invention. It is a figure which shows the structure of the metal pattern board used in the manufacturing method of the circuit board which concerns on embodiment of this invention. It is a figure which shows the pattern of the metal circuit board in the circuit board manufactured using the metal pattern board shown in FIG. It is a figure which shows the fracture | rupture location in the division | segmentation process of the manufacturing method of the circuit board which concerns on embodiment of this invention. It is a figure which shows an example of a structure of the coupling | bond part vicinity in the metal pattern board used in the manufacturing method of the circuit board which concerns on embodiment of this invention. It is sectional drawing which shows another example of the structure of the connection part vicinity in the metal pattern board used in the manufacturing method of the circuit board which concerns on embodiment of this invention. It is a figure which shows an example of the manufacturing method of the conventional circuit board.

  The present invention will be described below with reference to specific embodiments. However, the present invention is not limited to these embodiments.

  In this manufacturing method, a large number of circuit boards are produced from one large ceramic substrate. FIG. 1 is a diagram showing this manufacturing method. The circuit board manufactured here has a structure in which a patterned metal layer (here, a metal circuit board) is formed on a ceramic substrate. In addition, in FIG. 1, (a)-(d) is a perspective view of the manufactured form, (e), (f) is a top view.

  First, as shown in FIG. 1 (a), one large ceramic substrate 11 and as shown in FIG. 1 (b), the patterned metal pattern plate 12 is almost the same size as this. Is prepared. Thereafter, they are joined as shown in FIG. 1C (joining step). This joining is performed, for example, at a temperature of 700 ° C. or higher by brazing or DBC (Direct Bonding Copper) method.

  The ceramic substrate 11 used here is made of, for example, silicon nitride ceramics as a ceramic material having high insulation, thermal conductivity, and mechanical strength. The size is, for example, about 10 cm square because a large number of circuit boards are divided and produced from here. The thickness is about 0.32 mm.

  FIG. 2 is a plan view of the metal pattern plate 12 when viewed from the upper side in FIG. The metal pattern plate 12 is made of copper or a copper alloy, which is a material for forming a metal circuit board, and has a thickness of about 0.1 to 3 mm, for example.

  The metal pattern plate 12 is roughly divided into a circuit pattern portion 12a in which the same pattern (unit pattern) of 2 vertical columns × 3 horizontal rows in the center is arranged, and a peripheral portion 12b in the periphery thereof. In both the circuit pattern portion 12a and the peripheral portion 12b, individual patterns (both are rectangular patterns in FIG. 2) are connected by a connecting portion 13 smaller than these.

  A total of six identical patterns of 2 × 3 in the circuit pattern portion 12a correspond to the pattern of the metal circuit board (metal layer) 16 in the circuit board to be manufactured. However, the pattern of the metal circuit board finally obtained here is composed of two electrically independent locations A and B as shown in FIG. Accordingly, the metal pattern plate 12 has a configuration in which A and B are coupled by the coupling portion 13, and the coupling portion 13 is added to the original pattern of the metal circuit board. The width of the connecting portion 13 is preferably about 1 mm because strength for fixing each pattern can be ensured and work at the time of cutting described later is facilitated.

  The peripheral portion 12b is composed of a plurality of rectangular patterns. Similarly, the respective rectangular patterns are coupled by the coupling portion 13. In addition, the peripheral portion 12b and the circuit pattern portion 12a are also coupled by the coupling portion 13. Therefore, the circuit pattern portion 12a is supported by the peripheral portion 12b.

  Therefore, in the metal pattern board 12, it is couple | bonded by the part (A and B in FIG. 3) which should be made into an independent shape after that originally an independent place, and the other location coupling | bond part 13 in the metal pattern board 12. FIG. It has a different shape. Thereby, each part in the metal pattern board 12 is integrated mechanically and electrically through the circuit pattern part 12a and the peripheral part 12b.

  In addition, said pattern is manufactured by a metal pattern board manufacturing process. Here, for example, it can be formed by performing wet etching on a single copper plate having a desired thickness. Or it can create by pressing a copper plate.

  After the metal pattern plate 12 is bonded to the ceramic substrate 11 as shown in FIG. 1C (bonding step), the metal pattern is immersed in an electrolytic plating solution as shown in FIG. The plate 12 is energized. Thereby, the plating layer 14 is formed on the entire surface of the metal pattern plate 12 (plating process). Here, as the plating layer, a layer made of Ni can be formed by electrolytic plating. At this time, since the metal pattern plate 12 is electrically integrated, the plating layer 14 can be formed on the entire surface.

  Thereafter, by dividing the ceramic substrate 11 in the direction indicated by the broken line in FIG. 4 in the metal pattern plate 12, six divided units 15 whose top view is shown in FIG. 1 (e) are obtained (dividing step). . This operation can be performed particularly easily by providing a scribe line corresponding to a portion indicated by a broken line in FIG. 4 of the ceramic substrate 11.

  During this division, some of all the coupling parts 13 are destroyed. However, as shown in FIG. 1 (e), other parts, particularly the coupling parts 13 in one circuit board, The form is maintained. This joint part 13 can be easily cut using a cutter or a nipper after the division (joint part removing step). Thereby, it is possible to obtain the circuit substrate 10 in the form of FIG. 1F in which the metal circuit board 16 having the plating layer 14 formed on the surface thereof is formed on the ceramic substrate 11. Accordingly, six circuit boards 10 having a desired shape can be obtained.

  In the above example, the bonding portion removing process is performed after the dividing step. However, the dividing step may be performed after the bonding portion removing process.

  When the metal pattern plate 12 is formed of a material that can be easily soldered, the plating step (FIG. 1D) is not necessary. In the above example, the plating step is performed immediately after the joining step, but may be performed after the joining step and before the dividing step and the bonding portion removing step.

  In the manufacturing method described above, the case where the metal circuit board 16 is formed on the ceramic substrate 11 has been described. Similarly, a patterned metal heat dissipation plate can be formed on the back surface of the ceramic substrate 11. In this case, in the metal pattern plate manufacturing process, two types of metal pattern plates arranged at the same pitch are manufactured. The unit pattern of the circuit pattern portion on one side (first metal pattern plate) is a pattern corresponding to the metal circuit plate, and the unit pattern of the circuit pattern portion on the other side (second metal pattern plate) is a metal heat sink. The corresponding pattern. At this time, the pitch of these arrays is the same. Thereafter, in the joining step, the two types of metal pattern plates are aligned so that the circuit pattern portions of these metal pattern plates correspond to each other, and are joined to different surfaces (front surface and back surface) of the ceramic substrate 11. . Thereafter, the plating process (FIG. 1D) and subsequent steps are performed. However, the plating process in this case may be performed independently for each surface, or may be performed simultaneously. Or you may perform only about one side.

  In the above manufacturing method, in the joining step (FIG. 1C), the metal pattern plate 12 and the ceramic substrate 11 are firmly joined at a high temperature, for example, 700 ° C. or higher, by brazing or the DBC method. Thereafter, they are cooled to room temperature. At that time, stress is generated due to the difference in thermal expansion coefficient between the ceramic substrate (silicon nitride) and copper, which causes warpage.

  However, since the metal pattern plate 12 to be joined here is patterned as shown in FIG. 2, stress concentrates on each part in this pattern, for example, each rectangle in A and B in FIG. 3 and the peripheral part 12b. It is a pattern. The size of each part is smaller than the overall size of the ceramic substrate 11 as shown in FIG. Therefore, the warp in each part is not a problem. Further, although there is an influence of stress between these parts, warping in the ceramic substrate 11 and the like is alleviated at this point by the deformation of the small and thin coupling part 13 according to this stress. Accordingly, the amount of warpage in the form (FIG. 1C) after the metal pattern plate 12 is joined is reduced. This effect is remarkable when the ceramic substrate 11 and the metal pattern plate 12 are large, and when the number of parts in the metal pattern plate 12 is large. Therefore, a great effect can be obtained particularly when a large number of circuit boards 10 are manufactured from one large ceramic substrate 11.

  On the other hand, in the manufacturing method described in Patent Document 1, first, an unpatterned copper plate having the same shape as the ceramic substrate is prepared, and this is bonded to the ceramic substrate, and then patterned into the shape of FIG. For this reason, after cooling after this joining, especially when the ceramic substrate is large, the influence of the warp becomes large.

  Furthermore, in the manufacturing method described in Patent Document 1, first, the copper plate is processed into the same shape (for example, a rectangle) as the ceramic substrate, and then patterned into the shape of FIG. I need it. On the other hand, in the manufacturing method of this embodiment, since only one processing before joining is required, the manufacturing cost can be reduced. In particular, when press working is used for this processing, patterning into a desired size and the shape of FIG. 2 can be easily performed once.

  Further, in the plating step (FIG. 1 (d)), the metal pattern plate 12 has a structure in which the metal pattern plate 12 is integrated electrically and mechanically, so that electrolytic plating can be easily applied. Therefore, a Ni layer to which P is not added can be formed on the surface of the metal circuit board by electrolytic plating. Therefore, it is possible to form a plating layer that is inexpensive and easy to solder. However, electroless plating can also be applied.

  Therefore, a large number of circuit boards can be obtained from a single ceramic substrate at a low cost.

  In the metal pattern plate 12, it is preferable that the shape around the coupling portion 13 be a shape that makes it particularly easy to remove the coupling portion 13 from the configuration shown in FIG.

  FIG. 5 is an enlarged plan view of the periphery of the coupling portion 13 in an example of the shape for this purpose. In this shape, two circuit patterns (a part of the metal pattern plate 12) 17 and 18 are coupled by the coupling portion 13. It is assumed that the circuit patterns 17 and 18 are electrically separated from each other as a configuration of the original metal circuit board. Here, if burrs remain when the connecting portion 13 is removed with a cutter or the like after the division, these burrs may cause an electrical short circuit. In this example, in order to prevent this short circuit, the connection part between the circuit patterns 17 and 18 and the coupling part 13 is drawn into the opposite side of the coupling part 13 by a distance d. Thereby, the short circuit between the circuit patterns 17 and 18 by the burr | flash after a cutting | disconnection can be suppressed.

  FIG. 6 is a sectional view of the shape around the coupling portion 13 in another example. In this example, a coupling portion 13 is provided between the circuit patterns 19 and 20. As described above, these are formed integrally with the copper plate, but the thickness in the circuit patterns 19 and 20 is t1, whereas in the coupling portion 13, t2 (t2 <t1). That is, the thickness of the connecting portion 13 is reduced. Thereby, it is possible to easily remove the connecting portion 13 after the division.

  In particular, as shown in FIG. 6, it is preferable that the thickness of the coupling portion 13 is made thinner than the locations 19 and 20 in the adjacent metal pattern plate 12 on the ceramic substrate 11 side. In this case, when the metal pattern plate 12 is joined by brazing, since the brazing material is suppressed from adhering to the lower surface (surface to be joined) of the joining portion 13, removal of the joining portion 13 after the division is performed. Is particularly easy. Even in the case of bonding by the DBC method, since the bonding portion 13 itself is not bonded to the ceramic substrate 11, the removal thereof is similarly facilitated.

  The shape of FIG. 6 can be easily formed by, for example, selectively wet-etching the lower surface of the coupling portion 13 after patterning the metal pattern plate 12 (FIG. 1B).

  In addition, it is more preferable to use the planar shape shown in FIG. 5 and the cross-sectional shape shown in FIG. 6 at the same time. In this case, the removal of the coupling portion 13 is particularly easy, and a short circuit between circuit patterns after removal can be suppressed.

  By applying these structures particularly to the coupling portion in the circuit pattern portion 12a, a short circuit between circuit patterns can be suppressed.

  In addition, although the structure of the metal pattern board 12 shall consist of the circuit pattern part 12a and the peripheral part 12b as FIG. 2 shows, it is not restricted to this. The peripheral portion 12b is not provided, and all may be a circuit pattern portion 12a, that is, a repeated pattern of a metal circuit board pattern. In this case, more circuit boards can be obtained simultaneously.

  In the example of FIG. 2, the circuit pattern portion 12a is a repeated pattern of the circuit pattern shown in FIG. 3, but the present invention is not limited to this. If the configuration can be easily divided later, different circuit patterns can be arranged and different types of circuit boards can be manufactured at the same time. In this case, in order to make the division particularly easy, the size (length and width) is preferably the same. Further, the arrangement may be a one-dimensional arrangement instead of a two-dimensional arrangement.

DESCRIPTION OF SYMBOLS 10, 50 Circuit board 11, 51 Ceramic substrate 12 Metal pattern board 12a Circuit pattern part 12b Peripheral part 13 Joint part 14, 54 Plating layer 15 Dividing unit 16, 53 Metal circuit board 17, 18, 19, 20 Circuit pattern (metal pattern) Part of the board)
52 Copper plate

Claims (11)

A method of manufacturing a circuit board, comprising manufacturing a plurality of circuit boards each having a patterned metal layer formed on a ceramic substrate from a single ceramic substrate,
A metal pattern plate manufacturing process for manufacturing a metal pattern plate comprising a circuit pattern portion in which a plurality of patterns of the metal layer are arranged, and being connected and integrated by a connecting portion between independent locations;
A bonding step of bonding the metal pattern plate on the one ceramic substrate;
A dividing step of dividing the ceramic substrate to which the metal pattern plate is bonded;
A bonding portion removing step for removing the bonding portion of the metal pattern plate bonded on the ceramic substrate;
Equipped with,
In the metal pattern plate manufacturing process, two kinds of metal pattern plates having different patterns are manufactured while the arrangement is made at the same pitch,
In the bonding step, the two types of metal pattern plates are aligned so that the circuit pattern portions in the two types of metal pattern plates correspond, and are bonded to different surfaces of the ceramic substrate.
A method of manufacturing a circuit board.   The method of manufacturing a circuit board according to claim 1, wherein a plating step of forming a plating layer on the surface of the metal pattern plate is performed after the joining step and before the dividing step and the bonding portion removing step. .   The method for manufacturing a circuit board according to claim 2, wherein an electrolytic plating method is used in the plating step.   4. The circuit board manufacturing method according to claim 1, wherein brazing is used for joining the one ceramic substrate and the metal pattern plate in the joining step. 5.   4. The circuit according to claim 1, wherein a DBC (Direct Bonding Copper) method is used for joining the one ceramic substrate and the metal pattern plate in the joining step. 5. A method for manufacturing a substrate. The metal pattern plate is
The peripheral portion supporting the circuit pattern portion is provided around the circuit pattern portion, and the circuit pattern portion and the peripheral portion are coupled by the coupling portion. 6. The method for manufacturing a circuit board according to any one of 5 to 5. The metal pattern plate is
The joint part of the said connection part and the independent location in the said metal pattern board WHEREIN: The independent location in the said metal pattern board comprises the shape pulled in on the opposite side to the said connection part side. The method for manufacturing a circuit board according to claim 1. In the metal pattern plate,
The thickness of the said joint part is smaller than a part of metal pattern board adjacent to the said joint part in the said ceramic substrate side joined, The any one of Claim 1-7 characterized by the above-mentioned. A method for manufacturing a circuit board according to claim 1.   The method for manufacturing a circuit board according to any one of claims 1 to 8, wherein press working is used in the metal pattern plate manufacturing process.   The method for manufacturing a circuit board according to claim 1, wherein the metal pattern plate is made of copper or a copper alloy. The circuit board manufactured by the manufacturing method of the circuit board of any one of Claim 1- Claim 10 .