WO2005125158A1

WO2005125158A1 - Metal keypad for portable telephone and manufacturing method of the same

Info

Publication number: WO2005125158A1
Application number: PCT/KR2004/001807
Authority: WO
Inventors: Tae-Sik Seo
Original assignee: Motorola, Inc.
Priority date: 2004-06-22
Filing date: 2004-07-21
Publication date: 2005-12-29
Also published as: KR100525320B1; KR20050018743A

Abstract

The present invention relates to a metal keypad for portable telephone and manufacturing method of the same, and in detail, to metal keypad for portable telephone including thin metal touch pad united base and key top and its manufacturing method. The metal keypad for a portable telephone according to the present invention is approx.0.8mm thick by unifying the key top, the base, and the front housing using a very tiny metal slice, and it is very convenient to use since the button size can be enlarged by dividing the button part on which letters or figures are printed with a thin perforating line, it has excellent durability as it is manufactured with metal, and a touch sense has improved due to inherent elasticity of metal. Furthermore, the metal keypad for a portable telephone according to the present invention has an excellent visual effect due to inherent gloss of metal, and it makes itself look like a quality one by enabling the light from a source of light on the bottom of the metal touch pad to pass by forming a translucent film on the printed letters or figures on the metal touch pad.

Description

METAL KEYPAD FOR PORTABLE TELEPHONE AND

MANUFACTURING METHOD OF THE SAME

Technical Field

The present invention relates to a metal keypad for portable telephone and

manufacturing method of the same, and in detail, to a metal keypad for a portable

telephone and its manufacturing method that is able to make the thickness of a

mobile phone thin by unifying a base, a key top, and a front housing through a

very thin metal touch pad.

Background Art

Generally, keypads are mounted on mobile phones, remote control devices

and PDAs, and are used as an input means for transmitting the user's input signal

to a printed circuit board.

For conventional keypads, a key top(lθ) and a base(20) arranged on the

lower side of a front housing are connected through a connection section(30),

like a keypad for a portable telephone, the cross section of which is shown in FIG.

6. The said key top(lθ) and a base(20) are connected to a front housing(40) to

form the exterior appearance of a mobile phone. The said key top(lθ) has a structure that protrudes toward the outside of a hole formed on the front

housing(40). The said key top(lθ) and a printed circuit board(PCB)(60) in which

a dome switch(50) is mounted on the lower side of a base(20) are designed to be

connected to a key top(lθ) with a predetermined space. On the lower side of the

key top is formed a projection(l 1) to press the dome switch. A light source(70)

is arranged in the backside of the key top in order to distinguish the characters or

the diagrams printed outside of the said key top(lθ) in darkened conditions. An

LED(light emitting diode) was used as a light source in the past, but recently, the

use of thin- film EL(electro luminescence) lamp sheets has increased remarkably

and these are characterized by the excellent uniformity of light. Power

consumption is also minimal, and they are very advantageous for use in slim and

lightweight products.

Disclosure of Invention Tehnical Problem

The conventional keypad has a structure that a dome switch and a source

of light are set up in PCB, and a key top, a base and a front housing are combined

on it, and there is certain space between PCB and the projecting part of the

bottom of the key top. Therefore, the thickness of the total keypad is approx 2mm

to approx. 5mm, and it has the limit to making the keypad thin and light. In

addition, conventional keypad has the fundamental limit to making the button size large since the button section of the key top must be exposed to the hole of

the front housing.

In addition, the key top and the front housing that are disclosed to the

exterior get easily scratched and dirty as they are formed of plastics or synthetic

resin or silicon rubber, and they have the limit even to making products look

quality ones due to inherent color of the above texture and light absorption of the

surface.

Technical Solution In order to solve the aforementioned technical problems, a metal keypad

according to the present invention is comprised of a metal touch pad that is

formed of thin metal strip on which letters and figures are etched on the top and

resin pad which is combined to the back of metal strip so that it makes buffing

when touching dome switch, a printed circuit board (PCB) which is located on

the bottom of the metal touch pad and has the fixed contact point in the

designated position, a dome switch which is located on the upper side of the

printed circuit board and is contacted to the fixed contact point on the printed

circuit board due to the pressure of the touch pad, and a light source which is set

up among the metal touch pad and PCB. Then, the thickness of the said thin metal strip is formed between

0.1mm~0.5mm, but that of 0.2mm is desirably favorable, and the said metal touch pad has a characteristic of setting up for perforating line which is vertically

penetrated in the fixed line on the top according to the position and the

appearance of the said letters or figures so that the dome switch on PCB can be

easily pushed by pressure to be added from the user. Also, it is desirable to make the said metal touch pad plated and coated

with metal to prevent abrasion, not make fingerprints left, and prevent any scar

from occurring, and it is also desirable to cover the said perforating line formed

in the metal touch pad with translucent thin film such as epoxy or ultraviolet

setting resin to prevent penetration by alien matters and let the light from the

light source in the interior of the key pad released outward.

The resin film is combined on the top and the bottom of the resin pad of

the said metal touch pad, and it is desirable for the resin film on the bottom to

have the very tiny projecting part to contact the dome switch.

In others, the above PCB, dome switch, and a light source are composed

of the public notice technology.

The manufacturing method of the metal touch pad for the portable

telephone according to the present invention, is composed of the thin metal strip

processing step, the resin pad manufacturing step, and the step for combining

these. First, a thin metal strip processing step is composed of etching process to

etch the perforating line, letters, and figures in a non-processed metal slice with

the metal etching technique; primary plating process to execute metal plating in

the said metal slice to prevent abrasion on the surface; translucent formation

process to form a translucent film on the etched letters and figures by etching

process; spin process to etch and print spin patterns having the fixed slop on the

said metal slice for looking good; press process to make the thin metal strip

curved by spin process even; secondary plating process to coat the plating film

on the top eliminated by the spin process; surface coating process to paint the

surface of the metal slice to enhance durability of the keypad and prevent

fingerprints from occurring; inspection process to inspect perfection of the metal

keypad which is made through the said processes.

All the techniques used in metal etching at present including wet

chemical etching technique or dry plasma etching technique are applicable to the

said etching process, and it is desirable to use brass slice or stainless steel slice

for the said etching process, and other metal slice could be used.

On the said primary plating process, it is desirable to use nickel as plating

material, and plating is made by electric plating or chemical plating from public

notice technology. At this time, in the case of using corrosion-proof metal

material such as stainless steel, the primary plating process to prevent abrasion is

possible to omit. On the said translucent film formation process, it is desirable to use epoxy

resin or ultraviolet setting resin for the material of translucent film, and

translucent film is formed by injecting epoxy resin or ultraviolet setting resin in

etched letters or figures by dry process. On the above spin process, spin pattern with equal slop is etched on the

top surface of the thin metal strip using a spin cutting machine. The spin process

is not an essential process for the metal touch pad.

On the said secondary plating process, it is possible to plate with colored

metal such as cobalt to get wanted color, which plays a role to prevent abrasion

by coating plating film again on the top eliminated by spin process. The

secondary process can be omitted in case of using corrosion-proof metal material

as mentioned in the primary plating process.

On the said surface coating process, hard coating on the surface of the thin

metal strip is executed using spray, and on the said inspection process imprinting,

transformation, size, and surface status of the completed metal film are finally

inspected.

Meanwhile, all the public notice technology for appearance processing can

be applicable to the above thin metal strip processing step to add the fixed pattern

and the specific color to metal slice. For example, a specific metal can be added

by electrotyping plating for adding the fixed pattern and color to the thin metal

strip, forming the fixed pattern on the thin metal strip by etching, and putting the fixed pattern on the thin metal strip by press molding, etc. It is desirable to add

these processes after the etching process or before the surface coating process.

Next, the resin pad manufacturing step is composed of film printing

process to print various colors on the plastic film to be set in the middle of the

resin pad; film cutting and punching process to cut and punch the color-printed

film for meeting mold; back structure primary molding process to settle and mold

the resin film on the back of the film with heat pressing; frontal structure

secondary molding process to coat the resin film on the front of primarily molded

product; forging process to forge the exterior of the resin pad which was molded

on the front and the back; inspection process to inspect the related specifications.

It is desirable to use silicon resin for the said resin, and it is desirable to use

polycarbonate film for the said plastic film.

Finally, the metal touch pad is completed by compression joint process of

compressing the thin metal strip completed by the said thin metal strip processing

step and the resin pad completed by the said resin pad manufacturing step using

adhesive.

Advantageous Effects

The metal key pad for a portable telephone according to the present

invention described on the above has a very favorable effect for thinness of a mobile phone by reducing the thickness of the key pad by approx.0.8mm by

unifying a key top, a base, and a front housing, using a very thin metal touch pad

in a different way from the conventional keypad for a portable telephone, and it

has an effect to improve convenience by enlarging the button size through

clearing the division between key top and front housing, and dividing the button

part with letters of figure printed with thin perforating line.

In addition, the metal keypad for a portable telephone according to the

present invention has such an excellent durability that scars do not easily occur,

and it does not easily become dirty despite using a long time due to consisting of

metal in a way different from the conventional keypad using plastic or synthetic

resin or silicon rubber, and has an improved touch sense of the key due to

inherent elasticity of metal.

Furthermore, the metal keypad for a portable telephone according to the

present invention has an excellent visual effect due to inherent gloss of metal,

and it makes itself look like a quality one by enabling the light from a light

source on the bottom of the metal touch pad to pass by forming a translucent film

on the printed letters or figures on the metal touch pad.

Brief Description of Drawings Fig. 1 is a cross sectional view showing the cross of the metal keypad for a

portable telephone according to the present invention.

Fig. 2 is a cross sectional detail view enlarging the cross of the metal

touch pad of the metal keypad for a portable telephone according to the present

invention.

Fig. 3 is a plane view of the metal touch pad produced according to an

embodiment of the present invention.

Fig. 4 is a rear side view of the metal touch pad produced according to an

embodiment of the present invention. Fig. 5 is a procedure showing an embodiment of the manufacturing

method of the metal touch pad for a portable telephone according to the present

invention.

Fig. 6 is a cross sectional view showing a conventional keypad for a

portable telephone.

Best Mode for Carrying Out the Invention

Hereinafter, the preferred embodiments of the present invention will be

described with reference to the accompanying drawings. Fig. 1 is an illustration of a desirable structure of a metal keypad for a

portable telephone according to the present invention. For the metal keypad for a portable telephone according to the present

invention, as shown on the drawings, PCB (400), on which a dome switch (200)

and LED (300) are set, is located on the bottom as is in the conventional

technique, a metal touch pad (100), in which a thin metal strip (110), a core part

of this invention, and a silicon pad (120) are combined, is located on the top.

The conventional keypad is formed by uniting a key top and a base which

are connected through a connecting part with a front housing, however the

keypad of the present invention is composed of a metal touch pad unifying the

said key top, the base, the connecting part, and the front housing so that it has a

characteristic even thinner than the conventional technique.

Fig. 2 is a cross sectional view of the said metal touch pad (100) in detail. The metal touch pad (100) is composed, in general, of a thin metal strip

(110) and a silicon pad (120), and a thin metal strip (110) and a silicon pad (120)

are combined by compressing joint method using adhesive (130).

The said thin metal strip (110) is composed of a brass slice (111), a nickel

plating part (112), a cobalt plating part (113), and a coating part (114), and the

said silicon pad (120) is jointed with silicon film (122, 123) on the top and the

bottom of PC film (121), and the silicon film (123) on the bottom is formed

including a projecting part (123 ') to contact dome switch on back. The nickel plating part (112) on the top does not exist in the case of

executing the spin process on the top as shown in this example because it is cut

out, but in the case of omitting the spin process, the nickel plating part (112) is

located on the top. Meanwhile, the above thin metal strip (110) has a perforating line (140) in

every fixed position so that it can press a dome switch (200) on the bottom

independently, and the top silicon film (122) of the silicon pad (120) is projected

to the said perforating line (140) so that it prevents any scar caused by sharp

metal slice and it enables the blind to use by a touch sense. The etched part (150) with letters or figures carved by etching is not filled

with silicon film (122) on the top, and is blocked with an epoxy film (115).

Exceptionally, a part such as number 5 put in the center of the touch pad is

formed with a silicon film on the top projected for the disable person as is in a

perforating line.

Fig. 3 is a plane view of the metal touch pad (100) produced according to

an embodiment of the present invention.

The said metal touch pad (100), as shown in the drawings, is composed by

unifying a key top and a front housing which used to be divided into a thin metal

film by forming a line (140) penetrating letters and figures etched and printed on

the etched part (150) according to its position and shape on the top of the metal touch pad (100). At this time, the said etched part (150), as described in the

above, is blocked with a translucent epoxy film (115) to prevent alien matters

from penetrating into the interior and release the light generated form the light

source outward. Fig. 4 is a rear side view of the metal touch pad produced according to an

embodiment of the present invention.

It is formed, as shown in the drawing, by combining a thin silicon film

jointed to the top and the bottom of PC film with a thin metal strip.

Fig. 5 is a procedure showing an embodiment of the manufacturing

method of the metal touch pad for a portable telephone according to the present

invention.

The metal touch pad manufacturing method for a portable telephone according to the present invention is established in general by the thin metal strip processing step, the silicon pad manufacturing step, and the process of combining the two resulting products to complete the metal touch pad.

The present invention has a technical characteristic in the manufacturing

method of the metal touch pad, and the PCB manufacturing process and the

process combining the metal touch pad are the same as the public notice

technology or in the equivalent range. First, for the thin metal strip processing step, letters or figures are etched

in the etching process (S10) after coating ground on the part except letters or

figures to be carved on the brass slice of approx. 0.2mm thick, and adding ferric

chloride solution. Next, the primary plating process (S20) is continued to electrically plate

nickel on the brass slice putting nickel in a positive pole and the brass slice in a

negative pole by using solutions added nickel sulfate, ammonium chloride, boric

acid or nickel chloride.

Then, the translucent formation process (S30) to form thin film goes on by

injecting epoxy resin to the etched part on which letters or figures of the thin

metal strip are etched, which has finished the primary plating process through a

silk screen printing and drying it.

In the next stage, the spin process (S40) is executed to engrave spin

patterns on the surface of the thin metal strip which has finished the translucent

formation process through the spin cutting machine.

After that, the press process (S50) is continued to make the thin metal strip

that can be transformed after finishing the spin process even by the press

machine, and then secondary plating process (S60) using cobalt is executed to

make the metal slice taking on gray. The electro plating process using cobalt is the public notice technology. The thin metal strip which has finished cobalt plating goes through the

surface coating process (S70) to paint the surface of the thin metal strip with a

coating machine and a drier, and the thin metal strip is completed through the

inspection process (S80) to inspect printing, transformation, size, and surface

status of the thin metal strip with magnifier.

On the other hand, all the public notice technology regarding the process

of the exterior in which a certain pattern and a specific color can be applied on

the thin metal strip is applicable to the said thin metal strip processing step as

described in the above. For instance, specific metal can be added through electroforming plating

to add a certain pattern and color to a metal slice, a certain pattern may be formed

on a thin metal strip by etching, or a certain pattern may be inputted on a thin

metal strip by press molding.

Such an appearance processing step is desirable to add after the said

etching process (S 10) .

Next, the silicon pad manufacturing step is composed of the following

stages: the stage printing various colors on the polycarbonate film to be inputted

in the middle of the silicon pad through the film printing process (S90), the stage

of film cutting and punching process (SI 00) to cut and punch PC film on which

colors are printed; the stage of the primary molding process (SI 10) of the back

structure to attach and mold silicon film on the back of the film through heat pressing; the stage of the secondary molding process (SI 20) of the front structure

to coat the silicon film in front of the primary molded product; the stage of the

forging process (SI 30) to forge the exterior of the silicon pad in which the back

and the front are processed with plastic molding; and the stage of the inspection

process (S 140) to inspect related specifications of the silicon pad.

The thin metal strip and the silicon pad that are completed through the thin

metal strip processing step and the silicon pad manufacturing step are combined

through compression joint process (SI 50) using 3M adhesive, finally completed

into the metal touch pad (100). Other processes such as the PCB manufacturing process and the process to

complete the key pad for a portable telephone by combining the metal touch pad

(100) and PCB use the public notice technology on the conventional key pad

manufacturing method for a portable telephone.

Fig. 3 is a plane view of the metal touch pad produced according to an

embodiment of the present invention, and Fig. 4 is a rear side view of the metal

touch pad produced according to an embodiment of the present invention.

Claims

What is claimed is:

1. A metal keypad for a portable telephone having a touch pad unifying a

key top, a base, and a front housing, a printed circuit board (PCB) in which a

fixed contact point in the designated position, a dome switch which is located on

the upper side of the printed circuit board and is contacted to the fixed contact

point on the printed circuit board due to the pressure of the touch pad, and a light

source which is set up among the touch pad and PCB, wherein the touch pad

comprises metal touch pad combining a thin metal strip and resin pad made of

soft material.

2. The metal keypad for a portable telephone of claim 1, wherein the thin

metal strip has characteristics that it is formed between 0.1mm~0.5mm thick, it

has the etched and printed part with letters or figures which is blocked with a

translucent film, and it has a perforating line vertically penetrating the thin metal

strip in the fixed line.

3. The metal keypad for a portable telephone of claim 1 or 2, wherein the

thin metal strip has characteristics that it is processed by metal plating, coating,

and appearance processing.

4. The metal keypad for a portable telephone of claim 1, wherein the resin

pad is combined with resin film on the top and the bottom of the plastic film, and

the resin film on the bottom includes the project part to contact the dome switch.

5. The processing method of a thin metal strip, the method comprising the

processes for: etching process for etching letters and figures on the non-process metal

slice through etching technique; translucent film formation process for forming the translucent film on the

perforating line etched on the said metal slice, the letters, and the figures through

etching technique; surface coating process for painting the surface of the thin metal strip to

prevent fingerprints and scars from occurring and improve durability; and inspection process for inspecting the completion of the thin metal strip

manufactured by the said processes.

6. The processing method of a thin metal strip of claim 5, in case the thin

metal strip is corrosive, wherein further comprising a primary plating process in

which metal plating is executed on the said metal slice and a secondary plating

process in which metal plating is executed on the said metal slice before the

surface coating process after the etching process.

7. The processing method of a thin metal strip of claim 5 or 6, wherein

further comprising a spin process for etching and printing spin patterns with the

fixed slop on surface of the thin metal strip for looking good and a press process

for making the thin metal strip curved by the spin process even after the said

translucent process.

8. The processing method of a thin metal strip of claim 5 or 6, wherein

further comprising appearance processing for adding a specific color or pattern

on the thin metal strip after the etching process.

9. The manufacturing method of resin pad, the method comprising the

processes for: a film printing process for printing various colors on the plastic film; a film cutting and punching process for cutting and punching the color

printed film for meeting mold; a primary molding process for attaching and molding the resin film on the

back of the film by heat pressing; a secondary molding process for coating the resin film on the front of the

product which has finished the primary molding process; a forging process for forging the exterior of the resin pad whose back and

front are molded; and an inspection process for inspecting related specifications of the resin pad.

10. The manufacturing method of metal touch pad comprising a compression

joint process for combining the thin metal strip manufactured by the methods in

any one of claims 5 to 8 and the resin pad manufactured by the method in claim 9

using adhesive.