JP2000151076A - Method of producing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure that processes such as etching and the like are property performed without dropping a metal plate used in a printed wiring board in carrying and variously processing the metal plate on a roller. SOLUTION: A method of producing a printed wiring board comprises the steps of connecting a guide plate 4 to the leading side of a substrate 1 in a carried direction, wherein the substrate 1 comprises a flexible metal plate 2 not thicker than 50 μm in the thickness direction and the guide plate 4 is more rigid than the substrate 1, and carrying the combination of the guide plate 4 and the substrate 1 on a plurality of rollers 8, 8. Since the guide plate 4 carries the substrate 1 in which dry films are stuck on both faces of the metal plate (foil) 2, in flexibility controlled state along the thickness direction, it is hard to flexibly deform when spraying etchant, developer or cleaning fluid in the thickness direction, and the substrate 1 fallen off between the rollers 8, 8 can be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board in which a thin substrate made of a flexible metal foil or the like is etched and conveyed on a plurality of rollers in an etching step or the like.

[0002]

2. Description of the Related Art A multilayer wiring board in which a conductive layer is formed between a plurality of insulating layers is manufactured by alternately laminating insulating layers and conductive layers on both surfaces of the insulating substrate. In order to reduce the size and density of such a wiring board, a thin metal plate (foil) is embedded in the insulating substrate at the center in the thickness direction and over substantially the entire surface. By embedding such a metal plate, required strength can be obtained even as a thin insulating substrate. In addition, the entire multilayer substrate does not warp against the stress generated during thermal curing when forming the resin insulating layer on each surface of the insulating substrate or the thermal stress generated due to the difference in thermal expansion between the resin insulating layer and the conductor layer. Like that.

The metal plate is made of copper, iron, nickel, aluminum, silver, or the like, and has a thickness of several tens μm.
Further, when embedded in the insulating substrate, through-hole conductors for conducting the conductive layers formed on both surfaces thereof are made to penetrate in a non-contact manner, so that through-holes for through-holes are formed in predetermined positions in advance by etching. You. In order to form such a through-hole, a photosensitive dry film having a thickness of several tens of μm made of an epoxy resin is attached to both surfaces of the metal plate,
The film is exposed and developed in a predetermined pattern. As a result, an etching resist is formed on the surface of the metal plate, exposing the position where the through hole is to be formed in the metal plate.
Next, the metal plate is etched.

As shown in FIG. 5A, a metal plate 40 having the etching resist formed on the surface thereof is transported on a plurality of transport rollers 42 from left to right in the figure. Also, a plurality of nozzles 44 vertically arranged above and below each roller 42 are provided.
From there, the etching liquid e is sprayed in a shower shape. During the transfer, a portion of the metal plate 40 not covered with the etching resist is etched and a through hole (not shown) for a through hole is formed. After that, when the etching resist is removed with a stripping solution, a metal plate 40 having a through hole at a predetermined position is obtained.

[0005]

When the metal plate 40 is etched, as shown in FIGS. 5B and 5C,
Since the metal plate 40 has a thickness of several tens of μm, the metal plate 40 is easily bent and may fall down from between the rollers 42 following the rotation of the rollers 42. Due to the falling off of the metal plate 40,
The efficiency of the etching process is reduced. Also, if the dropped metal plate 40 is bent or deformed,
It had to be discarded, resulting in a lower yield.
In addition, the similar falling off of the metal plate 40 occurred in other transporting steps such as a water washing step and a subsequent drying step.

According to the present invention, in various processes in which a substrate such as a metal plate used as a wiring substrate is etched while being conveyed on rollers, the processing such as etching can be properly performed without the substrate such as a metal plate falling off. It is an object of the present invention to provide a method of manufacturing a wiring board which can be performed in a short time.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has been conceived in that a substrate such as a thin metal plate is transported over a plurality of rollers in a state where the substrate is hardly bent. Things. That is, the method for manufacturing a wiring board according to the present invention includes connecting a lead plate having a higher rigidity than the substrate to at least the transported front side of the substrate that is easily bent in the thickness direction. The method is characterized in that the method includes a step of transporting a plurality of rollers integrally with the substrate.

According to this, the substrate made of a thin metal plate (foil) or the like is conveyed in a state in which the bending is suppressed by the leading plate, so that the etching liquid, the developing liquid, or the cleaning liquid is supplied from the thickness direction. Even if it is ejected, it is difficult to be deformed, and it is possible to reliably prevent the substrate from falling off from between the transport rollers. Therefore, when the substrate is a single metal plate or a substrate whose surface is made of metal, necessary etching, washing, drying, etc. can be appropriately performed. When a photosensitive resin is present on the surface of the substrate, development and roughening of the resin surface can be performed. In addition, it is possible to prevent a decrease in the productivity of the substrate. Note that the above steps include developing the substrate,
In addition to the steps such as etching, washing, and drying, the transport itself between these steps is also included. Further, the leading plate may be any one that is connected at least on the front side of the substrate to be conveyed and that has a size larger than the distance between adjacent rollers.

Further, the present invention also includes a method of manufacturing a wiring board, wherein the board is a metal plate having a thickness of 50 μm or less or a plate mainly composed of the metal plate. According to this, it is possible to provide a small and thin wiring board, which is buried in the insulating substrate to increase its strength and does not warp a wiring board using the same. The reason why the thickness of the metal plate (foil) is set to 50 μm or less is that a metal plate having a thickness exceeding this thickness has a small bending in the thickness direction and is less likely to fall off between the transport rollers. is there. On the other hand, the lower limit of the thickness of the metal plate is appropriately selected within a practical range, but is preferably 10 μm or more. If the thickness is less than 10 μm, the original purpose of the metal plate, which imparts rigidity to the entire multilayer wiring board, is hardly achieved. In addition, copper,
Aluminum, nickel, iron, chromium, molybdenum, or an alloy based on any of them, or amber having a low coefficient of thermal expansion (36 wt% Ni-Fe alloy), and copper coated on both surfaces of the amber, A clad plate in which molybdenum is coated with copper on both surfaces is also used.

[0010] The present invention also includes a method of manufacturing a wiring board, wherein an etching resist is formed on both surfaces of the metal plate of the substrate, and a predetermined position of the metal plate is etched during the transportation. As a result, the metal plate (foil) is formed by the injection pressure when the etching liquid is sprayed from the plurality of nozzles arranged on the both surfaces substantially orthogonally to the transfer direction of the metal plate along the transfer roller and by the roll of the transfer roller. A predetermined through hole or a concave portion can be reliably formed in a position exposed from between the etching resists without dropping. The etching resist has, for example, a predetermined pattern that exposes and develops a dry film or a coated photosensitive resin layer previously coated on both surfaces of a metal plate to expose a part of the metal plate. .

[0011]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B show a state of transport of a substrate 1 according to the present invention. The substrate 1 is shown in FIG.
As shown in FIG. 3C, a metal plate 2 made of a thin copper foil having a thickness of about 35 μm is provided with a dry film 3 made of a photosensitive resin having a thickness of about 10 μm attached to both surfaces thereof. The substrate 1 is transported from left to right on the plurality of transport rollers 8, 8,... As shown in FIGS. The substrate 1 is connected to the leading plate 4 via tapes 7, 7 on the leading side to be transported, that is, on the right side in the figure, and is transported integrally with the leading plate 4 on the transport rollers 8, 8,. Is done.

The leading plate 4 is made of a material having a higher rigidity than the substrate 1, for example, a composite material of bismaleimide triazine (BT) resin and glass fiber, has a plate thickness of about 0.8 mm and is substantially the same as the substrate 1. Have a size. However, the length of the leading plate 4 along the transport direction is at least always 2 as shown in the figure.
It is necessary that the size be located on one roller 8. Protrusions 6 and 6 having a length of about 3 cm protrude from the left side of the leading plate 4 on the side opposite to the transport direction, and an acid-resistant material is provided between each convex piece 6 and the front side of the substrate 1. For example, fluororesin
(Teflon, a product name of DuPont, USA) are attached. The reason why the tape 7 has acid resistance is that the metal plate 2 in the substrate 1 is formed as will be described later.
This is because when etching is performed, it is resistant to an acidic etchant.

The metal plate 2 is buried in the insulating substrate as a core material of the insulating substrate in a wiring board to be manufactured later, but a through-hole conductor for conducting between conductive layers formed on both surfaces of the insulating substrate is used. It is necessary to previously form a through hole for penetrating by contact. For this reason, as shown in FIG. 1 (C), a substrate 1 having the films 3 and 3 adhered to both sides of a metal plate 2 is formed. Keep it.

Next, as shown in FIG. 2 (A), the substrate 1 having the exposed film 3
8,... While being transported above, the upper and lower nozzles 9 that are substantially perpendicular to the transport direction
The developer g is sprayed in a shower shape. As a result, FIG.
As shown in FIG. 3, concave portions 3a, 3 are located at positions other than the positions exposed by the above-described exposure on each of the films 3, 3 (negative type).
a becomes the formed etching resist 3b, and the surface of the metal plate 2 is exposed at the bottom of each recess 3a. In such a developing step, the substrate 1 which is originally easily bent in the thickness direction is transported together with the guide plate 4 having higher rigidity over the rollers 8, 8,. Developing is performed with high accuracy.

Further, as shown in FIG. 2B, the developed substrate 1 is transported together with the leading plate 4 on rollers 8, 8,. An etching solution e containing ferric chloride or the like is sprayed from each of the upper and lower nozzles 9 that are substantially perpendicular to the above, to each of the etching resists 3b, 3b on both surfaces of the substrate 1 in a shower shape. As a result, as shown in FIG. 2B, the exposed portions of the metal plate 2 sandwiched between the recesses 3a, 3a are corroded and removed, and the through holes 2a penetrating the upper and lower surfaces are formed. Also in such an etching step, the substrate 1 which is originally easily bent in the thickness direction is transported together with the leading plate 4 having higher rigidity over the rollers 8, 8,. Without being dropped from the substrate, appropriate etching is performed and the through-hole 2a can be accurately formed.

Then, while carrying the etched substrate 1 together with the leading plate 4 on the rollers 8, 8,..., The substrate 1 is inserted into a washing section (not shown) and washed with pure water to remove the etchant adhering to the surface. I do. Thereafter, the substrate 1 is heated and dried while being transported on the rollers 8, 8,... Together with the leading plate 4.
In such a washing or drying step, the substrate 1 is transported without falling off between the transport rollers 8. FIG. 2C shows a part of a cross section of the metal plate (substrate) 2 from which the films 3 and 3 have been removed by contacting the substrate 1 with a stripping solution of an aqueous NaOH solution after the drying.

FIG. 3 relates to a method of manufacturing a wiring board using a metal plate 2 provided with a through hole 2a. First, as shown in FIG. 3A, prepregs 10a and 10b and copper foils 12a and 12b having a thickness of 12 μm are arranged on both surfaces of the metal plate 2. The prepregs 10a and 10b are made of a composite material in which continuous porous PTFE is impregnated with an epoxy resin. Next, a stainless steel (not shown) is formed outside the copper foils 12a and 12b.
It is sandwiched between upper and lower dies (not shown) via an insert plate made of 304). When vacuum heating press is performed by the upper and lower dies, the resin of the prepregs 10a and 10b is hardened to form resin insulating layers 11a and 11b, respectively, as shown in FIG. 3 (B). It is buried almost entirely in the center in the thickness direction. Further, the copper foils 12a and 12b also become the core substrate 10 integrally joined to the surfaces of the resin insulating layers 11a and 11b.

Next, the metal plate 2 and the insulating layers 11a, 11
As shown in FIG. 3 (C), the core substrate 10 formed by press-molding of the metal plate 2 and the copper foils 12a and 12b vertically penetrates the inside of the through hole 2a of the metal plate 2 as shown in FIG. Also, a small diameter through hole 11c is formed by laser processing. Further, a through-hole conductor 11d is formed in the through-hole 11c by copper plating. In addition, the through-hole conductor 1
The hollow portion inside 1d is filled with an epoxy resin or the like. Further, when etching or the like is performed on the copper foils 12a, 12b on the surface, the first conductor layers 14a, 14a,
14b is formed. The conductor layers 14a and 14b are electrically connected to each other via the through-hole conductor 11d.

Further, as shown in FIG.
A prepreg and a copper foil are respectively laminated on the a, 11b and the conductor layers 14a, 14b in the same manner as described above, and are sandwiched between upper and lower dies (not shown) via interposition plates. When vacuum heating press is performed by the upper and lower dies, the resin of the prepreg is hardened, and the resin insulating layer 1 is formed as shown in the figure.
5a and 15b. The second conductor layer 17 is formed by etching the copper foil or the like.

Incidentally, via holes are formed in the resin insulating layers 15a and 15b by laser processing, and the conductor layers 14a and 14b are formed.
The surface at the predetermined position b is exposed. Via conductors 16 are formed in the via holes by copper plating. The via conductor 1
6, the first conductor layer 14a and the second conductor layer 17 conduct with each other. In FIG. 3D, a similar via conductor and a second conductor layer (not shown) are formed below the resin insulating layer 15b.

Then, as shown in FIG. 3D, a solder resist layer 18 is formed on the resin insulating layer 15a, and the solder resist layer 18 is formed on the surface of the second conductor layer 17 by laser processing and copper plating. Solder bumps (terminals) 19 are formed to penetrate through 18. Further, a similar solder resist layer is formed below the lower insulating layer 15b, and a second solder resist layer (not shown) exposed from an opening provided therebetween.
The surface of the conductive layer is plated with Au and Ni to obtain a multilayer wiring board 20 used as a connection terminal.

In the process of manufacturing the wiring board 20, the metal plate 2 enhances the strength of the core substrate 10 and also forms the insulating layers 11a, 11b, 15a, 15b and the conductor layers 14a, 1b.
When the wiring board 4b is formed, the wiring board 20 is prevented from being warped later. Moreover, the metal plate 2 is
It can also be used as a ground or power supply pattern of a circuit in the wiring board 20 formed by a, 14b and the like.
When the metal plate 2 is used for grounding or the like, the core substrate 10
A via conductor (not shown) that conducts between the metal plate 2 and the conductor layer 14a or the like is formed at an appropriate position by laser processing and copper plating.

FIG. 4 relates to a leader plate of a different form.
(A) shows a leading plate 22 which conveys a plurality of rollers 8, 8,... Together with the substrate 1 or the metal plate 2. The leading plate 22 has a rectangular shape of substantially the same size as the substrate 1 and the like in plan view, and is provided with inclined portions 24, 24 chamfered at corners at both ends of a front side 23 to be conveyed. By forming the inclined portion 24, the transport rollers 8, 8 of the leading plate 22 itself are formed.
Smooth sliding on the top can be ensured. In addition, the leading plate 2
If a hollow portion 25 indicated by a dashed line is formed substantially at the center of 2, the drainage of an etching solution or the like in the etching or washing step can be facilitated. It should be noted that, instead of the hollow portion 25, the drainage can be easily performed by providing a water gradient in which the vicinity of the center of the upper surface of the leading plate 22 is slightly higher than the periphery.

Further, as shown in FIG. 4B, it is also possible to form a leading plate 26 having a substantially semicircular front side 28 to be conveyed, and to form a hollow portion 29 therein. Further, as shown in FIG. 4 (C), the leading plate 4 is formed in a rectangular frame shape, and a metal mesh screen 5 is stretched in a hollow portion inside thereof. Cutting can be facilitated.

On the other hand, as shown in FIG. 4 (D), together with a leading portion 32 connected via a tape 7 to the front side to which the substrate 1 or the metal plate 2 is transported, and transported from both sides of the leading portion 32. It is also possible to use a leading plate 30 integrally provided with a pair of side pieces 34, 34 extending in the opposite direction. Leader 32
And the substrate 1 in a rectangular recess 33 surrounded by a pair of side pieces 34.
Is inserted and connected by the tape 7, even if the etching liquid or the like is jetted while being conveyed on the conveying rollers 8, 8,..., The substrate 1 and the like are more difficult to bend, and the falling off thereof can be prevented more reliably.

As shown in FIG. 4 (E), the whole has a rectangular shape in plan view, and has a rectangular leading portion 37 near the front side to be conveyed and a rectangular hollow portion 38 near the rear side. It is also possible to use the leading plate 36. The hollow part 38
The substrate 1 or the metal plate 2 having a substantially similar shape is connected thereto via a tape 7 to be integrated, and is conveyed on the conveying rollers 8, 8,. Even if an etching solution or the like is sprayed during the transfer, the substrate 1 and the like are prevented from bending in the thickness direction because all of the four surroundings are connected to the highly rigid leading plate 36 via the tape 7. Therefore, an appropriate etching process or the like is performed without falling off between the rollers 8.

The present invention is not limited to the embodiments described above. For example, the material of the leading plate is not particularly limited, but in consideration of resistance to an etchant, phenol, epoxy, acrylic, polyethylene, polypropylene, polycarbonate, or the like, which is an acid-resistant resin, or any of these and glass fiber. A composite material may be used. Alternatively, it is also possible to apply a metal such as stainless steel or a titanium alloy having acid resistance, and further, a tempered glass or the like. Further, the material of the tape for connecting the leading plate and the substrate (metal plate) is not particularly limited, but a material mainly composed of a resin or a metal foil having acid resistance to withstand an etching solution is used.

Further, the steps to which the method of the present invention is applied include, in addition to the above-described steps, a step of etching the resin insulating layer into a predetermined pattern by development, and a step of subsequently applying a rinsing liquid. The wiring board to be used in the present invention is an insulating board 10 in which a metal plate 2 having at least a through hole 2a formed in the predetermined pattern is buried, and a conductive layer formed on the surface of the insulating board 10. It is not affected by the number of conductor layers provided therein, the presence or absence of terminals, electronic components, and the like on the main surface.

[0029]

According to the manufacturing method of the present invention described above, a substrate made of a thin and flexible metal plate or the like is connected to a leading plate and is integrally transported over a plurality of rollers. Even if an etching solution, cleaning water, or the like is sprayed, it can be reliably prevented from bending and dropping from between the rollers. Therefore, the processing efficiency of the substrate can be kept high and stably. Furthermore, since appropriate development and etching can be performed on the substrate, it is possible to increase the strength of the wiring substrate using the substrate and to manufacture the wiring substrate with improved shape and shape accuracy.

[Brief description of the drawings]

1 (A) and 1 (B) are perspective views or side views showing a transport state of a substrate according to the present invention, and FIG. 1 (C) is a dashed-dotted line portion C in FIG. 1 (B).
FIG.

2 (A) and 2 (B) are schematic diagrams showing each processing step of a substrate according to the present invention, and FIGS. 2 (a) and 2 (b) are enlargements of dashed lines a and b in FIGS. 2 (A) and 2 (B). Sectional drawing, (C) is a sectional view of the obtained metal plate.

FIGS. 3A to 3D are schematic cross-sectional views illustrating respective manufacturing steps of a wiring board according to the present invention.

4 (A) to 4 (E) are perspective views or plan views showing different forms of a lead plate used in the present invention.

FIGS. 5A to 5C are schematic views showing a substrate etching process according to a conventional technique.

[Explanation of symbols]

 1 ………………………………………………………………………………………… Metal plate 3 …………………… Dry film 3b ...... Etching resist 4,4 ', 22,26,30,36 Leading plate 8 ... Roller 20 ………………………… Wiring board

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E339 AA02 AB02 AD03 AD05 BE13 BE16 CC10 CD01 EE02 EE04 GG10 5E346 AA05 AA06 AA12 AA15 AA42 AA43 BB01 CC08 CC32 CC58 DD32 DD48 FF04 GG16 GG17 GG22 HH11 HH33

Claims (3)

[Claims] 1. A lead plate having a higher rigidity than the substrate is connected to at least a side of the substrate to be conveyed which is easily bent in the thickness direction, and the lead plate and the substrate are integrally formed. A method for manufacturing a wiring board, comprising a step of transporting the wiring board on a roller. 2. The method according to claim 1, wherein the substrate is a metal plate having a thickness of 50 μm or less or a plate mainly composed of the metal plate. 3. The method of manufacturing a wiring board according to claim 2, wherein an etching resist is formed on both surfaces of the metal plate, and a predetermined position of the metal plate is etched during the transportation. Method.