JPS6149492A - Printed thick film fine pattern conductor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a printed thick film fine pattern conductor that is applied to, for example, a small sheet-like coil and has a high density and high reliability.

[Conventional technology]

Thick-film fine-pattern conductors are required in fields such as small coils and high-density wiring where relatively large current values are required. For example, a wire winding method is normally used to manufacture coils, but this method makes it difficult to manufacture small coils and causes variations in the state of the windings. Also, so-called printed coils made by etching copper foil with a thickness of 35 μm cannot obtain fine turns due to side etching, and only 2 to 3
It is difficult to produce small coils even with this method, as only a few turns can be obtained. However, in recent years, as motors have become smaller, there has been a demand for the development of fine coils having 3 to 20 fine turns per coil.

The present inventors have previously proposed several types of manufacturing methods for fine thick film printed circuit boards, as shown in Japanese Patent Application Laid-open Nos. 57-91590 and 170589 to 170591, among which several described the possibility of laminating printed circuit boards. In that case, to electrically connect each layer,
It is necessary to form a so-called through hole. Conventionally, through-hole formation methods include a method using rivets, a method of injecting conductive paste into the hole, a method of injecting solder into the hole, or an electroless plating method inside the hole. A method has been used in which electrolytic plating is performed after forming a conductor.

However, when considering the case where conductors are contacted through an extremely thin insulating layer with a thickness of 5 to 200 μm, the method using rivets increases the thickness of the g It's difficult to give sex. The method of injecting the paste has problems in making the thickness of the through-hole portion uniform, and also has problems in terms of reliability. Furthermore, it is difficult to make the thickness uniform with the method of injecting solder, and it is necessary to improve the heat resistance of the insulating layer. According to the electroless Metsky electrolytic plating method, uniform -
It becomes possible to fabricate a through hole with a conductor thickness of In this case, conductors and patterns on the substrate surface are generally formed simultaneously by electrolytic plating.

[Problem to be solved by the invention] When a through hole is formed by electroplating, the reliability of the through hole is closely related to the thickness of the conductor on the inner wall of the hole. However, since the conductor pattern is plated on the board at the same time as the conductor on the inner wall, if the conductor has a fine/o-turn, if the inner wall of the through hole is too thick, there will be electricity between the conductor patterns. A short circuit will occur.

Therefore, this invention has a highly reliable through hole,
Moreover, it is an object of the present invention to provide a glint thick film fine pattern conductor with high wiring density.

[Means to solve the problem]

According to this invention, fine thick film conductor e-turns are formed on both sides or one side of an insulating substrate, and the conductor wiring density is 3 or more per body and the conductor film thickness is 30 μm or more, and /(conductor wiring pitch) is 0045~
10'. If this ratio is smaller than 0.045, high reliability of the through hole cannot be obtained, and the heat cycle test often leads to disconnection. If the ratio is larger than 10, the A short circuit occurs. In order to obtain even more reliable results, this ratio should be 0075~7.
, more preferably 019-5.

The thick film microstructure of the present invention is manufactured, for example, as follows.

That is, a conductor is formed on a thin metal plate in areas other than the fine pattern area where the resist is to be obtained, and is electrolytically plated on the fine turn part using the metal thin plate as a cathode. is formed, and then the obtained conductor is adhered to the surface of the insulating substrate. A conductor is similarly attached to the other surface of the insulating substrate. In this respect, it is not necessary to include particularly fine E-turns, but it is necessary to include at least a conductor in the through-hole land portion. Next, a hole is made in the through-hole land, a catalyst is attached to the inner wall of the hole, a thin metal plate is removed by etching, and electroless plating is applied to the inner wall of the through-hole, followed by electrolytic plating. This electrolytic plating increases the conductor thickness on the inner wall of the through hole, and also increases the conductor thickness of the conductor/gut on the substrate. The wiring density of the conductor/gutern is 3 wires/■ or more, especially 5 wires/Wan or more, and the conductor thickness is 30 μm or more, especially 40 μm or more, and furthermore 70 μm or more.

In the above method, first, a conductor/gut on a thin metal plate is pasted onto an insulating substrate, and the thin metal plate is removed by etching to form a conductor/gut on the insulating substrate. However, other methods are also possible. For example, thickness 5μ
A method is to form a thin metal plate with a thickness of 35 μm on both sides of an insulating substrate and then form a conductive pattern by etching, or to form a conductive pattern on the insulating substrate by electroless plating or vapor deposition. There are methods. However, in the above-mentioned method, it is easy to form a fine and thick conductor pattern by lenost formation and electrolytic plating. ? This is the optimal method when a thicker conductor film is preferred. The details of this method are as follows.

The thin metal plate to be used may be one that is a conductor and can be etched, but preferably one that has etching characteristics different from those of electroplated conductors; in this case, when removing the thin metal plate by etching, Electrolytically plated conductors are not etched, allowing highly accurate etching of thin metal plates. Suitable sheet metals include aluminum, tin, and zinc. The film thickness is 1 to 500 μm, especially 5 to 200 μm, and even 10
A preferable range is 100 μm. A film thickness of 1 μm or less is difficult to handle and tends to cause unevenness in the plating film thickness. Further, if the film thickness is 500 μm or more, it takes time to remove the film by etching, and productivity decreases.

As a method of forming resist on the parts other than the pattern part on this thin metal plate, it may be formed by screen printing or gravure printing, but it is preferably formed using photorenost, which can easily obtain fine patterns. is preferable. As for its formation method, it can be obtained through coating, exposure, and development processes. Photorenosts include Eastman Kodak's KPR, KOR, KPL, and K.
TFR, KMER.

Tokyo Ohkasha's TPR, 0MR81, Fuji Pharmaceutical's FS
Negatives such as R, and Eastman Kodak KA
There are positive types such as DH and AZ-1350 manufactured by Sisolet, but those with excellent plating resistance are preferred, and negative types are particularly preferably used. A dry film resist can also be used. The thicker the resist film is, the more useful it is in preventing thick plating, but if the resist is too thick, it becomes difficult to obtain a fine pattern and the resist film is preferably 01 to 50 μm, particularly 1 to 10 μm. If the thickness is less than 0.01 μm, pinholes are likely to occur.

Any type of electrolytic plating may be used as long as it is a conductor, but silver, gold, copper, nickel, tin, etc. are preferred, and copper is particularly preferred from the standpoint of conductivity and economy. Examples of copper electrolytic plating include copper cyanide plating, copper pyrophosphate plating, copper sulfate plating, and borofluoride steel plating, and copper pyrophosphate plating is particularly preferred. When electrolytically plating fine patterns, the important factor is that the cathode current density is υ.If the cathode current density is small, the film becomes thicker in the width direction than in the thickness direction, and the cathode current density is 3 A/dm.
2 or more, especially 5 A/dm2 or more, even 8 A,'d
m" or more is preferable, and increasing the cathode current density suppresses thickening in the width direction. The higher the cathode current density, the better the size, and pulse plating is also preferably used. The upper limit of the cathode current density is determined by desperation. and 50 A/dm
2 or less is preferable. Electrolytic plating film thickness is 15μm
Although the above is a preferable range, this method is particularly effective when the electrolytic plating film thickness is thick, and is 20 μm or more, or even 3 μm thick.
It is particularly suitable for electrolytic plating of a film thickness of 5 μm or more. Further, it is preferable that the conductor wiring density is 3 wires/leap or more, particularly 5 wires/leaf or more.

As the insulating substrate used in this method, a film substrate, a laminated substrate, a glass substrate, a ceramic substrate, a metal substrate coated with an insulating layer, etc. can be used, and a film substrate is particularly preferred. All film substrates can be used, such as polyester film, epoxy film, polyimide film, polyparanoginate film, and triazine film. Preferred are phosphoric acid film and triazine film. The thickness of the film-like insulating substrate is preferably as thin as possible in the sense of high density, but if it is too thin, workability will be poor, so the film thickness should be 5 to 200 μm, especially 10 to 150 μm.
The preferred range of μm1 is 10 to 100 μm.

As a method for attaching a metal thin plate masked with a resist and subjected to electrolytic plating to the above-mentioned insulating substrate with the metal thin plate facing upward, a method of thermocompression bonding using an adhesive is preferably used. Further, when an adhesive is used, an insulating substrate is not particularly used, and the adhesive may simply be applied onto the electrolytic plating layer, or they may be directly bonded together.

Adhesives include polyester-isocyanate, phenolic resin-butyral, phenolic resin-nitrile rubber, epoxy-nylon, epoxy-triru rubber, acrylic resin, etc., and are heat resistant, moisture resistant,
Adhesives with excellent adhesive properties are preferred, and epoxy and phenol resin adhesives are particularly preferred. The film thickness of the adhesive is 1 to 200 μm, especially 2 to 1 μm, from the viewpoint of high density and adhesive properties.
A preferred range is 00 μm.

Next, the through-holes may be formed by any method as long as no particles or debris are generated and the conductor layer around the holes does not peel off from the insulating layer, such as using a drill or punch.

In the activation process for electroless plating, a normal activator for electroless plating is used, but when the metal sheet is aluminum, zinc, or tin, a normal activator cannot be used and If the metal thin plate is eluted and the bath is significantly deteriorated, or if the metal thin plate is completely eluted and the parts other than the conductor of the circuit part are not activated, the bath should be kept in a neutral region, pH = 4.
~10, especially those that can be controlled at pH = 5 to 95 are used.

Things that can be used for this include organic complexes of Tucladium, such as Schering's Activator Neogant 834 as an activating solution, and as a reducing solution,
Schering Co. Glueducer (Neogun) WA can be used by adjusting the pH with sulfuric acid and phosphoric acid, respectively. In addition, pre-treatment for activation includes a degreasing process using a surface activator to remove dirt from the thin metal plate or the inner wall of the through hole, and electroless plating on the rough surface to improve the adhesion of the deposited metal. Therefore, it is better to provide a soft etching process consisting of an aqueous ammonium persulfate solution.

As for the type of electroless plating, copper is preferred in terms of conductivity and economy, but any conductive material such as nickel, silver, or gold may be used. If the metal sheet is aluminum, zinc, or tin,
Metal thin plate removal → Normal electroless plating solution can be used if the electroless plating process is used, but in the case of electroless plating process, an electroless plating solution with a pH of -4 to 10 is used in the neutral range. There is a need to. Examples of these include Chive'r #, (7) Shoe 7-8-680 manufactured by Nippon Kanigen Co., Ltd., and the like.

As a method for removing the thin metal plate by etching, a method of etching by spraying or dipping using a solution that dissolves the used thin metal plate is used. Further, when aluminum, tin, or sub-metal is used as the metal thin plate, it is preferable not to etch the electrolytically plated conductor, but to etch it with an alkaline aqueous solution, for example.

Next, electrolytic plating is performed in the same manner as described above, but at this time, (through-hole conductor thickness) / (conductor wiring pitch)
Adjust the ratio so that it is 0045-10.

EXAMPLES Below, embodiments of the present invention will be described in order to further clarify aspects thereof, but the present invention is not limited to the following embodiments, and various modifications are possible.

"Example 1" After drying a negative resist "Microrenostore 47-11'Ocst j" manufactured by Eastmango Duck Co., Ltd. on a thin aluminum plate (thin metal plate) with a film thickness of 40 μm, a film thickness of 5 μm was applied.
Coating to a thickness of μm, pre-baking, exposing with a direct pressure mercury lamp through a circuit pattern mask, developing using a special developer and rinsing solution, and post-baking to form lenost on parts other than the circuit area. did.

Next, using a copper birophosphate plating solution manufactured by Vershaw Gyoda Co., Ltd., using a thin aluminum plate as a cathode, the current density was initially 0.
After steel plating to an average film thickness of 2 μm at 5 A/dm2, the current density was increased to 8 A7 dm2 to form a total of 200 μm thick copper on the circuit. After that 1, apply phenol resin-nitrile rubber adhesive r manufactured by Bostic Co., Ltd. to both sides of the polyimide film “Kashiton” (film thickness 25 μm) manufactured by DuPont Company.
An insulating substrate coated with XA 564-4J to a dry film thickness of 5 μm was electrolytically plated on both sides, and the thin aluminum plate was placed on the outside.
It was attached by thermocompression bonding at .degree. C. for 30 minutes, and then a hole of 0.70 renφ was drilled in the through hole forming part. After that, the activating liquid activator Neogant 834 manufactured by Schering Co., Ltd., which had already undergone pH adjustment, and the reducing liquid reducer.
The aluminum sheet was activated using NEOGAN WA, and then etched away using a solution prepared by diluting 36% hydrochloric acid with water at a ratio of 2:3. After that, electroless copper plating (MK-430 manufactured by Muromachi Chemical Co., Ltd.) was performed, and then a current density of 8A/
A printed thick-film fine-cut turn conductor is further coated with copper plating with a film thickness of 200 μm in dm2, with a wiring density of 5 lines/hole, and a conductor film thickness of 400 μm, with (4 body thickness of through hole part) / (conductor wiring pitch) = 2. I got it. As a result of conducting 300 cycles of heat cycle tests of 120°C for 1 hour and -60°C for 1 hour on 1000 of the above-mentioned through holes,
There were no wire breaks or cracks in the through-hole section.

"Example 2" A negative mold was applied onto a zinc thin plate (metal thin plate) with a film thickness of 50 μm using Sost "Micro Renostore 47" manufactured by Eastman Kodak.
-110cst J was dried, applied to a film thickness of 2 μm, baked, exposed through a circuit pattern mask with a high-pressure mercury lamp, developed using a special developer and rinse solution, and post-baked. Lennost was formed on parts other than the circuit part.

Next, using a copper pyrophosphate plating solution manufactured by Burnyo Gyoda Co., Ltd., using a thin zinc plate as a cathode, copper was plated to an average film thickness of 5 μm at an initial current density of IA/dm2, and then the current density was increased to 5 A/dm2.
dm2, and a total thickness of 50 μm of copper was formed in the circuit portion. After that, the conductive pattern surface was overcoated with an insulating film (Hitachi Chemical [WI-640)].
G-EPOEP-008 Using a poxy resin adhesive, two sheets are pasted together with the zinc thin sheet facing outside. Next, a hole with a diameter of 0.70 mm was drilled in the through hole forming part.

After that, activation treatment was performed using PH-adjusted activating liquid activator Neogant 834 (made by Schering Co., Ltd., reducing liquid Reducer Neogant) WA), and electroless nickel plating (Schumer S-680 made by Nippon Kanizen Co., Ltd.).
) was carried out. Thereafter, the thin zinc plate was removed by etching with a solution prepared by diluting 336 parts by weight of hydrochloric acid with water at a ratio of 2:3. Next, using a copper pyrophosphate plating solution manufactured by Barshaw Gyoda Co., Ltd., copper plating was further performed at a current density of 5 A/dm2 to a film thickness of 50 μm, resulting in a wiring density of 5 lines/diameter conductor film thickness of 100 μm (through-hole conductor thickness). A printed thick film fine pattern conductor having a pitch of /(wiring pitch) -0.25 was obtained. A heat cycle test of 120° C. for 1 hour and -60° C. for 1 hour was carried out for 300 cycles on 1000 of the above-mentioned through holes, and as a result, there were no disconnections or cracks.

“Example 3” Polyimide film “Kabton” manufactured by DuPont (film thickness 2
5μm), in the through-hole forming part, drill a 0.85mmφ hole by gunching, perform surface treatment,
Next, activating liquid activator manufactured by Schering Co.
Neogant 834, reducing liquid reducer Neogant) W
Activation treatment is performed using A, and then electroless copper plating (
MK-430 (manufactured by Muromachi Chemical Co., Ltd.) was applied so that the film thickness was 5 μm. Next, after drying, a negative resist "Microrenos"-110cstJ manufactured by Eastmango Duck Co., Ltd.
Pre-bake the coating so that the film thickness is 3 μm, and form the circuit i4.
It is exposed through a turn mask, developed using a special developer and rinse solution, and post-baked to form a resist on the circuit area.Then, the copper parts other than the pattern are coated with a ferric chloride solution and treated. Then, remove the resist strip 7'rJ-1 manufactured by Industrial Laboratories Co., Ltd.
Resist stripping was performed using 0OJ liquid. Then,
Copper plating with a film thickness of 245 μm was performed using a birophosphate copper plating solution manufactured by Barshaw Gyoda Co., Ltd. at a current density of 10 A/2, a wiring density of 5 lines/mm, a conductor film thickness of 250 μm,
A printed thick film machine-7 thin pattern 7/conductor having a ratio of (through-hole conductor thickness)/(wiring pitch) -4 was obtained. 12
A heat cycle test of 1 hour at 0° C. and 1 hour at -60° C. was carried out for 300 cycles on 1000 of the above-mentioned through holes, and as a result, there were no disconnections or cracks.

“Example 4” A negative resist manufactured by Eastmango Duck [Microresist 747-
After drying 110 cst J, apply it to a film thickness of 5 μm, bake it, expose it to a high-pressure mercury lamp through a circuit pattern mask, develop it using a special developer and rinse solution, and post-bake it. A resist was formed on parts other than the circuit part. Next, using a copper pyrophosphate plating solution manufactured by Barshaw Gyoda Co., Ltd., using a thin aluminum plate as a cathode, the average film thickness was 05 μm at an initial current density of 0.1 A/dm2.
After copper plating, increase the current density to 8A/dm2,
A 100 μm thick copper was formed on the circuit portion. After that, the conductive and J-turn surfaces were overcoated with an insulating face (WI-640 manufactured by Hitachi Chemical Co., Ltd.), and 5G-EPOEP-0 manufactured by Cemedine Co., Ltd.
Using 08-Pokin resin adhesive, attach two thin aluminum plates together with the aluminum sheets on the outside.

Next, a hole of 15 reduced diameter was drilled in the through-hole forming part. Thereafter, the tin plate was activated using pH-adjusted activating liquid activator Neogant 834 and reducing liquid Redacer Neogant 834 (manufactured by Nieling), and then the thin tin plate was treated with 5 parts by weight of sodium hydroxide aqueous solution. Removed by etching. After that, electroless copper plating (MK-430 manufactured by Muromachi Chemical Co., Ltd.) was performed, and then a current density of 8 A/dm2 was applied using a birophosphate steel plating solution manufactured by Barshaw Gyoda Co., Ltd.
Copper plating with a film thickness of 100 μm was carried out with a wiring density of 10 (
A printed thick film fine pattern conductor was obtained with a conductor thickness of 200 μm and a conductor thickness of through-hole portion/(wiring pitch) of −2.5. 120℃, 1 hour and 160℃
℃, 1 hour heat cycle test, 300 cycles,
As a result of testing 1000 of the above-mentioned through-holes, there were no disconnections or cracks.

"Comparative Example 1" In Example 4 described above, after electroless copper plating, electrolytic copper plating was performed so that (through-hole conductor thickness)/(wiring pitch) = 0.03. Obtained through hole 1
As a result of conducting a heat cycle test of 300 cycles at 120°C for 1 hour and -60°C for 1 hour on 000 pieces, 20 pieces were broken and 60 pieces were cracked.

"Comparative Example 2" In Example 4, after electroless steel plating, electrolytic copper plating was performed so that the ratio of (through-hole conductor thickness)/(wiring pitch) -15 resulted in a short circuit between the conductor wires. occured.

〔Effect of the invention〕

According to the present invention, a printed thick film fine pattern conductor having through holes with high reliability can be obtained, and in practical use, small coils with low resistance values, high density wiring, etc. can be provided with high performance.

Claims (1)

[Claims] (1) A through hole that has a conductor with a conductor wiring density of 3 lines/mm or more and a conductor film thickness of 30 μm or more on both sides or one side of an insulating substrate, and that electrically connects the conductor between the two sides. A printed thick film fine pattern conductor, characterized in that the ratio of the conductor thickness of the through hole portion to the pitch of the conductor wiring is 0.045 to 10.