KR101063034B1 - Surface treatment method of keypad - Google Patents

Abstract

The present invention provides a circuit pattern including a key switch part formed in a plurality of rows and columns on a circuit board, a dome switch part formed around the key switch part, a circuit pattern part formed on the circuit board, and a general pad. Processing PSR (Photo Solder Resist) on the unit; Printing a conductive material on the dome switch unit or the key switch unit or surfaces of the dome switch unit and the key switch unit; And After printing the conductive material provides a surface treatment method of the keypad comprising the step of processing the organic solderability preservative (OSP) on the general pad.

Therefore, by simplifying the process by reducing the number of surface treatment process of the keypad, it is possible to reduce the surface treatment cost, improve the workability to improve the work rate.

Description

Surface treatment method of keypad {Method for Surface Treatment of Key Pad}

The present invention relates to a surface treatment method of the keypad, and more particularly, to a surface treatment method of the keypad that can reduce the cost for the surface treatment process.

In general, a keypad is provided as a means for transmitting an input signal such as an electronic product or a portable wireless terminal. The keypad includes a key switch unit and a dome switch unit formed in a dome shape to have a feeling of operation on a printed circuit board. When the dome switch unit is pressed, the structure is capable of generating a signal by touching a contact point of the key switch unit of the printed circuit board.

Looking at the surface treatment method of the keypad, conventionally, the keypad surface treatment method, PSR (Photo Solder Resist) processing step to prevent the short circuit of the circuit by preventing exposure of the copper foil of the printed circuit board, and masking on the general pad portion (Masking), the electroless plating step, the peeling step to remove the masking and the organic solderability preservative (OSP) process.

However, the surface treatment method of the conventional keypad has a large number of processing steps such as the PSR treatment step, the masking step, the electroless plating step, the peeling step, and the OSP treatment step, and thus the processing cost is high. In the case of a keypad having a row dome switch unit and a key switch unit, the dome switch unit and the key switch unit need to be individually masked and electroless plated and masking removal work is difficult and cumbersome.

In addition, the conventional surface treatment method of the keypad has a galvanic phenomenon in the OSP treatment step, resulting in a non-uniform OSP coating, thereby resulting in non-uniform soldering property, and also due to galvanic corrosion occurring in the OSP treatment step. There is a problem that Cu erosion occurs, and furthermore, even if the potential is controlled by an active ingredient (surface potential modifier) as a method for preventing the galvanic phenomenon, it must be treated as a separate process before the OSP treatment step. The process was complicated and tricky.

The present invention, by reducing the number of surface treatment process of the keypad to simplify the process can reduce the surface treatment cost, improve the workability to improve the work rate, prevent the galvanic phenomenon in the OSP treatment step without a separate process keypad It is an object of the present invention to provide a surface treatment method of the keypad to improve the quality of the.

The present invention provides a circuit pattern including a key switch part formed in a plurality of rows and columns on a circuit board, a dome switch part formed around the key switch part, a circuit pattern part formed on the circuit board, and a general pad. Processing PSR (Photo Solder Resist) on the unit; Printing a conductive material on the dome switch unit or the key switch unit or surfaces of the dome switch unit and the key switch unit; And After printing the conductive material provides a surface treatment method of the keypad comprising the step of processing the organic solderability preservative (OSP) on the general pad.

At this time, after printing the conductive material may further include a step of drying, and the present invention preferably the conductive material is a carbon paste, the printing of the conductive material is the conductive material in the dome switch unit It is good to screen print.

The surface treatment method of the keypad according to the present invention can reduce the surface treatment cost because the surface treatment using a cheap carbon paste, rather than the conventional plating treatment using expensive gold, can reduce the number of surface treatment process of the keypad It is possible to improve the work rate by improving the performance, and to improve the quality of the keypad by preventing the galvanic phenomenon in the OSP processing step without a process to prevent galvanic corrosion.

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

1 is a flowchart illustrating a keypad surface treatment method according to an embodiment of the present invention.

2 is a perspective view schematically showing a keypad according to an embodiment of the present invention, Figures 3 and 4 are a cross-sectional view showing a layer structure of the keypad along the line I-I of Figure 2 and a plan view along the line II-II.

First, the surface treatment method of the keypad according to an embodiment of the present invention, as shown in Figure 1, the step of processing the PSR (Photo Solder Resist) on the keypad (S10), and the step of printing a conductive material after the PSR (S20) And, after printing the conductive material, an organic solderability preservative (OSP) process (S40). Here, the keypad applied to the embodiment of the present invention, as shown in Figure 2, the circuit board 10, the key switch unit 20 formed in a plurality of rows and columns on the circuit board 10, the key switch A dome switch part 30 formed around the part 20, a general pad 50 formed on the circuit board 10, on which components are mounted, and a circuit pattern part 60 part are formed.

The step (S10) of processing PSR (Photo Solder Resist) on the keypad serves to prevent oxidation as a pretreatment step performed before the subsequent process, and includes the key switch unit 20, the dome switch unit 30, and the like. The circuit pattern portion 60 except for the general pad 50 is subjected to surface treatment with a PSR ink.

After the PSR treatment, a step of printing with a conductive material is performed (S20), and the printing of the conductive material is performed by the dome switch unit 30, the key switch unit 20, or the dome switch unit 30. And it is made by printing a conductive material on the surface of the key switch unit 20. In this case, the conductive material may be a carbon paste having excellent oxidation characteristics, and the printing method using the conductive material may be performed by screen printing. However, in one embodiment, the printing method for printing the conductive material and the conductive material may be any conductive material and printing method that can achieve the object of the present invention.

On the other hand, the carbon paste is printed on the dome switch unit 30 and the key switch unit 20, respectively, so that the key switch unit 20 and the dome switch unit 30 does not short each other (shot) occurs. It is preferable to print with a predetermined printing area and a gap between the key switch unit 20 and the dome switch unit 30, and to print at a predetermined thickness in consideration of a desired conductivity or the like. Here, the thickness of the key switch unit 20 and the dome switch unit 30 may be printed in the range of 10 μm to 30 μm in consideration of reliability and performance of quality.

In addition, the carbon paste may be formed by mixing a resin or the like in the carbon powder. However, the mixing composition of the carbon paste may be used by mixing a variety of auxiliary components with the carbon powder as a main component if only the purpose of achieving conductivity and printing to a predetermined thickness.

As described above, in the embodiment of the present invention, since the printing method using a conductive material rather than the conventional electroless plating method is applied to the dome switch unit 30 and the key switch unit 20, OSP processing to be performed later. It can prevent galvanic corrosion which may occur at the stage. Here, the galvanic corrosion is a phenomenon in which corrosion is promoted on the surface by a potential difference when dissimilar metals having different electric potentials are deposited in a solution in an electrically connected state. This results in the formation of a eroded local Cu surface.

On the other hand, the embodiment of the present invention may further include a step (S30) after printing the conductive material. Here, the drying conditions in the drying step may be any condition that facilitates the OSP treatment to be carried out later, or the PSR ink and the conditions for drying the printed conductive material.

The OSP treatment is performed by OSP (Organic Solderability Preservative) treatment on the general pad 50, and the keypad including the general pad 50 reacts with oxidation or moisture in the air generated by direct contact with air. It absorbs hydrogen and prevents it from contacting the atmosphere. Here, the detailed description of the OSP process will be omitted since it is substantially the same as the technical content of the general OSP process to those skilled in the art.

Looking at the layer structure of the keypad formed through the surface treatment method of the keypad according to the embodiment of the present invention as follows. 3 and 4 are side cross-sectional views showing the layer structure of the keypad after the keypad surface treatment method according to the embodiment of the present invention described above. As a plan view, referring to FIG. 3, the upper portion of the circuit board 10 is shown. The key switch unit 20, the dome switch unit 30 formed around the key switch unit 20, the general pad 50, and the circuit pattern unit 60 are formed. Here, the PSR layer 62 is formed on the upper surface of the circuit pattern part 60 through the PSR process, and the OSP layer 52 is formed on the general pad 50 through the OSP process. In addition, conductive materials layers 22 and 32 formed by printing conductive materials are formed on upper surfaces of the dome switch unit 30 and the key switch unit 20, and the conductive material layers 22 and 32 are formed on the upper surfaces of the dome switch unit 30 and the key switch unit 20. A dome portion (not shown) is formed in a dome shape on the key switch portion 20. At this time, the dome portion is made of a conductive material of a material having elasticity that can restore its shape, and is pressed when the operator presses so that the bottom surface contacts the conductive material layer 32 and the key switch unit 20 and the dome When the switch unit 30 is turned on, while the operator does not pressurize, the switch unit 30 is restored to its original state through a restoring force so that the key switch unit 20 and the dome switch unit 30 are not connected.

Here, the conductive material layers 22 and 32 are preferably printed with carbon paste, and the dome portion is also preferably printed with carbon paste, but has a function and purpose of having elasticity and elasticity to achieve the purpose of the dome portion. Anything that can be achieved is possible.

As described above, the surface treatment method of the keypad according to a preferred embodiment of the present invention, in the surface treatment of the conventional dome switch unit 30 and the key switch unit 20, the masking step, electroless plating treatment, masking Since it does not go through a peeling step, the process is simple, thereby reducing costs and improving workability. In addition, in the embodiment of the present invention, since the dome switch unit 30 and the key switch unit 20 are printed using carbon paste, galvanic corrosion can be prevented, thereby improving product quality and reliability.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a flowchart illustrating a keypad surface treatment method according to an embodiment of the present invention.

2 is a perspective view schematically showing a keypad according to an embodiment of the present invention.

3 and 4 are cross-sectional views showing the layer structure of the keypad along the line I-I of FIG. 2 and a plan view along the line II-II.

<Brief description of symbols for the main parts of the drawings>

10 ... Circuit board 20 ... Key switch part

22,33 ... conductive material layer 30 ... dome switch

50 ... Normal pad 60 ... Circuit pattern part

Claims (5)

In the surface treatment method of a keypad comprising a key switch portion formed in a plurality of rows and columns on a circuit board, a dome switch portion formed around the key switch portion, a circuit pattern portion formed on the circuit board and a general pad, PSR (Photo Solder Resist) processing on the circuit pattern portion; Printing carbon paste on a surface of the dome switch unit or the key switch unit or the dome switch unit and the key switch unit; And After printing the carbon paste, the surface treatment method of the keypad comprising the step of (Organic Solderability Preservative) processing on the general pad. delete The method according to claim 1, And after the carbon paste is printed, drying the surface. The method according to claim 1, The printing of the carbon paste may include: A surface treatment method of a keypad for printing the carbon paste on the dome switch unit. The method according to claim 1, The printing of the carbon paste may include: The surface treatment method of the keypad which screen-prints the said carbon paste on the surface of the said dome switch part.

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