KR102044497B1 - Method for manufacturing flexible printed circuit board, and flexible printed circuit board manufactured by the method - Google Patents

Method for manufacturing flexible printed circuit board, and flexible printed circuit board manufactured by the method Download PDF

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Publication number
KR102044497B1
KR102044497B1 KR1020130011947A KR20130011947A KR102044497B1 KR 102044497 B1 KR102044497 B1 KR 102044497B1 KR 1020130011947 A KR1020130011947 A KR 1020130011947A KR 20130011947 A KR20130011947 A KR 20130011947A KR 102044497 B1 KR102044497 B1 KR 102044497B1
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KR
South Korea
Prior art keywords
flexible printed
circuit board
printed circuit
circuit pattern
bonding sheet
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Application number
KR1020130011947A
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Korean (ko)
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KR20140099395A (en
Inventor
권오정
유정상
허태현
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주식회사 아모그린텍
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Priority to KR1020130011947A priority Critical patent/KR102044497B1/en
Publication of KR20140099395A publication Critical patent/KR20140099395A/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/46—Manufacturing multilayer circuits
    • H05K3/4611—Manufacturing multilayer circuits by laminating two or more circuit boards
    • H05K3/4626—Manufacturing multilayer circuits by laminating two or more circuit boards characterised by the insulating layers or materials
    • H05K3/4629—Manufacturing multilayer circuits by laminating two or more circuit boards characterised by the insulating layers or materials laminating inorganic sheets comprising printed circuits, e.g. green ceramic sheets
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H05K1/0306—Inorganic insulating substrates, e.g. ceramic, glass
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/12—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
    • H05K3/1283—After-treatment of the printed patterns, e.g. sintering or curing methods
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/01—Dielectrics
    • H05K2201/0137—Materials
    • H05K2201/0154—Polyimide

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing Of Printed Wiring (AREA)

Abstract

The present invention relates to a method of manufacturing a flexible printed circuit board, and a flexible printed circuit board manufactured by the same. A method of preparing an alumina substrate 11 (S10) and a circuit using a conductive paste on the alumina substrate 11 are performed. After forming the pattern 13 (S20), sintering the alumina substrate 11 on which the circuit pattern 13 is formed at a temperature of 700 ~ 900 ℃ (S30), and after the sintering step, the circuit The step of transferring the circuit pattern 13 formed on the alumina substrate 11 to the bonding sheet 15 by matching and compressing the alumina substrate 11 having the pattern 13 with the bonding sheet (S50).
According to the present invention, a low-cost silver paste is printed on an alumina substrate to form a circuit pattern, and a high-temperature sintering forms a circuit pattern having a low electric resistance value, and is then transferred to a bonding sheet to produce a flexible printed circuit board. There is an advantage that can significantly lower the manufacturing cost.

Description

Method for manufacturing flexible printed circuit board, and flexible printed circuit board manufactured by the same {Method for manufacturing flexible printed circuit board, and flexible printed circuit board manufactured by the method}

The present invention relates to a method for manufacturing a flexible printed circuit board and a flexible printed circuit board manufactured by the same, and more particularly, to a method for manufacturing a flexible printed circuit board, which is simple in a manufacturing process and which can reduce manufacturing costs, and a flexible printed circuit board. It relates to a printed circuit board.

Flexible Printed Circuit Boards (FPCBs) are widely used in products such as mobile phone holders, automation devices, camcorders, LCDs, and PDPs that require bending or flexibility when inserting and configuring parts.

A flexible printed circuit board is a circuit board in which a complicated circuit is formed on a flexible insulating film.

Prior art related to this is disclosed in Korean Patent Publication No. 10-2006-0005142 (January 17, 2006) "Flexible printed circuit board and its manufacturing method".

In the flexible printed circuit board, a screen method and an inkjet method of drying a circuit pattern by applying a conductive nano paste to a polyimide film and applying heat are mainly used.

However, since the conductive nano paste and the polyimide film are expensive, the manufacturing cost of the flexible printed circuit board is greatly increased. In addition, since the circuit pattern is made of conductive nano paste, plating of the circuit pattern should be further performed to solve the resistance problem.

Plating has the advantage of low price in the case of electrolytic plating, but the thickness of the plating is difficult to uniform, and electroless plating is more than five times more expensive than electrolytic plating, leading to an increase in manufacturing cost.

In addition, the polyimide film has problems that are discarded during transfer and difficult to handle during transfer.

An object of the present invention is to form a circuit pattern on an inexpensive alumina substrate and high temperature sintering to lower the electrical resistance value, to reduce the manufacturing cost, and to manufacture a flexible printed circuit board having a simple manufacturing process, and the flexible printed fabricated thereby. To provide a circuit board.

According to a feature of the present invention for achieving the above object, the present invention comprises the steps of preparing a ceramic substrate, forming a circuit pattern using a conductive paste on the ceramic substrate, the ceramic with the circuit pattern is formed And sintering the substrate, and after the sintering, matching the ceramic substrate on which the circuit pattern is formed with a bonding sheet and compressing the substrate to transfer the circuit pattern formed on the ceramic substrate to the bonding sheet.

The bonding sheet is a polyimide film having an adhesive layer formed on one surface or both surfaces.

Prior to the transfer of the circuit pattern to the bonding sheet, a step of forming a via hole in the bonding sheet is performed, and the circuit patterns are respectively transferred onto both surfaces of the bonding sheet.

The said electrically conductive paste is silver paste containing silver powder and a binder.

The sintering is carried out at 700 ~ 900 ℃.

In the transferring step, before the ceramic substrate is cooled, the ceramic substrate on which the circuit pattern is formed is matched with a bonding sheet and pressed, so that the adhesive layer melts and adheres to the circuit pattern.

The ceramic substrate is an alumina (Al 2 O 3 ) substrate.

A flexible printed circuit board having circuit patterns formed on one or both surfaces of a polyimide film.

According to the present invention, a low-cost silver paste is printed on an alumina substrate to form a circuit pattern, and a high-temperature sintered circuit pattern is transferred to a bonding sheet to produce a flexible printed circuit board, thereby reducing the manufacturing cost of the flexible printed circuit board. The effect can be greatly lowered.

In addition, the present invention can be used repeatedly because the alumina substrate has the effect of lowering the equipment investment cost.

In addition, the present invention transfers the circuit pattern to the bonding sheet in a state where the heat of the alumina substrate does not cool after high temperature sintering, so that the transfer is easy and takes a short time. Therefore, the productivity of the flexible printed circuit board is improved.

In addition, the present invention significantly lowers the electrical resistance of the high temperature sintering furnace circuit, so it is not necessary to use expensive nano paste or additional plating process, and also prevents the problem of discarding the polyimide film after transfer. The cost savings are great.

1 is a process diagram showing a method of manufacturing a flexible printed circuit board according to the present invention.
2 is a configuration diagram showing a method of manufacturing a flexible printed circuit board having a double-sided structure according to the present invention.
3 is a configuration diagram showing a method for manufacturing a flexible printed circuit board having a cross-sectional structure according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the method of manufacturing a flexible printed circuit board of the present invention, as shown in FIG. 1, a step of preparing a ceramic substrate (S10), a step of forming a circuit pattern using a conductive paste on the ceramic substrate (S20), Sintering the ceramic substrate on which the circuit pattern is formed at a temperature of 700 to 900 ° C. (S30), and after sintering, matching the ceramic substrate on which the circuit pattern is formed to a bonding sheet and compressing the bonded circuit pattern formed on the ceramic substrate. Transferring to the step (S40).

After the transfer, the ceramic substrate is separated from the bonding sheet (S50).

The present invention does not use expensive conductive nano pastes, and uses a ceramic substrate as a base substrate for circuit pattern formation instead of a difficult polyimide film.

The ceramic substrate does not generate dimensional deformation even when sintered at a high temperature.

It is preferable to use an alumina substrate as a ceramic substrate. The alumina substrate exhibits excellent heat resistance characteristics, and does not generate dimensional deformation even when sintered at a high temperature of 700 ° C. or higher, and has excellent adhesion with the conductive paste.

In addition, since the alumina substrate can be used to form a fine pattern and can be repeatedly used, it lowers equipment investment and material cost for manufacturing a flexible printed circuit board.

On the other hand, when the polyimide film is sintered at a high temperature of 300 ° C. or more, shrinkage occurs and defects such as crushing and carbonization occur. Therefore, a circuit pattern is formed by screen printing a conductive paste on an alumina substrate capable of high temperature sintering at 700 ° C or higher.

Screen printing is easy to form a fine pattern, fast curing speed, excellent adhesion and flexibility.

Since the alumina substrate preferably contains a small amount of glass, the purity is preferably 96% or more and less than 99%. The glass component is easily fused with the conductive paste to improve adhesion between the circuit pattern and the alumina substrate.

The conductive paste is a silver paste containing silver powder and a binder.

As the conductive paste containing silver powder increases as the sintering temperature increases, the silver powders stick to each other to increase the density, thereby lowering the electric resistance value. In the flexible printed circuit board, it is important to secure the conductivity and the electrical resistance value must be low to secure the conductivity.

The binder improves the adhesion between the circuit pattern formed after the sintering of the silver paste and the alumina substrate. The binder may be a polyester resin. The silver paste may further include a dispersant for stability in the solvent of the silver powder in addition to the silver powder and the binder.

Sintering at a temperature of 700 ~ 900 ℃ to lower the resistance of the circuit pattern formed on the alumina substrate. Sintering of less than 700 ℃ is ineffective to lower the resistance of the circuit pattern, and the melting point of the silver (Ag) above 900 ℃ is about 962 ℃ may cause a problem that the circuit pattern melts.

The sintering time is preferably about 30 minutes. Since the silver paste decreases in electrical resistance in proportion to the sintering temperature and the sintering time, it is preferable that the sintering temperature and the sintering time of the silver paste be long to lower the electrical resistance of the circuit pattern. However, in this embodiment, since the sintering temperature is high as 700 ~ 900 ℃, the sintering time does not need to be longer than 30 minutes.

In the transfer, the ceramic substrate on which the circuit pattern is formed is matched with the bonding sheet in the state where there is heat before the ceramic substrate is cooled, and pressed, so that the adhesive layer melts and adheres to the circuit pattern.

After sintering, when the temperature of the ceramic substrate is high (in the range of about 200 to 300 ° C), when the bonding sheet is placed on the circuit pattern of the ceramic substrate and pressed, the adhesive layer of the bonding sheet melts due to the heat of the ceramic substrate, thereby adhering the circuit pattern and bonding sheet. It is easy to transfer.

The bonding sheet is for electrically separating and mechanically supporting the circuit pattern. The bonding sheet is a polyimide film having an adhesive layer formed on one or both surfaces. Polyimide film is excellent in heat resistance, thin and flexible, and is suitable for the trend of miniaturized and highly integrated printed circuit boards.

In the case of manufacturing a double-sided flexible printed circuit board, before the step of transferring the circuit pattern to the bonding sheet, a step of forming a via hole in the bonding sheet may be performed, and the circuit patterns may be transferred onto both surfaces of the bonding sheet, respectively.

The flexible printed circuit board of the present invention is a single-sided flexible printed circuit board having a circuit pattern formed on one surface of a bonding sheet or a double-sided flexible printed circuit board having circuit patterns formed on both sides of a bonding sheet, and the circuit patterns of both sides being connected to each other through via holes. .

In the case of the double-sided flexible printed circuit board, since the circuit patterns on both sides may not be connected to each other through the via holes, the circuit pattern of the ceramic substrate may be transferred to the bonding sheet after the conductive paste is filled in the via holes of the bonding sheet.

As the method for filling the conductive paste in the via hole, various methods including screen printing may be adopted.

The bonding sheet is a polyimide film having an adhesive layer formed on one or both surfaces.

In addition to the polyimide film, the bonding sheet may use various kinds of insulating films.

Hereinafter will be described the operation of the preferred embodiment of the present invention.

A method of manufacturing a double-sided flexible printed circuit board by forming a circuit pattern on an alumina substrate and transferring the circuit pattern to a bonding sheet will be described with reference to FIG. 2.

As shown in FIG. 2A, the alumina substrate 11 is prepared, and as shown in FIG. 2B, silver paste is screen-printed on the prepared alumina substrate 11 to form a circuit pattern 13. ). The alumina substrate 11 on which the circuit pattern 13 is printed is sintered through a heating furnace set at 700 to 900 ° C, preferably at 900 ° C.

The bonding sheet 15 is prepared in advance. The bonding sheet 15 is a polyimide film 15b having adhesive layers 15a and 15c formed on both surfaces thereof. The coverlay 19 is further attached to the adhesive layer 15c, and the coverlay 19 is removed and used during transfer.

After sintering, as shown in (d) and (e) of FIG. 2, the alumina substrate 11 having the circuit pattern 13 formed thereon is matched with the bonding sheet 15 in a hot state and pressed, thereby compressing the alumina substrate 11. The circuit pattern 13 formed on the transfer sheet 15 is transferred to the bonding sheet 15.

At this time, the circuit pattern 13 of the alumina substrate 11 and the adhesive layer 15a of the bonding sheet 15 are disposed to face each other, and then matched and pressed. Then, the adhesive layer 15a of the bonding sheet 15 melts to bond the bonding sheet 15 and the circuit pattern 13, and the circuit pattern 13 closes the via hole 17.

After the transfer, as shown in FIG. 2F, the alumina substrate 11 is separated from the bonding sheet 15 and dried. Drying can be carried out at a temperature of 100 ~ 150 ℃.

When the circuit pattern 13 is transferred to one surface of the bonding sheet 15 in the same manner as described above, as shown in FIG. 2G, the bonding sheet 15 is inverted so that the opposite side adhesive layer 15c is on top. After that, the circuit pattern 13a formed on the ceramic substrate 11a is transferred to the adhesive layer 15c in the same manner as described above with heat.

Then, as illustrated in FIG. 2H, the circuit patterns 13 and 13a of the alumina substrate 11 are transferred to the adhesive layers 15a and 15c on both sides of the bonding sheet 15, and the circuits on both sides are transferred. The patterns 13 and 13a are electrically connected to each other by filling the via holes 17.

Meanwhile, the cross-sectional flexible printed circuit board prepares an alumina substrate 11, as shown in FIG. 3 (a), and silver paste on the prepared alumina substrate 11, as shown in FIG. 3 (b). Screen printing to form a circuit pattern (13). The alumina substrate 11 on which the circuit pattern 13 is printed is sintered through a heating furnace set at 700 to 900 ° C, preferably at 900 ° C.

After sintering, as shown in (d) and (e) of FIG. 3, the alumina substrate 11 having the circuit pattern 13 formed thereon is matched with the bonding sheet 15 in a hot state and pressed, thereby compressing the alumina substrate 11. The circuit pattern 13 is transferred to the bonding sheet 15. After the transfer, the ceramic substrate is separated from the bonding sheet. This results in a cross-section flexible printed circuit board, as shown in FIG.

This invention is within the scope of the basic technical idea that many modifications are possible to those of ordinary skill in the art, as well as the scope of the invention should be interpreted based on the appended claims. .

11: Alumina substrate 13: Circuit pattern
15: bonding sheet 15a, 15c: adhesive layer
15b: polyimide film 17: via hole
19: Coverlay

Claims (8)

Preparing a ceramic substrate;
Forming a circuit pattern on the ceramic substrate using a conductive paste;
Sintering the ceramic substrate having the circuit pattern formed thereon;
And after the sintering, transferring the circuit pattern formed on the ceramic substrate to the bonding sheet by compressing and matching the ceramic substrate on which the circuit pattern is formed with the bonding sheet.
In the transferring step, before the ceramic substrate is cooled, the flexible printed circuit, wherein the ceramic substrate on which the circuit pattern is formed is matched with a bonding sheet and pressed, so that the adhesive layer of the bonding sheet melts and adheres to the circuit pattern. Method of manufacturing a substrate. The method according to claim 1,
The bonding sheet is a manufacturing method of a flexible printed circuit board, characterized in that the polyimide film with an adhesive layer formed on one side or both sides. The method according to claim 1,
Before the circuit pattern is transferred to the bonding sheet, forming a via hole in the bonding sheet,
The method of manufacturing a flexible printed circuit board, characterized in that for transferring the circuit pattern on each side of the bonding sheet. The method according to claim 1,
The conductive paste is a silver paste containing a silver powder and a binder, the method of manufacturing a flexible printed circuit board. The method according to claim 1,
The sintering method of manufacturing a flexible printed circuit board, characterized in that carried out at 700 ~ 900 ℃. delete The method according to claim 1,
The ceramic substrate is a method for manufacturing a flexible printed circuit board, characterized in that the alumina (Al 2 O 3 ) substrate. A flexible printed circuit board manufactured by the method of any one of claims 1 to 5 and 7, wherein a circuit pattern is formed on one or both surfaces of the insulating film.
KR1020130011947A 2013-02-01 2013-02-01 Method for manufacturing flexible printed circuit board, and flexible printed circuit board manufactured by the method KR102044497B1 (en)

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KR102044497B1 true KR102044497B1 (en) 2019-11-14

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20220062891A (en) 2020-11-09 2022-05-17 현대자동차주식회사 Printed circuit and manufacturing method thereof
KR20230089742A (en) 2021-12-14 2023-06-21 경희대학교 산학협력단 Method for manufacturing flexible circuit board, and flexible circuit board manufactured by the method

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05327185A (en) * 1992-05-22 1993-12-10 Tanaka Kikinzoku Kogyo Kk Manufacture of flexible circuit board
KR20120130639A (en) * 2011-05-23 2012-12-03 주식회사 아모그린텍 Double layer fpcb and manufacting method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20220062891A (en) 2020-11-09 2022-05-17 현대자동차주식회사 Printed circuit and manufacturing method thereof
KR20230089742A (en) 2021-12-14 2023-06-21 경희대학교 산학협력단 Method for manufacturing flexible circuit board, and flexible circuit board manufactured by the method

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