JP2010238762A - Method of forming through hole, and multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a through hole by which adhesive force of plating provided on an inner side of the through hole is improved. <P>SOLUTION: The method of forming a through hole 16 includes: a process for forming a multilayer structure by forming through hole conduction patterns 11, 12 on a portion for forming the through hole of layers which are electrically conducted, and forming plating reinforcing patterns 17 on the portion for forming the through hole of layers which do not need to be electrically conducted in a lamination step of a multilayer printed wiring board 10; a process for forming the through hole 13 on the portion for forming the through hole; and a process for plating the inner side of the through hole. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for forming a through hole and a multilayer printed wiring board with improved adhesion of plating applied in a through hole for the through hole.

  In multilayer printed wiring boards, a method has been conventionally used to ensure electrical continuity between layers through holes by forming through holes for through holes at pattern locations that require continuity between layers and plating the inside of the through holes. It was. For example, as shown in FIG. 3A, when the outermost layers of the four-layer printed wiring board 10 are electrically connected to each other, the through-hole conduction pattern 11 is previously formed at a place where a through-hole is to be formed. 12 is formed. As shown in FIG. 3B, a through-hole 13 is drilled at a location where the through-hole conduction patterns 11 and 12 are formed so as to penetrate the conduction patterns 11 and 12 and the substrate 15. Thereafter, as shown in FIG. 3C, plating 14 is applied to the inside of the through hole 13, whereby the conductive patterns 11 and 12 and the plating 14 are metal-bonded to form a through hole 16. Through holes 16, the conductive patterns 11 and 12 are electrically connected to each other so that the outermost layers can be electrically connected to each other.

  As the shape of the through hole 16, in addition to the case where the circular through hole 13 is formed, as shown in FIG. 4A, a long through hole formed long in one direction, or FIG. As shown in FIG. 4, there are various shapes of through holes such as a through hole formed in a shape close to a square.

As an example of forming the through hole as described above, for example, Patent Literature 1 has already been proposed. In addition, the present applicant has already proposed Patent Document 2 as a method for forming a long through hole as shown in FIG.
JP 2008-113022 A JP 2007-0985502 A

  By the way, when forming a through hole as shown in FIG. 3 (c), due to the generation of gas from the substrate material, etc., as shown by the arrow in FIG. May join. In this case, since the plating 14 is bonded only at the through-hole conduction patterns 11 and 12, there is a possibility that the vicinity of the center of the wall surface of the through-hole swells, and further, as shown in FIG. Thus, corner cracks may occur due to the concentration of pressure at the plating joints indicated by the broken-line circles. This may eventually lead to peeling of the plating.

  Such a problem of a decrease in the adhesion strength of the plating is likely to occur in a through hole having a linear portion (a range indicated by an arrow) as shown in FIGS. 4A and 4B. Electrical connection may become unstable.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for forming a through hole in which the adhesion of plating applied to the inside is improved, and a multilayer printed wiring board in which the through hole is formed. It is.

  According to a first aspect of the present invention, in the step of laminating a multilayer printed wiring board, a layer for through-hole conduction is formed at a location where a through-hole is to be formed in a layer to be electrically conducted, and the layer need not be electrically conducted. A procedure for forming a multilayer structure by forming a plating strengthening pattern at a through-hole formation planned location, a procedure for forming a through-hole at the through-hole formation planned location, and a procedure for applying a plating treatment to the inside of the through-hole This is a method for forming a through hole.

  According to a second aspect of the present invention, in addition to the first aspect, a plurality of grooves for increasing the surface area are formed on the inner wall surface of the through hole between the procedure of forming the through hole and the procedure of performing the plating process. A method for forming a through hole is characterized in that a procedure is executed.

  According to a third aspect of the present invention, in addition to the second aspect, the plurality of grooves are formed by meandering a router along the outer peripheral surface of the through hole. is there.

  According to a fourth aspect of the present invention, in addition to the second aspect, the plurality of grooves are formed with a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and then the through hole is formed. The through hole is formed by forming the pilot hole as the groove.

  According to a fifth aspect of the present invention, in the step of laminating the multilayer printed wiring board, a layer for through-hole conduction is formed at a location where a through-hole is to be formed in a layer to be electrically conducted, and the layer need not be electrically conducted. A pattern for reinforcing plating is formed at a through hole formation planned location of the multi-layer structure, a through hole is formed at the through hole planned formation location, and a plating treatment is applied to the inside of the through hole. A multilayer printed wiring board having a through hole.

  According to a sixth aspect of the present invention, in addition to the fifth aspect, a multilayer printed wiring board is characterized in that a plurality of grooves for increasing the surface area are formed in the wall surface of the through-hole in the previous stage of the plating process. It is.

  According to a seventh aspect of the present invention, in addition to the sixth aspect, the plurality of grooves are formed by meandering a router along the outer peripheral surface of the through hole. .

  According to an eighth aspect of the present invention, in addition to the sixth aspect, the plurality of grooves are formed with a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and thereafter the through hole. The multilayer printed wiring board is characterized in that the prepared hole is the groove.

  According to a ninth aspect of the present invention, in the step of laminating the multilayer printed wiring board, a procedure for forming a through-hole conduction pattern at a place where a through-hole is to be formed in a layer to be electrically conducted, and a through-hole at the place where the through-hole is to be formed A through hole, a step of forming a plurality of grooves for increasing the surface area on the inner wall surface of the through hole, and a step of plating the inner side of the through hole. This is a hole forming method.

  According to a tenth aspect of the present invention, in addition to the ninth aspect, the plurality of grooves are formed by meandering a router along the outer peripheral surface of the through hole. is there.

  According to an eleventh aspect of the present invention, in addition to the ninth aspect, the plurality of grooves are formed with a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and thereafter the through hole. The through hole is formed by forming the pilot hole as the groove.

  According to a twelfth aspect of the present invention, in the step of laminating the multilayer printed wiring board, a multilayer structure is formed by laminating after forming a through-hole conduction pattern at a through-hole formation scheduled portion of the electrically conducting layer, A through hole is formed by forming a through hole at a location where a through hole is to be formed, forming a plurality of grooves for increasing the surface area on the inner wall surface of the through hole, and plating the inside of the through hole. It is a multilayer printed wiring board characterized by having.

  According to a thirteenth aspect of the present invention, in addition to the twelfth aspect, the plurality of grooves are formed by meandering a router along the outer peripheral surface of the through hole. .

  According to a fourteenth aspect of the present invention, in addition to the twelfth aspect, the plurality of grooves form a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and then the through hole. The multilayer printed wiring board is characterized in that the prepared hole is the groove.

  According to the present invention, when a through hole is formed, a plating strengthening pattern is formed on a layer that does not need to be electrically connected to a metal that is conventionally plated only by an electrically conductive layer. Since this part is also metal-bonded with the plating, the adhesion of the plating is increased, and even if internal pressure due to gas from the substrate is applied, the phenomenon of swelling near the center of the through-hole wall surface is prevented. Moreover, the occurrence of corner cracks can be prevented.

  In addition, after forming the through hole for the through hole, by forming a plurality of grooves in the through hole, the surface area of the inner wall surface of the through hole can be increased, and the adhesion force of the plating is further increased. Is obtained.

  In the method for forming a through hole according to the present invention, it is necessary to form a through hole conduction pattern at a place where a through hole is to be formed in a layer to be electrically conducted and to be electrically conducted in the lamination step of the multilayer printed wiring board. A procedure for forming a multi-layered structure by forming a plating reinforcing pattern at a through hole formation planned portion of a non-layer, a procedure for forming a through hole at the through hole formation planned portion, and a plating treatment inside the through hole It is characterized by performing the procedure. Hereinafter, it demonstrates in detail based on drawing.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the procedure of the through hole forming method according to the present invention, which will be described in order from FIG. FIG. 1A shows a state before the formation of a through hole that electrically connects the outermost layers with a four-layer printed wiring board 10 as an example of a multilayer printed wiring board. As shown in FIG. 1 (a), through-hole conduction patterns 11 and 12 are previously formed at a place where a through-hole is to be formed in a layer to be electrically connected by a through-hole among the four layers of the printed wiring board. Form it. The through-hole conduction patterns 11 and 12 are connected to other patterns in each layer.

  In addition, in the four layers of the printed wiring board, a layer that does not need to be electrically connected by a through hole is previously formed with a plating strengthening pattern 17 at a place where the through hole is to be formed. Since the plating strengthening pattern 17 is a pattern that is not originally required, it is independent of other patterns in the formed layer.

  Next, as shown in FIG. 1B, the conduction patterns 11, 12, the plating strengthening pattern 17, and the substrate 15 are formed at positions where the through-hole conducting patterns 11, 12 and the plating strengthening pattern 17 are formed. A through-hole 13 is drilled so as to pass through.

  Thereafter, as shown in FIG. 1 (c), by applying plating 14 to the inside of the through hole 13, the through-hole conduction patterns 11 and 12, and the plating strengthening pattern 17 and the plating 14 are metal-bonded to each other. A hole 16 is formed. Through holes 16, the conductive patterns 11 and 12 are electrically connected to each other so that the outermost layers can be electrically connected to each other.

  When the through hole shown in FIG. 1C is formed as described above, the pressure is applied from the inside of the substrate to the plated portion as indicated by the arrow in FIG. 1D due to the generation of gas from the substrate material. May join. However, in the present invention, not only the through-hole conduction patterns 11 and 12 but also the plating strengthening pattern 17 has metal bonding with the plating 14, so that the structure is strong against pressure from the inside. .

  That is, the phenomenon that the vicinity of the center of the wall surface of the through hole swells can be prevented, and the pressure can be distributed at the four plating joints indicated by the dashed circles in FIG. Generation of cracks can be prevented. Thereby, it is possible to prevent the peeling of the plating.

  In the first embodiment, the plating strengthening pattern 17 is provided to improve the adhesion of the plating inside the through hole. However, in the second embodiment, the plating adhesion is increased by another method. ing.

  FIG. 2A is a schematic diagram when the through-hole conduction pattern 11 portion of the printed wiring board in the state of FIG. 1A is observed from above. When a through hole is formed, since it may be a long hole that is long in one direction as well as a circle (a broken hole shown in FIG. 2A is a through hole formation planned position), it is shown in FIG. 2A. As described above, the through-hole conduction pattern 11 is also shaped to match the elongated hole.

  The through holes are formed in the order of formation of the through holes 13 in the state shown in FIG. 2A. After the through holes 13 are formed, the inner wall surface of the through holes 13 is processed by a router. At this time, a plurality of grooves 18 are formed in the wall surface portion of the through hole 13 as shown in FIG. Alternatively, as shown in FIG. 2 (b-1), by forming a plurality of pilot holes 19 so as to overlap the wall surface of the through-hole formation planned position and then forming the through-hole 13, A plurality of grooves 18 are formed in the wall surface portion.

  As described above, in the state where the plurality of grooves 18 are formed in the wall surface portion of the through hole 13, the inside of the through hole 13 is plated as shown in FIG. By forming the plurality of grooves 18, the surface area of the inner wall surface of the through hole is increased, the adhesion of the plating 14 is increased, and the peeling of the plating 14 can be prevented.

  In the example shown in FIG. 2, the plurality of grooves 18 are formed in the straight portion of the elongated through-hole 13, but this is more likely to reduce the adhesion of plating in the straight portion than in the curved portion. Is taken into account. However, the present invention is not limited to this embodiment, and the portion where the groove 18 is formed may be any portion of the wall surface of the through hole 13. In addition, in the example of FIG. 2, the groove 18 is formed in the same direction as the through hole 13, but the present invention is not necessarily limited to this, and the groove 18 is formed on the inner wall surface of the through hole 13. If possible, the direction (angle) may be any.

  By implementing both the configuration in which the plating reinforcing pattern 17 according to the first embodiment is provided and the configuration in which the plurality of grooves 18 are formed in the inner wall surface of the through hole 13 according to the second embodiment, the adhesion strength of the plating is further improved. Can be made strong.

It is the schematic diagram which showed the procedure of formation of the through hole by this invention. FIG. 5 is a schematic diagram illustrating a procedure for forming a plurality of grooves 18 on a wall surface inside a through hole 13 to form a through hole. It is the schematic diagram showing the formation procedure of the conventional through hole. It is a schematic diagram showing an example of the shape of a through hole.

DESCRIPTION OF SYMBOLS 10 ... Print wiring board, 11, 12 ... Through-hole conduction pattern, 13 ... Through-hole, 14 ... Plating, 15 ... Board | substrate, 16 ... Through-hole, 17 ... Plating reinforcement | strengthening pattern, 18 ... Groove, 19 ... Pilot hole.

Claims (14)

  In the layering stage of multilayer printed wiring boards, a pattern for through-hole conduction is formed at a location where a through-hole is to be formed in an electrically conducting layer, and plating is performed at a location where a through-hole is to be formed in a layer that does not need to be electrically conducted. A procedure for forming a multilayer structure by forming a reinforcing pattern, a procedure for forming a through hole at a location where the through hole is to be formed, and a procedure for performing a plating process on the inside of the through hole are performed. A through hole forming method.   2. The through according to claim 1, wherein a step of forming a plurality of grooves for increasing a surface area on an inner wall surface of the through hole is executed between the step of forming the through hole and the step of performing the plating process. How to form holes.   3. The method of forming a through hole according to claim 2, wherein the plurality of grooves are formed by subjecting a router to meandering along the outer peripheral surface of the through hole.   The plurality of grooves are formed as a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and then the through hole is formed as the groove. The method for forming a through hole according to claim 2.   In the layering stage of multilayer printed wiring boards, a pattern for through-hole conduction is formed at a location where a through-hole is to be formed in an electrically conducting layer, and plating is performed at a location where a through-hole is to be formed in a layer that does not need to be electrically conducted. A multilayer structure is formed by forming a reinforcing pattern, and a through hole is formed at a location where the through hole is to be formed, and a through hole is formed by plating the inside of the through hole. Multilayer printed wiring board.   6. The multilayer printed wiring board according to claim 5, wherein a plurality of grooves for increasing the surface area are formed in the wall surface of the through hole in a previous stage of the plating process.   The multilayer printed wiring board according to claim 6, wherein the plurality of grooves are formed by subjecting a router to meandering along the outer peripheral surface of the through hole.   The plurality of grooves are formed as a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and then the through hole is formed as the groove. The multilayer printed wiring board according to claim 6.   In the step of laminating the multilayer printed wiring board, a procedure for forming a through-hole conduction pattern at a location where a through-hole is to be formed in an electrically conducting layer, a procedure for forming a through hole at the location where the through-hole is to be formed, and the penetration A method for forming a through hole, comprising: a step of forming a plurality of grooves for increasing a surface area on an inner wall surface of a hole; and a step of performing a plating process on the inside of the through hole.   The method for forming a through hole according to claim 9, wherein the plurality of grooves are formed by subjecting a router to meandering along an outer peripheral surface of the through hole.   The plurality of grooves are formed as a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and then the through hole is formed as the groove. The method for forming a through hole according to claim 9.   In the step of laminating the multilayer printed wiring board, a through hole conduction pattern is formed at a location where a through hole is to be formed in a layer to be electrically conducted and then laminated to form a multilayer structure. A multilayer print having a plurality of grooves for increasing the surface area on the inner wall surface of the through hole, and a through hole formed by plating the inside of the through hole. Wiring board.   The multilayer printed wiring board according to claim 12, wherein the plurality of grooves are formed by subjecting a router to meandering along an outer peripheral surface of the through hole.   The plurality of grooves are formed as a plurality of pilot holes in a portion located on the outer peripheral surface of the through hole in advance before forming the through hole, and then the through hole is formed as the groove. The multilayer printed wiring board according to claim 12.

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