JP2009088337A - Printed circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed circuit board and its manufacturing method for actualizing fine layer-to-layer connection with high density while coping with displacement during machining without increasing the number of processes. <P>SOLUTION: The multilayer printed circuit board comprises a layer-to-layer connection part formed by a through-hole 4 and a metal layer formed on the inner wall of the through-hole, the layer-to-layer connection part having at least two electrically insulated wiring circuits 2a on the inner wall of the through-hole, the through-hole being planarly shaped to be linear and slender at an approximately equal width, the wiring circuit being formed in the direction of the depth of the through-hole to electrically connect two or more electrode layers to each other including the surface layer electrode layers on both sides of the multilayer printed circuit board. Its manufacturing method is provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a printed wiring board and a manufacturing method thereof, and more particularly to a multilayer printed wiring board that performs electrical connection between layers and a manufacturing method thereof.

  In recent years, when electrical connection between layers is performed in a multilayer printed wiring board, the inner wall of a through hole or a non-through hole, generally referred to as a through hole or a via hole, is coated with a metal electrode layer using a technique such as electrolytic plating. Structure is used. A circular electrode layer generally called a land is formed around the hole of such a through hole or via hole.

  This land is provided to reliably maintain the electrical connection between layers with respect to the positional deviation between the hole and the wiring circuit. In consideration of this positional deviation, the diameter of the land has a size of 225 μm (reference: 2007 edition, Japan mounting technology roadmap) or more even in the finest double-sided printed wiring board in the range that can be mass-produced at present. The size of the land is determined by the positional deviation in the formation of the hole, but it is difficult to reduce the diameter of the land as long as the machining positional deviation is unavoidable.

  Such a double-sided printed wiring board that performs interlayer connection using conventional through-holes is usually manufactured by the following steps. That is, first, as shown in FIG. 6A (1), a double-sided copper-clad laminate 43 having copper foils 42 with a thickness of about 4 μm is prepared on both sides of an insulating base material 41 such as polyimide with a thickness of about 25 μm.

  Next, as shown in FIG. 6A (2), a through-hole 44 having a diameter of about 50 μm is formed on the double-sided copper-clad laminate 43 by using a direct laser processing method, and subsequently about 6 μm by electrolytic copper plating. By forming the plated copper 45, a double-sided copper-clad laminate 43a having an interlayer connection is obtained.

  Next, as shown in FIG. 6A (3), a photosensitive dry film having a thickness of about 20 μm is laminated on both sides of the double-sided copper-clad laminate 43a, and then an etching resist 46 is formed by performing exposure and development. To do. At this time, it is inevitable that a positional deviation occurs between the through hole 44 and the etching resist 46. An etching resist 46 for forming lands is formed above and below the through-hole 44 in order to ensure electrical connection between layers with respect to this positional deviation.

  Subsequently, as shown in FIG. 6B (4), the plated copper 45 and the copper foil 42 are etched using an ordinary subtractive etching method to form a wiring circuit 42a and a land 42b, and then a photosensitive dry film. 46 is peeled off.

  Thereafter, as shown in FIG. 6B (5), a solder resist 47 is formed, and surface treatment such as solder plating, tin plating, nickel plating, gold plating, etc. is performed on the terminal surfaces of component mounting lands and connectors as required. Apply. Through the above steps, a double-sided printed wiring board 43b in which interlayer connection is performed by a general through hole is obtained.

  FIG. 7A shows a wiring circuit of a double-sided printed wiring board in which a large number of wirings 110 are interlayer-connected from the semiconductor chip 100 mounted on the printed wiring board using through holes and connected to the opposite side of the printed wiring board. It is the top view which showed an example.

  In such a case, since the land of the through hole is large, as shown in FIG. 7B, the lands 112 formed at the end of the wiring 111 are arranged obliquely.

At present, even the finest double-sided printed wiring boards that can be mass-produced have a land diameter of 225 μm or more. Accordingly, when the finest wiring pitch is 60 μm (wiring width 30 μm, inter-wiring gap 30 μm) or more, it is about 3.2 mm ² or more for routing 20 layers and performing interlayer connection. The substrate area is required.

  As a method of forming a landless through hole in response to such a current situation, in Patent Document 1, a wiring circuit is first formed on a double-sided copper-clad laminate, a plating mask is formed, and then drilling or the like is performed. Discloses a method of forming a hole and performing interlayer connection by electrolytic plating after conductive treatment. According to such a method, the electrical connection between layers can be performed without forming a land.

  As a method of connecting a plurality of wirings with one through hole, Patent Document 2 discloses a method of forming a plurality of electrically insulated wirings on the wall surface of the through hole. However, when a large number of wirings are connected through one through hole, the influence of positional misalignment between the through hole hole and the wiring circuit is great.

  FIG. 8A and FIG. 8B are conceptual plan views showing the influence on positional deviation when four wirings are connected through the through hole.

  FIG. 8A (1) shows a plan view in which an etching resist 52 is formed on a through hole 51 that has been subjected to interlayer connection by plating, and etching is performed later to connect four wirings through one through hole. FIG. The width of the etching resist 52 is assumed to be about 50 μm and the through hole diameter is about 300 μm. As described later, this means that a stable connection cannot be made unless the through-hole diameter is about this level, and therefore, it is unavoidable to increase the through-hole diameter for many wiring connections.

  FIG. 8A (2) is a plan view showing the exposure area 53 from the back surface when the exposure from the back surface has a deviation of about 25 μm in the upper right direction of the drawing.

  FIG. 8A (3) is a plan view showing the assumed through hole 54 in the most severe case where the through hole 51 is displaced by about 75 μm in the lower left direction of the figure. When such the most severe misalignment occurs, the etching resist gap 55 for ensuring insulation between wirings by etching becomes very narrow. For this reason, it is difficult to make the diameter of the through hole 51 smaller.

  FIG. 8B (4) is a plan view showing a region 56 where the through hole 51 may be formed when the through hole 51 is displaced by ± 75 μm. Since the diameter of the region 56 is as large as 450 μm, and there is a possibility that the through hole 51 is formed inside the region 56, other wiring circuits cannot be formed, and the wiring to be connected is etched resist. It must be pulled out of the region 56 as in 52a.

FIG. 8B (5) is an example of wiring routing when four wirings are drawn in one direction like the etching resist 52b outside the region 56. FIG. In such a case, since the wiring circuit is routed outside the region 56 having a diameter of 450 μm, it can be understood that a substrate area having a diameter of about 600 μm is required for four wiring connections.
JP 2004-146668 A JP-A-11-251702

  The conventional interlayer connection methods described above have problems.

  The method disclosed in Patent Document 1 is disadvantageous in terms of cost because it increases the number of processes, and it is necessary to escape a wiring circuit in the vicinity thereof without considering a land even if a land is not formed. Therefore, the problem cannot be solved.

  Further, in the method disclosed in Patent Document 2, the influence of exposure misalignment and through hole processing misalignment is large, and an increase in the diameter of the through hole is unavoidable for a large number of wiring connections. It can be seen that increasing the diameter of the through-hole is contrary to the reduction in size and density of the substrate, which is a problem, and does not lead to the solution of the problem.

  The present invention has been made in consideration of the above-described points. A multilayer printed wiring board capable of dealing with a positional deviation during processing without increasing the number of steps and capable of high-density and fine interlayer connection and a method for manufacturing the same The purpose is to provide.

  In order to achieve the above object, the present application provides the following invention.

The first invention is
A multilayer printed wiring board in which an interlayer connection is formed by a through hole and a metal layer formed on the inner wall of the through hole,
1) The interlayer connection portion includes at least two or more electrically insulated wiring circuits on the inner wall of the through hole.
2) The through-hole is an elongated shape having a straight planar shape and a substantially equal width,
3) The wiring circuit is formed along the depth direction of the through hole, and electrically connects two or more electrode layers including surface electrode layers on both surfaces of the multilayer printed wiring board.
Multilayer printed wiring board, characterized by
I will provide a.

The second invention is
In the method for producing a multilayer printed wiring board having a plurality of layers including a surface electrode layer,
1) Prepare a multilayer wiring substrate in which no wiring circuit is formed on the surface electrode layer,
2) In the multilayer wiring substrate, a planar shape is linear and a through hole having an elongated shape with a substantially equal width is formed.
3) Electrolytic copper plating treatment is performed on the through holes to make electrical connection between the layers,
4) A photosensitive resin material is used to form a resist pattern including an etching resist forming portion and an etching resist non-forming portion on the inner wall of the through hole
5) A wiring circuit for interlayer connection is formed by etching using the resist pattern.
A method for producing a multilayer printed wiring board, characterized in that
I will provide a.

The third invention is
In the method for producing a multilayer printed wiring board having a plurality of layers including a surface electrode layer,
1) Prepare a multilayer wiring substrate in which no wiring circuit is formed on the surface electrode layer,
2) Form a through-hole that is an elongated shape having a straight planar shape and a substantially equal width with respect to the multilayer wiring substrate,
3) forming a plating mask in the through hole;
4) Using the plating mask, by performing an electrolytic copper plating process on the through hole, an electrical connection between layers is performed and a wiring circuit of the surface electrode layer is formed.
5) Perform flash etching to ensure insulation between wirings in the wiring circuit.
A method for producing a multilayer printed wiring board is provided.

  Due to these features, the present invention has the following effects.

  The present invention eliminates the need for highly accurate alignment between the through-hole and the wiring while being a landless, allows a plurality of wiring circuits to be connected with high density, and does not require a special process and is cost-effective. In addition, a multilayer printed wiring board that is also advantageous can be manufactured inexpensively and stably.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Here, an explanation will be given by taking a double-sided printed wiring board having the simplest structure as an example of a multilayer printed wiring board, but the present invention can also be applied to a multilayer printed wiring board having three or more layers.

  1A and 1B are conceptual diagrams showing a manufacturing process of a printed wiring board in the first embodiment of the present invention. This printed wiring board is manufactured by the following steps. First, as shown in FIG. 1A (1), a double-sided copper-clad laminate 3 having copper foils 2 having a thickness of about 4 μm is prepared on both sides of an insulating base material 1 made of epoxy, polyimide, etc. and having a thickness of about 25 μm.

  In addition, the material of the insulating base material 1 is not necessarily limited to epoxy and polyimide, and can be properly used according to the application. For example, in an application where it is necessary to reduce dielectric loss during high-speed signal transmission, a double-sided copper-clad laminate based on a liquid crystal polymer or the like can be used as a low dielectric loss tangent material.

  Next, as shown in FIG. 1A (2), through-holes 4 for later electrical connection between layers are formed by using a direct laser processing method such as a UV-YAG laser. FIG. 1A (2) shows the outline of the through hole 4 hidden by the copper foil 2 and the insulating base material 1 by dotted lines.

  The through-hole 4 is preferably an elongated rectangle as an example of an elongated shape having a straight planar shape and a substantially equal width, that is, a rectangle having a width of about 20 to 500 μm and a length of about 0.1 to 50.0 mm or a shape close thereto. This is a shape for interlayer connection of a plurality of wirings using both side surfaces of one through hole, and the length of the through hole can be adjusted according to the number of wirings to be connected. In the embodiment shown in FIG. 1, the through-hole 4 has a long rectangular shape with a width of 50 μm and a length of 1.0 mm.

  The means for forming the through-hole 4 is not limited to the UV-YAG laser, and processing with a carbon dioxide laser or a drill is performed in consideration of the required processing width, processing length, throughput, processing accuracy, quality, and the like. Etc. can be used alone or in combination.

  Next, as shown in FIG. 1A (3), as a pretreatment for obtaining interlayer connection by electrolytic plating, desmear treatment and conductive treatment are performed, and subsequently, plated copper 5 of about 6 μm is formed by electrolytic plating treatment. Form. Through the above steps, the double-sided copper clad laminate 3a having an interlayer connection is obtained.

  Next, as shown in FIG. 1B (4), a dry film in which a photosensitive resin material is formed into a film with a thickness of about 20 μm is laminated on both sides of the double-sided copper-clad laminate 3a, and then exposed and developed from both sides. Thus, the pattern of the etching resist 6 is formed in a direction orthogonal to the longitudinal direction of the through hole 4. FIG. 1B (4) shows the outline of the etching resist 6 hidden by the insulating base material 1, the copper foil 2, and the plated copper 5 by dotted lines.

  Since the through-hole 4 also forms a pattern of the etching resist 6 inside, in the laminate, the photosensitive resin material is passed through the through-hole 4 using a vacuum laminator or the like so that no void or the like is generated inside the through-hole 4. Fill inside.

  Further, depending on the depth of the through hole 4, it may be possible that sufficient exposure cannot be performed up to the center of the through hole 4, and the pattern of the etching resist 6 cannot be formed inside the through hole 4. If the amount of exposure is excessive as a countermeasure, the etching resist 6 on the substrate surface becomes thick or a sufficient resist gap cannot be secured.

  In such a case, a dry film using a photosensitive resin material having high exposure sensitivity and high fluidity is first laminated, and the inside of the through hole 4 is filled with the photosensitive resin material to flatten the substrate surface. Then, by laminating a dry film using a photosensitive resin material having low exposure sensitivity later, the photosensitive resin material in the through hole 4 can be accelerated.

  Also, by preparing a dry film with a laminated structure of a photosensitive resin material with high exposure sensitivity and a photosensitive resin material with low exposure sensitivity, laminating with the photosensitive resin material side with high exposure sensitivity facing the substrate side The inside of the through hole 4 can be preferentially filled with a photosensitive resin material having a high exposure sensitivity to solve the above problem.

  When such measures are taken, the amount of light reaching the inside of the through hole 4 is estimated from the light transmittance and thickness of the photosensitive resin material, and a photosensitive resin material having an exposure sensitivity corresponding to the light amount is selected. Is desirable.

  The photosensitive resin material is preferably a negative photosensitive resin material in which the light shielding portion is removed by development. This is because when exposed from both sides inside the through-hole 4, the portion that is shielded from light by the exposure position deviation on both sides is reduced, so that the positive type may be insufficient as a subsequent etching resist. is there.

  It should be noted that the width and gap of the etching resist 6 formed at this time must be determined in consideration of the positional deviation due to exposure from both sides. FIG. 2 is a conceptual diagram when a positional shift occurs in exposure from both sides. Since the inside of the through-hole 4 is exposed from both sides, the exposed part is increased by the amount of positional deviation, and the light-shielding part (part removed by development) is reduced.

  Further, since the pattern of the etching resist 6 is formed inside the through hole 4, an exposure method with a deep focal depth is preferable, and it is most preferable to use a parallel light exposure machine.

  Therefore, in Example 1, a parallel light exposure machine capable of performing double-sided simultaneous exposure that aligns the exposure masks on both sides with high accuracy was used, and thereby the exposure position deviation on both sides could be suppressed to within ± 25 μm. . And even when a positional deviation of 25 μm occurs, the design value of the gap of the etching resist 6 is set to 50 μm so that the gap of the etching resist 6 inside the through hole 4 can be secured, and copper is etched from this gap. In order to form a wiring circuit, the width of the etching resist 6 was set to 40 μm (pitch 90 μm).

  In this way, ten fine patterns of the etching resist 6 were formed on both sides of the through hole 4 having a length of 1.0 mm. The number of patterns of the etching resist 6 becomes half of the number of wirings for performing interlayer connection in the through holes 4 by performing etching later. Considering the purpose of performing high-density interlayer connection, it is considered that the number of patterns of the etching resist 6 is preferably 2 or more, that is, the number of wirings to be connected is 4 or more.

  Since the length of the through-hole 4 is 1.0 mm, even if 10 etching resists 6 are formed, a margin of 75 μm is created at both ends in the length direction, and the etching resist 6 formed by exposure is penetrated. The positional deviation from the hole 4 can be absorbed with this margin.

  With such a structure, even when the positional deviation at the time of formation of the through hole 4 is larger, it can be dealt with by increasing the length of the through hole 4, and the positional deviation affects the wiring density of the interlayer connection. Absent. Through the above steps, a double-sided copper-clad laminate 3b on which an etching resist is formed is obtained.

  Next, as shown in FIG. 1B (5), the wiring circuit 2a was formed with respect to the copper foil 2 and the plated copper 5 by the etching method by the normal subtractive method. FIG. 1B (5) illustrates the outlines of the wiring circuit 2a and the etching resist 6 hidden by the insulating base material 1 by dotted lines.

  As a result, the through-holes 4 could be electrically connected between the layers with respect to 10 wiring circuits per side and 20 wirings on both sides. The wirings on both sides at this time have a very high pitch of 90 μm, and no land for interlayer connection is required. In addition, by adjusting the length of the through hole, there is no influence of positional deviation, and no special complicated process is required, which is advantageous in terms of cost.

  Next, as shown in FIG. 1B (6), the etching resist 6 is peeled off, and a solder resist (not shown) is formed at a necessary location, and solder plating is applied to the terminal surfaces of component mounting lands and connectors as necessary. Surface treatment such as tin plating, nickel plating, gold plating is performed. Through the above steps, the double-sided printed wiring board 3c in which the wiring circuits are interlayer-connected with high density is obtained.

  For an application in which lands are arranged (see FIGS. 7A and 7B), a circuit layout as shown in FIGS. 4A and 4B is preferable.

  According to the present invention, a land is not necessary for the interlayer connection of the wiring, the width of the through hole of the interlayer connection portion is 50 μm, and the margin from the through hole to the wiring is 75 μm (considering the positional deviation of 75 μm when forming the through hole). However, the wiring gap in the vicinity of the through hole can be suppressed to 200 μm.

  Therefore, compared to the conventional configuration in which similar wiring is routed through through holes and via holes (FIG. 7), the wiring routing area can be reduced to half or less. If the length of the through hole is increased, a larger number of wirings can be connected, and interlayer connection can be made to a large number of wirings at a very high density.

  FIG. 5 shows an example of an application in which the present invention is combined with the outer shape processing of the end portion of the printed wiring board. Thus, by processing the center of the through-hole, a wiring circuit can be formed on the side surface of the outer end of the printed wiring board.

  When connecting a printed wiring board to a small electronic device, a structure that connects to an external circuit or cable at the end of the printed wiring board is often used. Wiring circuits that must be connected to the back side using holes and via holes can be easily connected to the back side at the edge of the product, and the wiring circuit of the printed wiring board can be reduced in size and simplified. is there.

  The above process and circuit layout eliminates the need for high-precision alignment between the through-holes and the wiring while being landless, allows multiple wiring circuits to be connected to each other at high density, and eliminates the need for special processes. The multilayer printed wiring board can be stably manufactured advantageously in terms of cost.

  FIG. 3A and FIG. 3B are conceptual diagrams showing the manufacturing process of the printed wiring board in the second embodiment of the present invention. This printed wiring board is manufactured by the following steps. That is, first, as shown in FIG. 3A (1), a double-sided conductive base material 23 having a conductive layer 22 of about 1 μm thickness on both sides of an insulating base material 21 made of epoxy, polyimide, etc. and having a thickness of about 25 μm is prepared. To do.

  As the double-sided conductive base material 23, a substrate in which nickel, chromium, zinc or the like is formed on both surfaces of the insulating base material 21 by sputtering, and plated copper of about 1 μm is formed thereon by electrolytic copper plating or the like is used. be able to.

  Next, as shown in FIG. 3A (2), a through-hole 24 for later electrical connection between layers is formed by using a direct laser processing method using a UV-YAG laser or the like. In Example 2, the width of the through hole 24 was 50 μm and the length was 1.0 mm.

  Next, as shown in FIG. 3B (3), as a pretreatment for obtaining interlayer connection by electrolytic plating, desmear treatment and conductive treatment are performed, and then a photosensitive resin material is formed on both sides with a thickness of about 20 μm. By laminating the film-formed dry film and then performing exposure and development from both sides, a pattern of the plating mask 25 is formed in a direction orthogonal to the longitudinal direction of the through hole 24.

  In addition to the dry film, a positive photosensitive resin material in which an exposed portion is removed by development can be applied to the photosensitive resin material. At this time, the width and gap of the plating mask 25 to be formed must be determined in consideration of positional deviations due to exposure from both sides. Since the inside of the through-hole 24 is exposed from both sides, the exposed part is increased by the amount of positional deviation, and the light-shielding part (part removed by development) is reduced.

  In Example 2, a parallel light exposure machine capable of performing the double-sided simultaneous exposure method is used, and the exposure position deviation between both sides can be suppressed to within ± 25 μm. Therefore, even when a positional deviation of 25 μm occurs, the design value of the gap of the plating mask 25 is set to 50 μm so that the gap of the plating mask 25 inside the through hole 24 can be ensured to 25 μm.

  Further, if the positional deviation occurs beyond the width of the plating mask 25, the upper and lower wirings cannot be connected inside the through hole 24. From this, the width of the plating mask 25 was set to 40 μm (pitch 90 μm).

  In this way, nine fine patterns (pitch of 90 μm) of the plating mask 25 are formed on each side of the through hole 24 having a length of 1.0 mm, and the plating mask is also formed on both ends of the through hole 24. Formed. Through the above steps, the inside of the through hole is made conductive to obtain a double-sided conductive base material 23a on which a plating mask is formed.

  Next, as shown in FIG. 3B (4), a wiring circuit 26 having a thickness of about 11 μm by electrolytic plating is applied to a portion of the double-sided conductive substrate 23b and the through hole 24 where the plating mask 25 is not formed. Next, the plating mask 25 is peeled off, and flash etching of about 2 μm is performed. By this flash etching, the conductive layer 22 where the wiring circuit 26 is not formed is removed, and insulation between the wiring circuits is ensured.

  As a result, interlayer electrical connection could be made to the through-hole 24 with as many as 10 wiring circuits per side and 20 wirings on both sides.

  Subsequently, a solder resist (not shown) is formed at a necessary location, and surface treatment such as solder plating, tin plating, nickel plating, gold plating or the like is performed on the terminal surfaces of component mounting lands and connectors as necessary. Through the above steps, a double-sided printed wiring board 23b in which wiring circuits are interlayer-connected with high density is obtained.

  For an application for arranging lands (see FIGS. 7A and 7B), it is preferable to use a circuit layout as shown in FIGS. 4A and 4B, as in the first embodiment.

  The above process and circuit layout eliminates the need for high-precision alignment between the through-holes and the wiring while being landless, allows multiple wiring circuits to be connected to each other at high density, and eliminates the need for special processes. The multilayer printed wiring board can be stably manufactured advantageously in terms of cost.

The perspective view of the manufacturing method of the printed wiring board by the 1st Example of this invention. The perspective view of the manufacturing method of the printed wiring board by the 1st Example of this invention. The perspective view of the manufacturing method of the printed wiring board by the 1st Example of this invention. The perspective view of the manufacturing method of the printed wiring board by the 2nd Example of this invention. The perspective view of the manufacturing method of the printed wiring board by the 2nd Example of this invention. The top view of the circuit layout of the printed wiring board which connects many wiring by the 1st and 2nd Example of this invention. The enlarged plan view of the circuit layout of the printed wiring board which connects many wiring by the 1st and 2nd Example of this invention. The top view of the circuit layout of the printed wiring board which connects many wiring by the 1st and 2nd Example of this invention. The conceptual sectional drawing of the manufacturing method of the conventional printed wiring board. The conceptual sectional drawing of the manufacturing method of the conventional printed wiring board. The conceptual top view of the circuit layout of the printed wiring board which connects many wiring. The conceptual top view of the circuit layout of the printed wiring board which connects many wiring. The conceptual top view in the case of connecting several wiring by one through hole. The conceptual top view in the case of connecting several wiring by one through hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation base material 2 Copper foil 2a Wiring circuit 3 Double-sided copper clad laminated board 3a Double-sided copper-clad laminated board 3b with which interlayer connection was taken Double-sided copper clad laminated board 3c in which the etching resist was formed Double-sided printed wiring board 4 Through-hole 5 Plating copper 6 Etching resist 21 Insulating base material 22 Conductive layer 23 Double-sided conductive base material 23a Double-sided conductive base material 23b with plating mask formed Double-sided printed wiring board 24 Through hole 25 Plating mask 26 Wiring circuit 41 Insulating base material 42 Copper foil 42a Wiring circuit 42b Land 43 Double-sided copper-clad laminate 43a Double-sided copper-clad laminate 44 with interlayer connection Through hole 45 Plating copper 46 Etching resist 47 Solder resist 51 Through hole 52 Etching resist 52a Etching resist 52b Etching resist 53 Exposure from the back surface Etch that could remain by Areas which may etch resist gap 56 through holes in the case of through-hole 55 severe misalignment when the resist 54 misalignment has occurred has occurred is formed

Claims (7)

A multilayer printed wiring board in which an interlayer connection is formed by a through hole and a metal layer formed on the inner wall of the through hole,
1) The interlayer connection portion has at least two or more electrically insulated wiring circuits on the inner wall of the through hole,
2) The through-hole is an elongated shape having a straight planar shape and a substantially equal width,
3) The wiring circuit is formed along the depth direction of the through hole, and electrically connects two or more electrode layers including surface electrode layers on both surfaces of the multilayer printed wiring board.
A multilayer printed wiring board characterized by that. In the multilayer printed wiring board according to claim 1,
A wiring circuit that electrically connects two or more electrode layers including a surface electrode layer is formed on the side surface of the outer edge of the multilayer printed wiring board,
A multilayer printed wiring board characterized in that the wiring circuit is formed on an end surface of the outer end portion. In the method for producing a multilayer printed wiring board having a plurality of layers including a surface electrode layer,
1) Prepare a multilayer wiring substrate in which no wiring circuit is formed on the surface electrode layer,
2) In the multilayer wiring substrate, a planar shape is linear and a through hole having an elongated shape with a substantially equal width is formed.
3) Electrolytic copper plating treatment is performed on the through holes to make electrical connection between the layers,
4) A photosensitive resin material is used to form a resist pattern including an etching resist forming portion and an etching resist non-forming portion on the inner wall of the through hole
5) A wiring circuit for interlayer connection is formed by etching using the resist pattern.
A method for producing a multilayer printed wiring board, comprising: In the method for producing a multilayer printed wiring board having a plurality of layers including a surface electrode layer,
1) Prepare a multilayer wiring substrate in which no wiring circuit is formed on the surface electrode layer,
2) Form a through-hole that is an elongated shape having a straight planar shape and a substantially equal width with respect to the multilayer wiring substrate,
3) forming a plating mask in the through hole;
4) Using the plating mask, by performing electrolytic copper plating on the through-holes, electrical connection between layers is performed and a wiring circuit of the surface electrode layer is formed.
5) Perform flash etching to ensure insulation between wirings in the wiring circuit.
A method for producing a multilayer printed wiring board, comprising: In the manufacturing method of the multilayer printed wiring board of Claim 3 or 4,
Forming a wiring circuit that electrically connects two or more electrode layers including the surface electrode layer on the inside of the through hole and the side surface of the outer edge of the multilayer printed wiring board;
A method for producing a multilayer printed wiring board, comprising: In the manufacturing method of the multilayer printed wiring board of Claim 3 or 4,
Fill the inside of the through hole with a photosensitive resin material with high exposure sensitivity,
A layer of a photosensitive resin material having low exposure sensitivity is formed on the surface of the multilayer wiring substrate,
A method for producing a multilayer printed wiring board, comprising: forming a resist pattern inside the through hole. In the manufacturing method of the multilayer printed wiring board of Claim 3 or 4,
Prepare a dry film with a structure in which two or more types of photosensitive resin materials with different exposure sensitivities are laminated,
Laminating the dry film on the base material so that the surface of the photosensitive resin material with high exposure sensitivity is in contact,
A method for producing a multilayer printed wiring board, comprising: forming a resist pattern inside the through hole.

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