JPH11198336A - Screen plate production method and wiring board - Google Patents

Abstract

(57) [Abstract] [Problem] To produce a screen plate and a wiring board without disconnection, chipping, or bleeding by printing with a printed wiring width of 50 μm or less. The plastic film (13) has Ni or
A mesh (6) is formed with a Ni-Co plating film, a screen plate is manufactured, and a wiring substrate is manufactured by performing printing on a ceramic substrate wafer or a polyimide flexible substrate without disconnection, chipping, and printing bleeding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen plate and a wiring board for forming a pattern by a screen printing method.

[0002]

2. Description of the Related Art A metal mask for screen printing is a suspended metal mask in which a stencil (print pattern) formed by electroforming a stainless steel mesh formed in advance and a solid metal mask in which a mesh and a stencil are formed by electroforming or etching. Masks were developed in the 1970's.

At present, the suspended metal mask is used for some high-precision printing as described in Electronic Materials, May, 1989, pages P20 and P79. However, at the present time, when the wiring width is 50 μm or less, the printed film thickness is required to be improved, and a printed pattern requiring oblique wiring is also required. On the other hand, solid metal masks
Since the mesh is easily broken at a high price, it is practically used for printing a solder paste that does not require a mesh and has a simple pattern.

[0004]

In screen printing, as shown in FIG. 2, a printing material 2 is fixed to a printing table 1 of a printing press, and the printed material and a screen plate 3 are fixed with a gap 1 to 3 therebetween. With the paste 4 placed on the screen plate, the squeegee 5 is moved in the direction a to extrude the paste from the mesh to form a desired pattern. The screen plate used for such printing is a screen plate having a cross-sectional shape of A and B shown in FIG.
As shown in FIG. 5, a mesh having a wire diameter of 30 to 50 μm crosses the printed pattern 8, and in a printed pattern having a line width of 50 μm or less, the conductor 9 printed as shown in FIG.
In this case, a disconnection 11 and a slight chipping (12) occur.

[0005] Further, there is a problem that the line width is widened by bleeding 10 as shown in FIG. The screen plate is manufactured by electrohoming and etching. However, when forming a fine line of 50 μm or less, it is difficult to etch, and in electrohoming, the edge becomes round due to side spearing, so that the plating thickness cannot be increased. In order to increase the thickness, a plating thickness of the printed pattern portion is required to be 30 to 100 μm, and a new screen is required.

An object of the present invention is to laser-process a plastic film capable of sharpening an edge portion of a printing pattern in order to easily produce a screen plate for printing a thick film with a printing line width of 50 μm or less. In order to improve the printing shape, a thin mesh corresponding to the printing pattern is formed of a Ni plating film that is difficult to break. In addition, in order to produce a screen plate more easily, a Ni foil on which a mesh is formed in advance is bonded to a plastic with an adhesive, and then a printing pattern is formed with a laser beam. Another object of the present invention is to provide a wiring board printed on a Si wafer or a flexible substrate (polyimide film) in addition to a ceramic plate or a green sheet (a raw ceramic sheet before firing).

[0007]

According to the screen plate of the present invention, a printing pattern portion is formed by a plastic film and a mesh pattern portion is formed by Ni plating to increase the thickness of the printing pattern portion and sharpen an edge portion. . In addition, in order to facilitate the production, a foil in which a mesh is formed in advance is produced, and a printing pattern is formed by laser processing after adhering to a plastic film with an adhesive. In addition, a soft plastic film is used on the surface to be printed to cope with a print-prone material that tends to cause bleeding, such as printing on a Si wafer or a polyimide film.

[0008]

(Embodiment 1) The present invention is shown in FIG.
(E). A surface 14 of a plastic film 13 (for example, polyethylene terephthalate or polyimide film) having a thickness of 30 to 50 μm is roughened by plasma or sandblasting, then etched with chromium-sulfuric acid, and then palladium chloride-tin chloride or the like. After the passivation, Ni of 0.2-1 μm thickness
Alternatively, electroless plating of Cu is performed.

(B) Next, a mesh and a printing pattern are formed with the plating resist 15. (C) Next, Ni or Ni-Co is 5 to 30 μm by electroplating
Plating to thickness. If the plating film thickness is 15 μm or less on the mesh side, mesh breakage occurs during printing,
If it is 50 μm or more, the flow of the paste can be prevented. On the printed pattern side, plating defects tend to occur at 5 μm or less, and at 10 μm or more, the edges of the printed pattern become rounded and a sharp edge cannot be obtained, and the printed pattern tends to bleed.

After the electroplating, the plating resist is removed or laser light is irradiated as it is, and the plating resist 15 is removed.
Then, the plastic film 13 is removed, and the print pattern 8 is formed.

As a result of printing the conductor paste on the ceramic and polyimide films using the screen slab thus produced, printing with a line width of 40 μm and a film thickness of 30 μm was completed. Although bleeding occurred in printing on the Si wafer, the printing pattern portion was formed with laser light without forming plating on the printing pattern side, and as a result, bleeding-free printing was possible on the Si wafer.

(Embodiment 2) As in Embodiment 1, FIG.
E). Electron beam vapor deposition of Cr—Cu to a thickness of 0.5 to 1 μm on the surface of a plastic film 13 having a thickness of 30 to 50 μm (14), followed by formation of a plating resist with a photoresist (15), followed by Ni or Ni—Co To 5
After electroplating 20μm (6,7), remove the plating resist after plating and do not etch Ni such as ammonium perchlorate, but use Cu etchant to etch Cu.
After removing the plastic, the plastic was removed by laser light to produce a screen version. With this screen plate, printing was performed on a green sheet, and good results were obtained.

(Embodiment 3) FIG. 1 (A, F, G, H)
Will be described. An epoxy-based, photo-curing, or heat-thick adhesive was applied or attached to a plastic film having a thickness of 30 to 50 μm (F (16)). A Ni or Ni-Co plating foil 6 having a mesh pattern formed in advance by an electrohoming method is adhered on the adhesive layer (16) using a roller or a hot press machine (G) and then adhered to the mesh pattern. Printed pattern 8 by removing plastic film with laser light
Was formed.

Using this screen plate, a conductive paste or a conductive adhesive was printed on a Si wafer and a polyimide film to prepare a wiring board. In this case, printing blur did not occur during printing up to a wiring pitch of 150 μm, a wiring width of 30 μm, and a film thickness of 12 to 20 μm. As in the first and second embodiments, no disconnection or chipping was observed in the oblique wiring portion as shown in FIG.

In the case of using the screen plate of the present invention, in Examples 1, 2 and 3, after Ni or Ni-Co is electroplated, the screen plate is once framed on a temporary frame larger than the screen plate, and then the screen plate is plated. Formally fixed and processed with laser light. In this case, the area to be plated may be the same size as the screen frame, or smaller than the screen frame when emphasizing dimensional accuracy.

Further, when the screen is framed, a prescribed tension is required for printing, and therefore, the dimension is 10 to 10 mm.
Since it extends 20 μm / 100 mm, an automatic framing apparatus equipped with four pattern recognition cameras was used to correct the dimensions in advance when creating the photomask or to keep the dimensions within the specified dimensions when framing.

[0017]

According to the present invention, even with a wiring width of 50 μm or less, printing with a thick print film and no breakage can be performed.
Further, fine wiring having a wiring pitch of 150 μm and a wiring width of 30 μm can be printed with high accuracy not only on a ceramic substrate but also on a Si wafer or a flexible substrate made of polyimide.

[Brief description of the drawings]

FIG. 1 is a process diagram of manufacturing a screen plate for explaining the present invention.

FIG. 2 is a schematic diagram illustrating screen printing.

FIG. 3 is a schematic view of a conventional screen plate.

FIG. 4 is a schematic cross-sectional view of a conventional screen plate.

FIG. 5 is a plan view of a printing substrate printed by a conventional screen plate.

FIG. 6 is a schematic plan view of a screen plate for explaining the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Printing stage, 2 ... Printed object, 3 ... Screen plate, 4 ... Paste, 5 ... Squeegee, 6 ... Mesh pattern layer, 7 ... Print pattern part (plating layer), 8 ... Print pattern part (part through which paste passes) ), 9 ...
Wiring conductor, 10: rainbow, 11: disconnection, 12: chipped, 1
3: plastic film, 14: thin film layer (electroless plating or electron beam evaporation layer), 15: plating resist,
16 ... adhesive layer.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masato Kirigaya 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture, Ltd.

Claims (4)

[Claims] 1. A step of roughening the surface of a plastic film, a step of electrolessly plating the roughened surface, a step of forming a mesh and a printing pattern with a photoresist, and then an electro-nickel plating, and a laser beam from the printing pattern side. A method for producing a screen printing plate, comprising: irradiating with a mask to remove a photoresist and a plastic film in a printing pattern portion. 2. A step of forming a metal thin film on the surface of a plastic film by electron beam evaporation, forming a mesh and a printing pattern with a photoresist to form a plating resist, and further performing an electric Ni plating to remove the photoresist. A method for producing a printing screen plate, comprising removing a plastic film from a printing pattern side using a laser beam. 3. A step of manufacturing a Ni foil having a mesh pattern formed in advance by an electrohoming method, a step of applying an adhesive to a plastic film and then bonding the Ni foil having a mesh pattern formed thereon, and a surface on which the mesh pattern is bonded. A method for producing a screen plate for printing, characterized in that plastic on a printing pattern portion is removed by a drawing device using a laser beam on the surface on the opposite side of the printing plate. 4. A wiring board produced by using a screen plate produced by the method according to claim 1.