KR20140021783A - Method of making dome switch for button of mobile type equipment - Google Patents

Abstract

Disclosed is a method of making a dome switch for a button of a mobile terminal. The method comprises a step of preparing an FPCB with a central contact and peripheral two contacts that are separated from each other and exposed out; a step of preparing a dome sheet; an adhesive pattern formation step of preparing an adhesive pattern at a region including a peripheral region surrounding the region where a dome switch is formed on at least one among the dome sheet and the FPCB using a printing method; a metal dome preparation step of arranging a metal dome on at least one among the dome sheet and the FPCB; an arrangement step of arranging the dome sheet and the FPCB with a curable synthetic resin and the metal dome that are interposed therebetween; and a step of bonding the dome sheet and the FPCB using the adhesive pattern, wherein the printing method may be screen printing, gravure printing, or offset printing, or the adhesive pattern formation may be performed by spraying an adhesive through a dispenser nozzle. According to the present invention, the method facilitates an accurate positioning and a uniform thickness of an adhesive pattern when forming the adhesive pattern for bonding a dome sheet covering a metal dome to a region of an FPCB where a dome switch exists on an FPCB for a button of a mobile terminal, thereby attaching the dome sheet to the periphery of the dome switch compared with conventional methods, effectively preventing foreign substances from coming into the dome switch, and additionally, reducing the consumption of materials for covering the dome switch. [Reference numerals] (S10) FPCB preparation step; (S20) Adhesive pattern printing step; (S30) Metal dome arrangement step; (S40) Dome sheet alignment step; (S50) Dome sheet attachment step

Description

Method of forming dome switch for button of portable terminal {method of making dome switch for button of mobile type equipment}

The present invention relates to a method of forming a dome switch for a button or a key of a cellular phone or other portable terminal.

A printed circuit board is formed by forming a circuit with a conductive metal layer on an insulator plate or film serving as a base film or a substrate. Patterning operations such as photolithography may be used to form the circuit.

Among printed circuit boards, flexible printed circuit boards (FPCBs) or flexible printed circuit boards, which can be easily bent by forming a base substrate from a soft material such as thin polyimide, are widely used in recent years. . Such flexible printed circuit boards are flexible, easy to deform, lightweight, and thin, and are widely used in portable electronic and communication devices.

The flexible printed circuit board is used alone or in combination with a rigid printed circuit board in the keypad assembly of a mobile phone, and is a tool for connecting an element circuit or switch such as a main board and an LCD window or a camera. It is used a lot as.

By the way, when the FPCB including the dome switch is used for the side key of the cellular phone, the thickness of the cellular phone continues to decrease according to the tendency of light and small size of the cellular phone, and the width of the FPCB also decreases accordingly.

In the case of forming a dome switch for side keys on such narrow FPCB, it is difficult to attach the dome sheet covering the dome switch on the FPCB with a kind of cover film covering the upper part after forming the circuit elements such as the conductor and the switch in the base film. do.

Therefore, the dome sheet is conventionally covered by covering the metal dome only in a predetermined area so that foreign substances or moisture do not enter from the surroundings, thereby widening the dome sheet with adhesive tape and covering the metal dome and the entire surrounding area. A sheet was formed.

However, the work of winding around the dome switch and sealing from the periphery is difficult to automate, and there is a problem of time consuming and manpower cost due to manual work. The cost burden will also increase.

To solve this problem, instead of winding a narrow FPCB into a dome sheet, the area surrounding the FPCB, for example, the perimeter including the metal dome, is covered with the dome sheet to cover the dome switch, and no foreign matter enters the periphery. In order to prevent the adhesive tape or the adhesive layer from being completely enclosed between the FPCB and the dome sheet, it was sought. That is, a method of forming an adhesive tape or an adhesive layer only on the periphery of the dome sheet has been attempted to attach the FPCB surface and the dome sheet only around the metal dome of the FPCB on which the metal dome is placed.

However, when the dome sheet is formed to cover only the dome switch area by using the adhesive layer because the adhesive layer or the independent adhesive layer of the adhesive tape is not formed at the correct position and is not evenly formed, partial sealing occurs. In some cases, foreign substances, moisture, and water were introduced into the gaps, resulting in malfunction of the dome switch. In addition, as the light and small size of the portable terminal proceeds, accurate alignment of the adhesive tape, the dome sheet, and the FPCB is required. However, as these related parts are smaller, the work becomes difficult, and the tape attaching operation is not precisely performed, and thus the possibility of defect is high.

In addition, the adhesive layer is made of a material having high fluidity, and the dome sheet is in place due to factors such as an increase in ambient temperature during use of the portable terminal, an increase in ambient temperature during assembly work, or an external force during operation. The adhesive layer is pushed outwards, which may cause difficulties in subsequent work, induce foreign material inflow, or push the button so that it is not smooth or malfunctions.

Patent Registration No. 10-1153993

The present invention is to solve the problems of the prior art as mentioned above, in the bonding of the dome sheet covering the metal dome in the dome switch area of the FPCB for buttons of the portable terminal, when forming a conventional adhesive layer itself adhesive layer itself Due to the fluidity problem of the adhesive layer, the accuracy of the working position when forming the adhesive layer, and the uniformity of the thickness of the adhesive layer, it is possible to prevent the dome sheet from being in the correct position, causing a problem in the peripheral sealing, and causing an abnormal function of the dome switch. An object of the present invention is to provide a method of forming a dome switch for a portable terminal button.

An object of the present invention is to provide a method for forming a dome switch for a portable terminal button that can stably attach an FPCB and a dome sheet, effectively block foreign material inflow, and reduce the use of materials.

In order to achieve the above object, a method of forming a dome switch for a portable terminal button according to the present invention comprises the steps of: preparing an FPCB exposed with two contacts at a center and a periphery of the dome switch, preparing a dome sheet, and a dome sheet (B) preparing an adhesive pattern using a printing method in an area including at least a peripheral area surrounding an area where a dome switch is formed on one of the FPCBs; and forming a metal dome on either the dome sheet or the FPCB. It comprises a metal dome preparation step, the alignment step to align and overlap the dome sheet and the FPCB in a state where the curable synthetic resin layer and the metal dome interposed, and the step of adhering the dome sheet and the FPCB by using an adhesive material pattern.

In the present invention, the adhesive pattern may be formed of a thermosetting adhesive or a photocurable adhesive. In this case, in the step of adhering, the adhesive pattern is not attempted by simple contact but is thermally cured by heating or photocuring by light irradiation.

In the present invention, printing may be performed by a screen printing method, a gravure printing method, or an offset printing method.

In the present invention, printing may be used in a broad sense including various replicas and in a manner using a dispenser.

On the other hand, in order to form a uniform thickness of the adhesive layer or adhesive pattern formed by the printing method in the method of the present invention, in the printing system described above, it is necessary to adjust the viscosity of the sol phase or liquid adhesive sprayed or transferred through the nozzle instead of the conventional ink. need.

In the method of the present invention, the FPCBs may be processed separately, but a plurality of FPCBs are processed at one time using the assisting tool, and even in the adhesive pattern forming step, the adhesive patterns for the plurality of FPCBs may be formed at once through printing. In addition, in the alignment step for aligning the dome sheet and the FPCB, and the bonding step for bonding, the work is performed on the plurality of FPCBs at once, and after this operation, the step of separating the individual FPCBs through the punching process may be further performed.

In order to make the adhesive pattern formation in the method of the present invention, the material forming the adhesive pattern should be used in a liquid or sol phase similar to the printing ink, and may be changed into a gel or solid phase through a subsequent process. .

According to the present invention, in forming an adhesive layer for joining a dome sheet covering a metal dome in a dome switch region of a button FPCB of a portable terminal, it is easy to realize a precise adhesive layer pattern position and a uniform pattern thickness, compared to a conventional dome. It is possible to stably attach the dome sheet around the switch, effectively block foreign matter from entering the dome switch, and reduce the use of materials for covering the dome switch.

The present invention facilitates mass production by facilitating multiple FPCB operations at the same time using mechanization for alignment and attachment in dome switch formation and dome sheet attachment.

1 is a schematic cross-sectional view showing the structure of a dome switch part according to an embodiment of the present invention;
2 is a flowchart illustrating an embodiment of the method of the present invention;
Fig. 3 is a conceptual diagram showing a state where a plurality of FPCBs for a mobile phone side key are placed together on a support in one step of implementing the method of the present invention.
4 is a conceptual diagram illustrating dome sheets arranged in a matrix corresponding to the FPCB of FIG. 3 and having a curable adhesive layer on one surface thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Referring to FIG. 1, in a FPCB for a mobile phone side key in which a conductive pattern 20 is formed on a base film 10, two contacts 21 and 23 at a center and a periphery of a dome switch are exposed to be spaced apart from each other. (21, 23) The convex shape of the metal dome 30 is installed in contact with the peripheral contact 21, but not the center contact 23, the dome sheet 40 covering the metal dome 30 is The outer periphery of the metal dome is coupled to the FPCB via the adhesive layer 50 between the base film 10 at the outer peripheral portion of the FPCB.

Here, both the base film 10 and the dome sheet 40 for the FPCB 100 may be made of a polymer resin, and as the adhesive layer 50, various materials from adhesives to thermosetting adhesives used by dissolving in a solvent, Adhesives of various uses may be used.

The adhesive layer 50 needs to be made of a material having good adhesion between both the FPCB base film and the dome sheet, and the FPCB base film or dome sheet may be made of polyimide (PI) or Often made of PET.

When the thermosetting adhesive is used for the adhesive layer 50, the adhesive layer may be hardened by applying heat using a jig of the heat fusion machine in a required portion including the dome switch peripheral region.

2 shows a flowchart of one embodiment of the method of the present invention.

In this embodiment, first, an FPCB having two dome switches exposed is formed (S10). This can be done in the same manner as the process of forming an FPCB for a mobile phone side key. For example, a base film is prepared, a metal layer is formed on the base film, a metal pattern is formed through photoresist coating, pattern exposure using a mask, development, and cleaning, and a coverlay film is laminated as necessary. The pattern forms to the outside. For example, the two contacts forming the dome switch are also formed to be exposed to the outside.

Next, in the adhesive pattern printing step (S20), a liquid or sol-like thermosetting adhesive pattern is formed by using a printing technique to cover a predetermined region including a region surrounding the outer peripheral portion of the two contact points above the FPCB.

In the present invention, printing may be performed by a general transfer method such as a screen printing method, a gravure printing method, or an offset printing method, or a photorealistic method using a dispenser. Printing is used in a broad sense including various reproductions, and the method of using a dispenser will be understood in a broad sense.

In the case of using a dispenser, in more detail, a direct dispenser method in which the adhesive is applied directly to the FPCB or dome sheet to be the object by using the dispenser, or the adhesive is applied through the dispenser to the intermediate means, and the adhesive pattern is transferred from the medium to the object. Normal printing can be done.

The dispenser can be used in a variety of ways from having a single adhesive nozzle to having a large number of nozzles, from a simple nozzle method to a method in which multiple nozzles have a matrix arrangement, such as the head of an inkjet printer.

The dispenser device holds the object on a plane, installs a stationary X-axis rod in one of two orthogonal axes, and installs a Y-axis rod extending in the other axial direction where one end is fixed to move along this rod. In addition, by installing a nozzle or a head to be movable along the Y-axis rod, it can be made in the X, Y plotter method that can draw the pattern on the X, Y plane of the object, it is somewhat modified to the object as in a conventional inkjet printer While moving in one direction, it is also possible to install a rod in a direction orthogonal to this direction, and to install a nozzle or head moving on the rod to draw a pattern on a desired portion.

Opening and closing of nozzles for spraying the adhesive (hereinafter, used in a broad sense including a case where a plurality of nozzles are arranged in a matrix such as a printer head) and movement of the nozzles on the X and Y axes are usually controlled by a computer device. This form is conceptually equivalent to spraying adhesive at a certain position on a substrate by inserting an adhesive instead of ink in an inkjet printer and creating a pattern using a drawing program such as a CAD program on a computer. By precisely adjusting the nozzle spraying amount, precise and uniform pattern formation is possible not only in the position and line width of the adhesive pattern but also in the thickness of the adhesive pattern.

On the other hand, in order to form a uniform thickness of the adhesive layer or the adhesive pattern formed by the printing method in the method of the present invention to adjust the viscosity of the sol-like or liquid adhesive is sprayed through a nozzle instead of ink or transferred in the printing method in the printing system described above It is necessary to do

For example, if the viscosity is too high, difficulties may arise when spraying the adhesive pattern onto the FPCB or dome sheet with the dispenser nozzle, resulting in frequent device failures and difficult control.

If the viscosity is too low, spraying the adhesive onto the object may cause the adhesive to bleed, bounce or spread on the surface of the FPCB or dome sheet, causing the pattern to collapse, and when pressure is applied to overlap the FPCB and dome sheet through the adhesive pattern, Spreading can make it difficult to form an accurate and uniform adhesive layer.

As a method of eliminating this problem, a large amount of solvent may be used to reduce the viscosity during spraying, but a volatile solvent may be used as the adhesive solvent, and a method of controlling the sprayed adhesive temperature may also be used.

In order to form the adhesive pattern easily and precisely, the adhesive viscosity is kept relatively low in the printing step for forming the pattern, and the pattern can be stably maintained after forming the pattern. It is also possible to use.

In this case, once the photopolymerizable composition is sprayed onto the FPCB or the dome sheet by using a dispenser to form an adhesive pattern, and the photopolymerization reaction is performed through light irradiation, the pattern may be changed into a thermosetting adhesive pattern having a high viscosity. Follow-up work in a stable pattern state can solve the problems caused by pattern defects in the follow-up process.

After the adhesive pattern is formed by printing, the metal dome arrangement step (S30) of positioning the metal dome according to the contact position on the FPCB while the dome switch contact is still exposed is performed. Naturally, the metal dome is aligned so that the periphery is positioned at the periphery contact position between the two contacts, and the convex up center part is positioned above the central contact point location between the two contacts.

Next, in the dome sheet alignment step (S40) and the attachment step (S50), the dome sheet prepared in advance is aligned and closely adhered to the FPCB while the metal dome is arranged. The dome sheet is stably fixed to the FPCB by the thermosetting adhesive pattern.

Next, the thermosetting adhesive is cured by applying heat in the outer region surrounding the peripheral contact using the jig of the heat welder above the dome sheet. The heating temperature and time using the heat welding machine may vary depending on the material and thickness of the thermosetting film and the dome sheet state. As a result, the thermosetting adhesive is modified to form a thermosetting adhesive layer with strong adhesion to the dome sheet and the base film of the FPCB.

Since the adhesive layer in the hardened state maintains no fluidity and maintains a stable shape, foreign substances flow between the metal dome and the contact in the dome switch structure that forms the buttons of the portable terminal, or moisture may cause the buttons to malfunction or cause button switch life. The problems of shortening can be prevented.

In the above embodiment, a thermosetting adhesive pattern, a metal dome, and a dome sheet are sequentially arranged and attached on the FPCB, and a dome switch structure is formed to heat the necessary portion to seal the dome switch part, but each of the thermosetting film and the metal dome is first placed on the FPCB. Whether to be bonded and bonded to the dome sheet, to be bonded first to the dome sheet side and FPCB, or which of the thermosetting film and the metal dome to be bonded first can be varied as necessary.

In such an embodiment, the adhesive layer may be formed in a pattern having an accurate width at the exact position of the FPCB or the dome sheet by using a sophisticated printing technique, and once printed using a sol or liquid precursor composition as an ink, The pattern can be made into a gel state by polymerization, and the form and area | region of the pattern can be fixed.

Therefore, it is possible to reduce the problems caused by the breakdown or spreading of the pattern in the subsequent work. Finally, the FPCB and the dome sheet are stably fixed using hardening, and the foreign matter or moisture is sealed by sealing the dome switch. It is possible to prevent the intrusion and the resulting malfunctions, failures.

When the jig is bonded to the heat welding machine for thermal curing and hardened by contacting with the corresponding part, the jig melts or partially heats the thermosetting adhesive layer between the dome sheet and the insulating base of the FPCB in a region forming a closed curve outside the contact of the periphery of the dome switch. In the molten state, the width of the closed curve can be made narrow and precise, for example about 0.3 to 1mm. This figure may be achieved by forming a wider printing pattern and precisely adjusting the line width of the jig pattern, but the jig pattern may have a margin to precisely form a pattern width printed by the thermosetting adhesive precursor composition so that the jig pattern covers the entire printing pattern. It can also be done by.

When contacting the heat jig's heating jig to the FPCB and dome sheet alignment for thermosetting, pressurization pressure, temperature and time are applied to prevent the thermosetting adhesive layer from spreading to other areas instantaneously, or to prevent melting from spreading in neighboring areas. It is necessary to adjust. In addition, it is necessary to make the floor as flat as possible in order to even the pressure in the operation of contacting the jig to even the degree of thermal curing.

On the other hand, it is also possible to leave the FPCB and the dome sheet alignment body in a constant temperature oven for a certain time so that curing is performed in both the thermosetting adhesive layers without using a jig separately.

On the other hand, the FPCB for the side keys described as an example in the above embodiment is very small, and the dome sheet or other cover attached thereto is very small, and the fused portion is only the periphery of the dome sheet, so that expensive and precise printing equipment or dispenser Rather than processing parts one by one with equipment, multiple FPCBs 100 are arranged in a matrix form, such as by using an auxiliary die 110, as shown in FIG. 5, or a dome like the dome sheet 200 arrangement of FIG. It is desirable to print the adhesive layer or dispense dispenser at a time by aligning the sheets by the number that fits the FPCB, which is typically premised in the present invention.

In this case, the adhesion of the dome sheet on which the metal dome or the adhesive pattern is formed to the FPCB is also preferably prepared by combining the FPCB at the same number as the dome sheet 200 alignment form of FIG. Do.

At this time, when arranging a plurality of FPCBs in a matrix form, as shown in FIG. 5, the regions A to be attached to the tape are arranged together on the auxiliary die 110, and the regions B to which the tape is not attached are arranged. Is placed on the outside, the dome sheet 200 is arranged in a matrix form in accordance with the region A of Figure 5, for example, through the printing operation to form a thermosetting adhesive layer by printing on the dome sheet of Figure 6 together This makes it easy to align and reduce the inconvenience caused by the B area.

Then, when a plurality of side key FPCBs are operated at the same time as in the states of Figs. 5 and 6, the separation operation (breaking) is followed because each FPCB must be separated in order to be used in the portable terminal.

In the above described the present invention mainly through a limited embodiment associated with the FPCB for the side key of the mobile phone, by printing using a composition containing a photopolymerizable material as the adhesive as a thermosetting adhesive precursor, this helps to understand the present invention The invention has been described by way of example only, and the invention is not limited to these specific embodiments. That is, one of ordinary skill in the art to which the present invention pertains may make various modifications or applications based on the present invention, and such modifications and applications belong to the appended claims.

10: base film 20: contact
30: metal dome 40: dome sheet
50: adhesive layer 100: FPCB
110: auxiliary die

Claims (5)

Preparing an exposed FPCB with the two contacts at the center and the periphery of the dome switch spaced apart;
Preparing the dome sheet,
An adhesive pattern forming step of preparing an adhesive pattern using a printing method in a region including a periphery surrounding an area where at least one dome switch is formed on either the dome sheet or the FPCB;
A metal dome preparation step of arranging and combining a metal dome with either the dome sheet or the FPCB;
An alignment step of aligning and overlapping the dome sheet and the FPCB with the adhesive pattern and the metal dome interposed therebetween,
And bonding the dome sheet and the FPCB using the adhesive material pattern. The method of claim 1,
The printing method of the adhesive pattern forming step is a method of forming a dome switch for a portable terminal button, characterized in that one of screen printing, gravure printing, offset printing. The method of claim 1,
The printing method of the adhesive pattern forming step is a direct dispenser method for forming a pattern by spraying the adhesive directly to any one of the dome sheet or the FPCB using a dispenser having one or more nozzles. How to form a dome switch. The method according to any one of claims 1 to 3,
In the preparing of the FPCB, a plurality of the FPCBs are arranged in a matrix form in a matrix, and prepared.
In the preparing of the dome sheet, a plurality of dome sheets corresponding to the plurality of FPCBs may be prepared in a matrix form.
In the adhesive pattern forming step, the dome switch forming method for a portable terminal button characterized in that the printing is performed at a time on the plurality of FPCB or the plurality of dome sheets. The method according to any one of claims 1 to 3,
In the adhesive pattern forming step, an adhesive pattern is formed of a sol or a liquid material, which is a composition containing a photopolymerizable material which is a precursor of a thermosetting adhesive by a printing method, and a thermosetting adhesive pattern is formed through light irradiation on the adhesive pattern. A method of forming a dome switch for a portable terminal button.

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