KR100947921B1 - High ductility Au surface treatment plating method of flexible printed circuit board - Google Patents

Abstract

The present invention relates to a method for plating a highly flexible Au surface treatment of a flexible printed circuit board, and more specifically, to a surface treatment portion including a wire bonding portion for semiconductor mounting and a soldering portion directly bonded to an external component or mounted thereon. A method for plating a flexible printed circuit board having a predetermined circuit pattern, the method comprising: a) degreasing, pickling, and polishing a flexible printed circuit board; b) forming an electroless nickel plating layer using an electroless nickel plating solution in the wire bonding portion and the soldering portion; c) forming a gold plating layer on the electroless nickel plating layer; And d) adsorbing or coating a sealing treatment agent containing a phosphate surfactant, a polyamine-based ring compound, and water on the gold plated layer.

According to the present invention, corrosion resistance can be improved by sealing a pinhole formed in a thin gold plated layer during electroless gold plating.

Flexible, Au, Sealed, Flexible Printed Circuit Board, Pickling, Abrasive

Description

High ductility Au surface treatment plating method of flexible printed circuit board

The present invention relates to a surface treatment plating method of a flexible printed circuit board, and more particularly to a surface treatment plating method of forming a plating layer on the surface in order to protect the copper layer of the flexible printed circuit board.

In general, a rigid, flexible, or rigid printed circuit board has a surface treatment part including a wire bonding part for mounting a semiconductor and a soldering part for mounting a printed circuit board with components such as an IC chip and a RAM.

The surface treatment part is usually made of a copper material, and the copper exposed to the outside may be oxidized and corroded over time, so that conventional soldering and wirebonding characteristics may not be damaged by corrosion. After plating or electroless nickel plating, the electrolytic gold plating or the electroless gold plating was about 0.5 μm, thereby forming a surface treatment portion in which external components were directly bonded or mounted.

Here, the electro-nickel plating or electroless nickel plating not only protects copper even under corrosion or long-term storage conditions, but also serves to prevent interdiffusion by interfacial plating between the copper layer and gold plating.

However, when the flexible printed circuit board is surface-treated by the electroless gold plating method of electroless gold plating after the conventional electroless nickel plating, there is a problem that cracks occur during bending.

In order to improve the problems of the conventional electroless nickel plating and the electroless gold plating method, when the electrolytic direct gold plating method of directly electroplating gold without electroless nickel plating is performed, the ductility is excellent, but the use of a large amount of expensive gold There was a problem that the manufacturing cost is high, and in the electrolytic direct gold plating method, since a plating line is required, wrinkles, foreign matters, imprints, and unplating defects due to the plating line may be increased.

In addition, in the electroless gold plating method, since the gold plating layer is thinly formed, a pinhole having a predetermined size is formed, and corrosive substances such as moisture, chloride, emulsion, salt, and the like penetrate the pinhole to corrode the base material. Reactants generated by corrosion precipitated on the surface, causing problems such as an increase in contact resistance.

The present invention has been made to solve the above problems, and an object thereof is to provide a high-ductility Au surface treatment method of a flexible printed circuit board capable of maintaining high ductility without using a lot of expensive gold.

In order to achieve the above object, a high-ductility Au surface treatment plating method of a flexible printed circuit board of the present invention includes a surface treatment part including a wire bonding part for semiconductor mounting and a soldering part directly bonded to an external component or mounted thereon. A plating method of a flexible printed circuit board having a predetermined circuit pattern, the method comprising: a) degreasing, pickling, and polishing the flexible printed circuit board; b) forming an electroless nickel plating layer by using an electroless nickel plating solution on the wire bonding part and the soldering part; c) forming a gold plated layer on the electroless nickel plated layer; And d) adsorbing or coating a sealing treatment agent containing a phosphate surfactant, a polyamine-based ring compound, and water on the gold plated layer.

Here, the step c) is preferably deposited for 10-100 seconds the sealing agent at 40 ~ 80 ℃.

When the sealing treatment agent is deposited at a temperature of less than 40 ℃ there is a problem that it is not economical because the deposition time is long, there is a problem that the life of the solution is shortened when deposited at a temperature exceeding 80 ℃. In addition, when the deposition time is less than 10 seconds, there is a problem that the sealing process may not be made completely, if there is more than 100 seconds there is no difference in the sealing effect so there is a problem that it is uneconomical to increase the production time.

In addition, the sealing agent is preferably containing 1 to 3% by weight of phosphate surfactant (Phosphate surfactant), 1 to 4% by weight of the polyamine-based ring compound and 93 to 98% by weight of water.

In addition, the thickness of the electroless nickel plating layer is 1 ~ 8㎛, it is preferable that the thickness of the gold plating layer is 0.01 ~ 0.1㎛.

In addition, the electroless nickel plating solution is 30 to 40% by weight of nickel sulfate, 60 to 70% by weight of ion-exchanged water, 35 to 45% by weight of sodium dental phosphate, and 5 to 15% by weight of ammonium maleate It is preferable to contain the 2nd solution which mixed% and 45-55 weight% of ion-exchange water.

In addition, the electroless nickel plating solution is 10 to 20% by weight of sodium hydroxide, 1 to 10% by weight of disodium succinate, and 75 to 90% by weight of ion-exchanged water or 25 to 35% by weight of sodium dental phosphate It is preferable that one or more solutions of the fourth solution in which%, 10 to 25% by weight of ammonium lactate, and 45 to 55% by weight of ion-exchanged water are further added.

Further, the electroless nickel plating solution may be a mixture of the first solution, the second solution, the third solution and the fourth solution in various mixing ratios according to other conditions such as layer thickness, but is preferably 4: 1. A mixture of 1: 1: 0.9 is used.

As described above, the highly flexible Au surface treatment plating method of the flexible printed circuit board of the present invention,

First, since the amount of gold can be significantly reduced compared to the electrolytic direct gold plating method, there is an advantage that the production cost can be reduced and the productivity increase accordingly.

Second, there is an advantage that the thin gold plating alone is excellent in ductility to prevent the bending crack of the flexible printed circuit board.

Third, by sealing the pinhole that may be involved in the thin gold plating it is possible to prevent the corrosion of the product, thereby improving the product reliability.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, various equivalents that may be substituted for them at the time of the present application It should be understood that there may be water and variations.

Hereinafter, referring to FIGS. 1 and 2, a method for plating a highly flexible Au surface treatment of a flexible printed circuit board according to an exemplary embodiment of the present invention will be described. 1 is a block flow diagram illustrating a method for plating a highly flexible Au surface treatment of a flexible printed circuit board according to an exemplary embodiment of the present invention, and FIG. 2 is a method for plating the high flexible Au surface treatment of a flexible printed circuit board of FIG. Schematic diagram showing the process flow.

Referring to Figure 1, a method for plating a high-ductility Au surface treatment of a flexible printed circuit board according to an embodiment of the present invention is a) degreasing, pickling and polishing step (S110), b) nickel plating step (S120), c ) Gold plating step (S130) and d) sealing processing step (S140).

Referring to FIG. 2, the flexible printed circuit board 100 having a predetermined circuit pattern (not shown) includes a surface treatment part 110 including a wire bonding part for semiconductor mounting and a soldering part for coupling with external components. Since this process is due to the manufacturing method of the flexible printed circuit board 100 well known in the art, a detailed description thereof will be omitted.

The surface treatment unit 110 is generally made of a copper material to perform a surface treatment plating method to protect such a copper layer.

First, prior to performing a surface treatment for protecting a copper layer exposed on the surface of the flexible printed circuit board 100, photosolder resist (PSR) is generally applied to the surface treatment unit 110 of the flexible printed circuit board 100. The photo solder resist layer 130 is formed by applying to portions except for) to serve as a resist for plating to be described later.

That is, a dry film is applied to the photosolder resist layer 130, and selectively exposed only a portion of the photosolder resist layer 130 on the surface treatment unit 110 through exposure and development.

As such, when the surface treatment unit 110 is exposed to the outside in the flexible printed circuit board, contaminants of oils and fats adhered to the material surface are removed by degreasing.

The degreasing method may include various methods such as emulsion degreasing, alkali degreasing, electrolytic degreasing, ultrasonic degreasing, but preferably electrolytic degreasing.

After removing contaminants on the surface by the degreasing process, pickling and polishing are performed using an abrasive containing fluorine ions to remove tin oxide, phosphorus component, and beryllium copper oxide film of phosphor bronze (S110).

Unlike the sodium peroxide-based abrasive, the fluorine-containing abrasive has a role of preventing the substrate from discoloring during polishing, and has an advantage of preventing corrosion.

Next, the electroless nickel plating solution is contacted to form an electroless nickel plating layer 150 (S120).

Here, the thickness of the electroless nickel plating layer 150 is preferably 1 ~ 8㎛.

Since the thickness of the electroless nickel plating layer 150 is formed as described above, there is an advantage that the amount of gold plated can be significantly reduced as compared with the conventional electrolytic direct gold plating method.

In addition, the electroless nickel plating solution is 30 to 40% by weight of nickel sulfate, 60 to 70% by weight of ion-exchanged water, 35 to 45% by weight of sodium dental phosphate, and 5 to 15 in ammonium maleate It is preferable to contain the 2nd solution which mixed amount% and 45-55 weight% of ion-exchange water.

In addition, the electroless nickel plating solution is 10 to 20% by weight of sodium hydroxide, 1 to 10% by weight of disodium succinate, and 75 to 90% by weight of ion-exchanged water or 25 to 35% by weight of sodium dental phosphate More preferably, at least one solution of the fourth solution in which%, 10 to 25% by weight of ammonium lactate, and 45 to 55% by weight of ion-exchanged water is added is added.

The electroless nickel plated layer 150 plated by the electroless nickel plating solution has an advantage in that the crystal structure is formed in the longitudinal direction, and the adhesion of the plating is strong and high ductility is exhibited.

Subsequently, by forming the gold plating layer 170 on the electroless nickel plating layer 150, the flexible printed circuit board 100 is subjected to high ductility Au surface treatment (S130).

Thus, the flexible printed circuit board 100 having the high ductility Au surface treatment exhibits excellent ductility even when a large amount of expensive gold is not included, and also shows excellent characteristics in soldering properties.

However, since the gold plating layer 170 is formed as a thin layer, c) the pinhole 171 may be formed after the gold plating step S130, and as described above, corrosion may occur due to the pinhole 171. have.

Accordingly, by sealing the pin pole 171 using a sealing agent, it is possible to prevent corrosion by the pinhole 171 and to improve corrosion resistance (S140).

The sealing treatment agent forms the sealing treatment layer 190 by an adsorption or coating method. In addition, during the sealing process, it is preferable to deposit the sealing agent for 10 to 100 seconds at 40 ~ 80 ℃.

In addition, the sealing agent is preferably containing 1 to 3% by weight of a phosphate surfactant (Phosphate surfactant), 1 to 4% by weight of the polyamine-based ring compound and 93 to 98% by weight of water.

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this, The person of ordinary skill in the art to which this invention belongs, Of course, various modifications and variations are possible within the scope of equivalent claims.

1 is a block flow diagram illustrating a method for plating a highly flexible Au surface treatment of a flexible printed circuit board according to an exemplary embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a process flow according to the high ductility Au surface treatment plating method of the flexible printed circuit board of FIG. 1.

<Description of the symbols for the main parts of the drawings>

100: flexible printed circuit board 110: surface treatment

130 photosolder resist layer 150 electroless nickel plated layer

170: gold plated layer 171: pinhole

190: sealing layer

Claims (5)

In the plating method of a flexible printed circuit board having a predetermined circuit pattern, the surface bonding portion comprising a wire bonding portion and a flexible printed circuit board for semiconductor mounting is directly bonded to an external component or a soldering portion to which the component is mounted, a) degreasing, pickling and polishing the flexible printed circuit board; b) forming an electroless nickel plating layer by using an electroless nickel plating solution on the wire bonding part and the soldering part; c) forming a gold plated layer on the electroless nickel plated layer; And d) adsorbing or coating a sealing agent containing a phosphate surfactant, a polyamine-based ring compound, and water on a gold plated layer, The plating method of the high-ductility Au surface treatment of a flexible printed circuit board, characterized in that the sealing treatment agent is deposited for 10 to 100 seconds at 40 ~ 80 ℃. delete The method of claim 1, The sealing agent is a high ductility Au of a flexible adult circuit board, characterized in that it contains 1 to 3% by weight of a phosphate surfactant, 1 to 4% by weight of a polyamine ring compound, and 93 to 98% by weight of water. Surface treatment plating method. The method of claim 1, The electroless nickel plating solution is 30 to 40% by weight of nickel sulfate, 35 to 45% by weight of sodium phosphate, and 1 to 5% by weight of ammonium maleate And a second solution containing 45 to 55% by weight of ion-exchanged water, wherein the flexible Au surface treatment plating method of the flexible printed circuit board is performed. The method of claim 4, wherein The electroless nickel plating solution comprises 10 to 20% by weight of sodium hydroxide, 1 to 10% by weight of disodium succinate, and 75 to 90% by weight of ion-exchanged water, or 25 to 35% by weight of sodium dental phosphate, And 10-25 wt% of ammonium lactate and 45-55 wt% of ion-exchanged water are further added with one or more solutions of the fourth flexible Au surface treatment plating method of a flexible printed circuit board.

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