JP2019127619A - Production method of wiring board - Google Patents

Abstract

To provide a production method of a wiring board in which a desired metal layer can be formed on the surface of a to-be-plated insulation board so that a plating jig is not shifted or fallen off from the insulation board even when the contact area of a conducting contact is small.SOLUTION: A production method of a wiring board 1 includes a plating process in which: a groundwork metal layer 7 is formed on the entire surface 3 of an insulation board 2; a pattern resist is added on the layer; an annular resist 10 is arranged so that a needle-like part 25 of a plating conduction jig 23 is not shifted; and a metal layer 19 is deposited by an electrolytic metal plating.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method of manufacturing a wiring board for forming a metal layer having a desired pattern on at least one surface of an insulating substrate made of an insulating material and having a pair of opposing surfaces.

For example, a plurality of holding members are attached to each of a pair of left and right vertical beam members having an inverted U-shaped hook at the upper end, and the pair of spring elastic portions also serving as insulating portions provided for each holding member A jig for electrolytic plating of a printed circuit board has been proposed which can coat a desired metal film on the surface of the printed circuit board held in a vertical posture between vertical beams of the above (for example, patent documents 1).
When using the above electroplating jig, during electroplating, the uniformity of the plating current distribution on the printed circuit board is improved, and the spring elasticity of the holding member is not lost even after repeated plating operations. The printed circuit board can be easily engaged and disengaged.

  However, when the electrolytic plating is performed on the surface of the wiring substrate held using the electrolytic plating jig, if the conductive contact (contact area) with the holding jig is reduced, the electrolytic plating maintenance may be performed. In some cases, the conductive contact of the tool may be displaced, or the conductive contact may be detached from the surface of the wiring board, making it impossible to supply the plating current. On the other hand, if the contact point for conduction with the holding member is increased, there is a problem that the wiring board cannot be removed after electrolytic plating.

JP-A-5-320994 (pages 1-5, FIGS. 1-4)

  The present invention solves the problems described in the background art, and even if the contact area of the conductive contact is reduced, the plating jig does not shift or fall off from the insulating substrate for plating, and the insulating substrate It is an object of the present invention to provide a method of manufacturing a wiring substrate capable of forming a desired metal layer on the surface of

Means for Solving the Problems and Effects of the Invention

In order to solve the above-mentioned problems, the present invention was conceived in consideration of forming a resist layer such as an annular shape on the surface of the wiring substrate so as to surround the conductive contact.
That is, the method for manufacturing a wiring board according to the present invention (claim 1) is a method for manufacturing a wiring board having a desired pattern on at least one surface of an insulating substrate made of an insulating material and having a pair of opposing surfaces. A method of forming a base metal layer over the entire surface of the insulating substrate, and a top surface of the base metal layer excluding the position where the metal layer is to be formed among the top surfaces of the base metal layer And a resist layer forming step of forming a metal layer resist layer for forming the metal layer, and a conductive layer resist layer exhibiting an annular, U-shaped, or C-shaped planar view. A conductive jig is brought into contact with the upper surface of the base metal layer surrounded by the conductive portion resist layer, current is supplied to the base metal layer through the conductive jig, and the insulating substrate is immersed in a predetermined electrolytic plating solution. To immerse Ri, the upper surface of the metal layer resist layer and the underlying metal layer not covered with the resist layer for the conductive portion, comprising a plating step of depositing a metal layer by electroless metal plating, and characterized in that.

According to the method of manufacturing the wiring board, the following effects (1) and (2) can be obtained.
(1) The plating step is performed in a state in which the conductive jig is in contact with the upper surface of the base metal layer surrounded by the conductive portion resist layer. There is no risk of the conductive jig shifting excessively from the insulating substrate or the conductive jig coming off even when receiving pressure or the like, and the required electrolytic plating can be reliably performed.
(2) In the plating step, the conduction jig can supply power to the base metal layer of the insulating substrate with a relatively small contact area, and the wiring board and the conduction jig after the plating step are integrated. In addition to the prevention of the problem, since the conductive jig can be easily removed from the wiring board, the processing efficiency of the plating process can be enhanced.

The insulating substrate is made of ceramic (for example, alumina or aluminum nitride) or resin (for example, polyimide or epoxy). The pair of surfaces in the insulating substrate is a relative name, and for example, one may be referred to as a surface and the other may be referred to as a back surface.
The metal layer is made of, for example, copper, silver, nickel, or gold.
Furthermore, the base plating layer is an electrode for depositing the metal layer by electrolytic plating, and is formed by, for example, electroless plating, sputtering or the like.
The metal layer resist layer and the conductive portion resist layer are formed, for example, by coating (laminating) a resin film or patterning of the resin layer by photolithography.

Furthermore, the conductive layer resist layer encloses the contact portion between the conductive jig and the underlying metal layer in order to prevent the inadvertent displacement of the conductive jig, and the pattern in plan view is annular (island shape) : Presents a circular shape (ring shape), an oval shape, an oval shape, a square shape, etc., a U shape, a C shape, or the like. The underlying metal layer having a diameter, a major diameter, or a width of about 3 mm or less surrounded by the conductive layer resist layer is located inside the conductive layer resist layer.
Further, the conductive layer resist layer is mainly formed on an ear portion excluding a product region in the insulating substrate.
In addition, the conduction jig having the single needle-like portion is, for example, a base end of a spring portion in a metal frame member (electrode jig) for immersing and holding the insulating substrate in an electrolytic plating solution. It projects from the side. On the other hand, the conduction jig having the pair of symmetrical needle-like parts is composed of the base side and an independent pinch-like or tongue-like metal fitting having a spring part and two needle-like parts.

The present invention also includes a resist layer peeling step for peeling off and removing the metal layer resist layer and the conductive portion resist layer after the plating step, and the base metal layer not covered with the metal layer. And the etching step of removing the wiring substrate.
According to this, after the plating step, the resist layers unnecessary as a product and the underlying metal layer not covered by the metal layer are removed, so that the metal desired on the surface of the insulating substrate is removed. The layer can be formed accurately and reliably. Therefore, it is possible to reliably achieve the effects (1) and (2).

Furthermore, the present invention also includes a method of manufacturing a wiring board (Claim 3), wherein the thickness of the conductive layer resist layer is at least 50 μm or more.
According to this, the conduction jig in contact with the upper surface of the base metal layer surrounded by the conductive layer resist layer does not inadvertently shift with respect to the insulating substrate or drop off the insulating substrate. Therefore, the effect (1) can be obtained with certainty.
When the thickness of the conductive portion resist layer is less than 50 μm, the needle-like portion of the conductive jig to be described later can inadvertently ride over the conductive portion resist layer. The upper limit of the thickness is set to have a thickness greater than the thickness of the metal layer formed in the plating step.

In addition, in the present invention, the plating step may have a single needle-like portion pressed by the elasticity of the proximal end on the upper surface of the base metal layer formed on one surface of the insulating substrate, or A method of manufacturing a wiring board, which is performed using the conduction jig having a pair of symmetrical needle-like portions individually contacting the upper surface of each of the base metal layers formed on both surfaces of the insulating substrate. Also included.
According to this, the conduction jig is plated with a minimum contact area on the upper surface of the base metal layer surrounded by the resist layer for the conduction part through the single or pair of symmetrical needle-like parts. Since the working current can be supplied, the effect (2) can be obtained reliably.

(A)-(C) are schematic which shows the form of the conduction | electrical_connection jig which electrically feeds to an insulated substrate. (A)-(D) are schematic which shows each manufacturing process in this invention. (A) is a perspective view which shows the manufacturing process of FIG.1 (D), (A)-(D) is the schematic which shows each manufacturing process following FIG.1 (D). (A)-(C) are the perspective views similar to Fig.3 (a) which provided the resist layer for conduction | electrical_connection parts of a different form.

Hereinafter, modes for carrying out the present invention will be described.
FIGS. 1A to 1C are schematic views showing the conductive jigs 23, 30, 33 for supplying power to the insulating substrate 2. FIG.
As shown in FIG. 1A, the insulating substrate 2 is, for example, a plate made of alumina (ceramic). The insulating substrate 2 has a rectangular front surface 3 and a back surface (front surface) 4 facing each other in plan view, and side surfaces 5 of four sides located between the peripheries thereof, and a product region that is on the center side in plan view The ear 6 having a rectangular frame shape in plan view is provided around the product area (outside the broken line in the same figure).
As illustrated, the insulating substrate 2 is held in a vertical posture by inserting its four sides or three sides into the recessed groove 29 between the pair of vertical pieces 28 of the holding member 27 made of metal. A plurality of conductive jigs 23 are in contact with the surface 3 of the ear 6 on which the underlying metal layer (7) is formed. The conduction jig 23 includes a spring portion 24 having an inverted V-shape in a side view, and a needle portion 25 horizontally extending from the tip end of the spring portion 24. In a state in which the needle-like portion 25 is in contact with the insulating substrate 2, a plating process described later is performed.

On the other hand, as shown in FIG. 1 (B), the four sides or three sides of the same insulating substrate 2 as described above may be held by a plurality of conductive jigs 30. The conduction jig 30 includes a base portion 31 and a pair of elastic spring portions 32 that extend symmetrically from the base portion 31, and the pair of left and right needle-like portions 25 are connected to each other from the tip of the spring portion 32. It extends to approach. In a state where the needle-like portion 25 is in contact with both the front surface 3 and the back surface 4 of the insulating substrate 2 and the insulating substrate 2 is held, a plating process described later may be performed. The conduction jig 30 serves both as a holding means for the insulating substrate 2 and a feeding means for the insulating substrate 2.
Further, only the upper side of the insulating substrate 2 is held in a vertical posture by the plurality of holding jigs 30, and for each of the left and right side sides of the insulating substrate 2, as shown in FIG. The plating step described later may be performed in a state in which a plurality of conductive jigs 33 electrically connecting between the underlying metal layers (7) formed on the front surface 3 and the back surface 4 are sandwiched.

The conductive jig 33 has a C-shaped base 34 and a pair of elastic spring portions 35 extending symmetrically from the base 34, and the insulating substrate 2 is provided on each of the tip sides of the spring portions 35. A pair of needle-like parts 25 in contact with the front surface 3 and the back surface 4 are separately provided.
The conductive jig 33 is held by the holding member 27 and the insulating substrate 2 is in contact with the needle-like portion 25 of the conductive jig 23 on the surface 3 side on the upper side. The left and right side sides and the lower side in 2 may be clipped.

Hereinafter, a method of manufacturing the wiring board 1 according to the present invention will be described in the case of using the conduction jig 23.
As shown in FIG. 2 (A) in advance, it is insulating and is made of alumina and has insulating surfaces 3 and back surfaces 4, side surfaces 5 located on these four sides, and ears 6 located on each side surface 5 side. Substrate 2 was prepared. Note that the illustrated side surface 5 is the upper side of the insulating substrate 2.
The insulating substrate 2 has a form obtained by firing a single layer green sheet (not shown), or an unfired via conductor and an inner layer wiring (neither is shown) formed on a plurality of green sheets. Are laminated and pressure-bonded, and then fired.

First, as shown in FIG. 2B, the base metal layer forming step of forming the base metal layer 7 having a thickness of about 5000 Å to 1 μm on the entire surface 3 of the insulating substrate 2 was performed. This process was performed by applying electroless copper plating to the whole of the surface 3. The above process may be performed by sputtering using copper as a deposition material.
Next, as shown in FIG. 2C, a photosensitive resin having a thickness of about 140 to 160 μm (for example, a photosensitive film of Hitachi Chemical Co., Ltd .: Photocast, etc.) with respect to the entire upper surface of the above-mentioned base metal layer 7 ) 8 to form. Furthermore, a resist layer forming step was performed, in which, for example, irradiation (exposure) of ultraviolet light and development (etching) were sequentially performed on the photosensitive resin 8.

  As a result, as shown in FIG. 2 (D) and FIG. 3 (a), a desired pattern is formed on the upper surface of the base metal layer 7 except the position where the metal layer 22 to be formed later is to be formed. A plurality of metal layer resist layers 9 having the above were formed. At the same time, on the upper surface of the base insulating layer 7 located on the surface 3 side of the ear portion 6, a plurality of conductive portion resist layers 10 having a ring shape in plan view are formed. The thickness t of the conductive portion resist layer 10 is 50 μm or more, and the inner side 11 of the conductive portion resist layer 10 is the base having a circular plan view whose inner diameter (diameter) in plan view is 3 mm or less. The metal layer 7 was exposed.

Next, as shown by the arrow in FIG. 3A, the needle-like portion 25 of the conduction jig 23 is brought into contact with the underlying metal layer 7 located on the inner side 11 of each of the conductive portion resist layers 10 ( Contact area: 1 mm ² or less, for example, about 0.9 mm ² ).
In this state, the insulating substrate 2 is immersed in the electrolytic plating solution (not shown) together with the conductive portion resist layer 10, and the needle portion 25 of the conductive jig 23 is used to plate the upper surface of the base metal layer 7. A plating process was performed to apply electrolytic copper plating to supply current.
As a result, as shown in FIG. 3B, the metal layer 19 made of copper is substantially uniform over the entire top surface of the base metal layer 7 excluding the metal layer resist layer 9 and the conductive portion resist layer 10. It was formed with a certain thickness. During this time, the tip of the needle-like portion 25 of the conduction jig 23 is in contact with the upper surface of the base metal layer 7 surrounded by the conductive portion resist layer 10 with a small contact area of 1 mm ² or less. The deviation of the direction was suppressed within the range of less than 3 mm at the maximum.

Furthermore, on the surface 3 of the insulating substrate 2 from which the conduction jig 23 was removed, a resist layer peeling step was performed in which an etching solution (for example, an aqueous solution of sodium carbonate) was brought into contact. As a result, as shown in FIG. 3C, the metal layer resist layer 9 and the conductive portion resist layer 10 were peeled off from the base metal layer 7 and the metal layer 19 of the surface 3. At the same time, concave portions 20 and 21 having a predetermined shape in which the base layer 7 is exposed are formed on the bottom surface of these marks. In the metal layer 19 of the ear portion 6, there is left an elongated reverse conical recess 26 of a trace of the needle-like portion 25 of the conduction jig 23.
Then, an etching solution (for example, Meltex Co., Ltd. product: Enstrip S, etc.) is brought into contact with the surface metal of the metal layer 19 and the underlying metal layer 7 located on the bottoms of the recesses 20 and 21 Alternatively, an etching process is performed.

As a result, as shown in FIG. 3D, the surface metal of the metal layer 19 and the base metal layer 7 located on the bottoms of the recesses 20 and 21 were removed with a substantially uniform thickness. At the same time, a metal layer 22 of a desired pattern made of copper is formed in the product region on the surface 3 side of the insulating substrate 2, and in the metal layer 22 on the surface 3 side of the ear portion 6, the plan view is The annular surface 3 following the conductive layer resist layer 10 was exposed.
The wiring board 1 shown in FIG. 3D was obtained by the above manufacturing method.
In addition, after covering the surface of the metal layer 22 with a nickel film and a gold film for rust prevention by electrolytic plating or electroless plating, the ear portion 6 may be removed along the broken line.

In the method of manufacturing the wiring board 1 described above, in the plating step, the needle-like portion 25 of the conduction jig 23 is in contact with the upper surface of the base metal layer 7 surrounded by the conduction portion resist layer 10. Therefore, the conduction jig 23 does not move excessively from the insulating substrate 2 and the conduction jig 23 does not fall off even when subjected to pressure or the like due to the flow of a plating solution during the plating process. The required electrolytic copper plating could be performed reliably.
Further, in the plating step, the needle-like portion 25 of the conduction jig 23 can supply power to the base metal layer 7 of the insulating substrate 2 with a relatively small contact area, and is electrically connected to the wiring substrate 1 after the plating step. Since the situation where the jig 23 was integrated with the jig 23 can be prevented, and the conduction jig 23 can be easily removed from the wiring board 1, the processing efficiency of the plating step can be enhanced.
Therefore, according to the method of manufacturing the wiring board 1, it was confirmed that the effects (1) and (2) can be obtained.

In the resist layer forming step, instead of the conductive portion resist layer 10, as shown in FIG. 4A, the conductive portion resist exhibits an oval (annular) shape in plan view and has a thickness of 50 μm or more. The layer 12 may be formed. The conductive resist layer 12 has an oblong inner side 13 which is similar to the outer shape thereof. The major diameter of the inner side 13 is 3 mm or less, and on the upper surface of the insulating substrate 2 surrounded by the conductive resist layer 12, the underlying metal layer 7 with which the needle portion 25 of the conductive jig 23 contacts is exposed. ing. On the base metal layer 7, the deviation in the radial direction is only permitted in the range of less than 3 mm at most at the tip of the needle-like portion 25.
The conductive layer resist layer 12 may have an elliptical shape in plan view and an inner side similar to the elliptical shape having a major axis of 3 mm or less.

Furthermore, in place of the conductive layer resist layers 10 and 12, as shown in FIG. 4B, a conductive portion resist layer 14 having a U shape in plan view and a thickness of 50 μm or more may be formed. good. The conductive resist layer 14 has an inner side 15 whose outer shape in plan view is U-shaped and whose left and right (longitudinal) directions are 3 mm or less. The opening portion of the inner side 15 is opened at the center side (opposite to the side surface 5) of the surface 3 of the insulating substrate 2. Thus, it is possible to prevent the conductive jig 23 from being shifted excessively from the insulating substrate 2 or inadvertently falling off when the tip of the needle-like portion 25 comes out from the opening of the inner side 15. .
The conductive layer resist layer 14 may have a U-shape (channel shape or U-shape) in a plan view.

In addition, as shown in FIG. 4C, the conductive layer resist layer 16 may have a C-shape in plan view and a thickness of 50 μm or more, as shown in FIG. 4C. The conductive layer resist layer 16 has an inner side 17 having an arc shape in plan view that approximates a substantially circular shape through a narrow opening 18 in a part of a circle (ring shape, annular shape) in plan view. ing. The diameter (inner diameter) of the inner side 17 is also 3 mm or less.
The opening 18 does not have to open on the side 5 side of the insulating substrate 2 as shown in the drawing, and for example, the opening 18 may be opened on the center side of the surface 3 of the insulating substrate 2 . It is also possible to easily insert the needle-like portion 25 of the conduction jig 23 into the inner side 17 of the resist layer 16 through the opening 18 shown.
The openings 18 may be provided in a pair symmetrically in the vertical direction in FIG. 4 (C).
Alternatively, the opening 18 may be provided in part of the conductive portion resist layer 12 having an oval shape in plan view or the conductive portion resist layer having an elliptical shape in plan view.

The present invention is not limited to the embodiment described above.
For example, the respective steps are sequentially performed on both the front surface 3 and the back surface 4 of the insulating substrate 2, and in the plating step, a plurality of the conduction jigs 30 are used to form the front surface 3 and the back surface 4. A wiring board (1) having the metal layers 22 of different patterns may be manufactured.
In addition to the conduction jig 30, a plurality of the conduction jigs 33 may be used in combination.

Furthermore, the annular conductive resist layer 10 has a rectangular (square or rectangular) shape, a regular polygon with pentagon or more, or a deformed polygon in plan view, and each has a shape similar to the outer shape or the inner shape. It is good also as a form which has an inner side.
In addition, in the plating step, by performing electrolytic silver plating, a wiring substrate (1) in which a metal layer having a desired pattern made of silver is formed on at least one of the front surface 3 and the back surface 4 may be manufactured. .

  According to the present invention, even if the contact area of the conductive contact is reduced, the plating jig does not shift or fall off from the insulating substrate for plating, and a desired metal layer is formed on the surface of the insulating substrate. It is possible to reliably provide a method for manufacturing a wiring board that can be used.

1 …………………………… Wiring board 2 …………………………… Insulating board 3 ……………………………… Surface 4 …………………… ......... Back side (front side)
7... Base metal layer 9 ........................ Resist layer for metal layer 10, 12, 14, 16... Resist layer for conductive part 19, 22. ... Metal layer 23, 30, 33 .......... Conducting jig 25 .......... Needle-like part t ........................ Resist layer for conducting part Thickness of

Claims (4)

A method of manufacturing a wiring substrate, comprising forming a metal layer of a desired pattern on at least one of the insulating substrates comprising an insulating material and having a pair of opposed surfaces,
A base metal layer forming step of forming a base metal layer on the entire surface of the insulating substrate;
A metal layer resist layer for forming the metal layer on the upper surface of the base metal layer except for the position where the metal layer is to be formed among the upper surface of the base metal layer, an annular U-shape in plan view Or a resist layer forming step of forming a C-shaped conductive portion resist layer;
A conductive jig is brought into contact with the upper surface of the base metal layer surrounded by the conductive portion resist layer, current is supplied to the base metal layer through the conductive jig, and the insulation is formed in a predetermined electrolytic plating solution. And D. a plating step of depositing a metal layer by electrolytic metal plating on the upper surface of the base metal layer not covered with the resist layer for metal layer and the resist layer for conductive part by immersing the substrate.
A method of manufacturing a wiring board characterized by After the plating step, a resist layer peeling step for peeling off and removing the metal layer resist layer and the conductive portion resist layer; an etching step for removing the base metal layer not covered with the metal layer; have,
The method for manufacturing a wiring board according to claim 1. The conductive part resist layer has a thickness of at least 50 μm or more.
The method for manufacturing a wiring board according to claim 1, wherein: The plating step has a single needle-like portion pressed by the elasticity of the base end on the upper surface of the base metal layer formed on one surface of the insulating substrate, or formed on both surfaces of the insulating substrate Using the conductive jig having a pair of symmetrical needle-like portions individually contacting the upper surface of each of the formed underlying metal layers,
A method of manufacturing a wiring board according to any one of claims 1 to 3, wherein the method comprises:

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