Membrane circuit board and manufacturing method thereof

Abstract

A membrane circuit board includes a first film substrate, a second film substrate, an insulating spacer substrate and a waterproof structure. The first circuit layer is installed on the first film substrate. A second circuit layer is installed on the second film substrate. The insulating spacer substrate arranged between the first film substrate and the second film substrate. The first circuit layer is arranged between the first film substrate and the insulating spacer substrate. The second circuit layer is arranged between the second film substrate and the insulating spacer substrate. The waterproof structure includes a first welding layer and a second welding layer. The first welding layer is arranged between the first film substrate and the insulating spacer substrate. The second welding layer is arranged between the second film substrate and the insulating spacer substrate.

Claims

1. A membrane circuit board, comprising: a first film substrate, wherein a first circuit layer is installed on the first film substrate; a second film substrate opposed to the first film substrate, wherein a second circuit layer is installed on the second film substrate; an insulating spacer substrate arranged between the first film substrate and the second film substrate, wherein the first circuit layer is arranged between the first film substrate and the insulating spacer substrate, and the second circuit layer is arranged between the second film substrate and the insulating spacer substrate; and a waterproof structure comprising a first welding layer and a second welding layer, wherein the first welding layer is arranged between the first film substrate and the insulating spacer substrate, and the first welding layer is arranged around the first circuit layer, wherein the second welding layer is arranged between the second film substrate and the insulating spacer substrate, and the second welding layer is arranged around the second circuit layer, wherein the first film substrate has a first positioning opening, the insulating spacer substrate has a second positioning opening, and the second film substrate has a third positioning opening, wherein the first positioning opening, the second positioning opening and the third positioning opening are aligned with each other, wherein the first welding layer comprises a first welding part and a second welding part, and the second welding layer comprises a third welding part and a fourth welding part, wherein the first welding part is arranged around the first circuit layer and the second welding part, and the second welding part is arranged around a region between the first positioning opening and the second positioning opening, wherein the third welding part is arranged around the second circuit layer and the fourth welding part, and the fourth welding part is arranged around a region between the second positioning opening and the third positioning opening, wherein the first welding layer further comprises a fifth welding part, and the second welding layer further comprises a sixth welding part, wherein the fifth welding part is arranged between the first circuit layer and the first welding part, the fifth welding part is arranged around the first circuit layer and the second welding part, the sixth welding part is arranged between the second circuit layer and the third welding part, and the sixth welding part is arranged around the second circuit layer and the fourth welding part.

2. The membrane circuit board according to claim 1, wherein after the first film substrate, the insulating spacer substrate and the second film substrate are subjected to an ultrasonic heat melting treatment by an ultrasonic heat melting device, the first welding layer is formed between the first film substrate and the insulating spacer substrate, and the second welding layer is formed between the second film substrate and the insulating spacer substrate.

3. The membrane circuit board according to claim 1, further comprising an anti-slip structure, wherein the anti-slip structure is installed on a surface of the first film substrate away from the insulating spacer substrate, or the anti-slip structure is installed on a surface of the second film substrate away from the insulating spacer substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 schematically illustrates the structure of a membrane circuit board according to an embodiment of the present invention;

(2) FIG. 2 is a schematic cross-sectional view illustrating a portion of the membrane circuit board as shown in FIG. 1 and taken along a viewpoint;

(3) FIG. 3 is a schematic cross-sectional view illustrating a portion of the membrane circuit board as shown in FIG. 1 and taken along another viewpoint;

(4) FIG. 4 is a flowchart illustrating a method of manufacturing a membrane circuit board according to an embodiment of the present invention;

(5) FIG. 5 schematically illustrates an ultrasonic heat melting device according to an embodiment of the present invention; and

(6) FIG. 6 schematically illustrates a portion of the second roller device of the ultrasonic heat melting device as shown in FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(7) Please refer to FIGS. 1, 2 and 3. FIG. 1 schematically illustrates the structure of a membrane circuit board according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating a portion of the membrane circuit board as shown in FIG. 1 and taken along a viewpoint. FIG. 3 is a schematic cross-sectional view illustrating a portion of the membrane circuit board as shown in FIG. 1 and taken along another viewpoint. As shown in FIGS. 1, 2 and 3, the membrane circuit board 1 comprises a first film substrate 11, a second film substrate 12, an insulating spacer substrate 13 and a waterproof structure 14.

(8) A first circuit layer 15 is installed on the first film substrate 11. The first film substrate 11 and the second film substrate 12 are opposed to each other. A second circuit layer 16 is installed on the second film substrate 12. The insulating spacer substrate 13 is arranged between the first film substrate 11 and the second film substrate 12. The first circuit layer 15 is arranged between the first film substrate 11 and the insulating spacer substrate 13. The second circuit layer 16 is arranged between the second film substrate 12 and the insulating spacer substrate 13. The waterproof structure 14 comprises a first welding layer 141 and a second welding layer 142. The first welding layer 141 is arranged between the first film substrate 11 and the insulating spacer substrate 13. Moreover, the first welding layer 141 is arranged around the first circuit layer 15. The second welding layer 142 is arranged between the second film substrate 12 and the insulating spacer substrate 13. Moreover, the second welding layer 142 is arranged around the second circuit layer 16.

(9) Preferably but not exclusively, the first film substrate 11 and the second film substrate 12 are polyester (PET) film substrates. Preferably but not exclusively, the first circuit layer 15 and the second circuit layer 16 are respectively printed on the surfaces of the first film substrate 11 and the second film substrate 12 according to the designated circuit patterns. The membrane circuit board 1 is installed on an external keyboard of a desktop computer (e.g., a keyboard with a PS2 interface or a keyboard with a USB interface) or a built-in keyboard of a notebook computer or a laptop computer. The applications of the membrane circuit board 1 are not restricted. That is, the concepts of the membrane circuit board 1 can be applied to any appropriate electronic product that uses the membrane circuit board 1 as the signal input interface.

(10) The other detailed structure of the membrane circuit board will be described as follows.

(11) Please refer to FIGS. 1, 2 and 3 again. The first film substrate 11 has at least one first positioning opening 110. The insulating spacer substrate 13 has at least one second positioning opening 130. The second film substrate 12 has at least one third positioning opening 120. The first positioning opening 110, the second positioning opening 130 and the third positioning opening 120 are aligned with each other. In this embodiment, the membrane circuit board 1 has plural first positioning openings 110, plural second positioning openings 130 and plural third positioning openings 120. It is noted that the number of these positioning openings is not restricted. When the membrane circuit board 1 is installed on the keyboard device, the membrane circuit board 1 assembled with and positioned in the casing of the keyboard device through these positioning openings.

(12) Please refer to FIGS. 1, 2 and 3 again. The first welding layer 141 comprises a first welding part 1411 and a second welding part 1412. The first welding part 1411 is arranged around the first circuit layer 15 and the second welding part 1412. That is, the first welding part 1411 is located at the outermost region of the membrane circuit board 1 for sealing the gap between the first film substrate 11 and the insulating spacer substrate 13. Consequently, the moisture is not transferred to the first circuit layer 15 through the gap between the first film substrate 11 and the insulating spacer substrate 13. The second welding part 1412 is arranged around the region between the first positioning opening 110 and the second positioning opening 130. The second welding part 1412 is used for sealing the gap between the periphery of the first positioning opening 110 and the periphery of the second positioning opening 130. Consequently, the moisture is not transferred to the first circuit layer 15 through the first positioning opening 110 and the second positioning opening 130.

(13) Please refer to FIGS. 1, 2 and 3 again. The second welding layer 142 comprises a third welding part 1421 and a fourth welding part 1422. The third welding part 1421 is arranged around the second circuit layer 16 and the fourth welding part 1422. That is, the third welding part 1421 is located at the outermost region of the membrane circuit board 1 for sealing the gap between the second film substrate 12 and the insulating spacer substrate 13. Consequently, the moisture is not transferred to the second circuit layer 16 through the gap between the second film substrate 12 and the insulating spacer substrate 13. The fourth welding part 1422 is arranged around the region between the second positioning opening 130 and the third positioning opening 120. The fourth welding part 1422 is used for sealing the gap between the periphery of the second positioning opening 130 and the periphery of the third positioning opening 120. Consequently, the moisture is not transferred to the second circuit layer 16 through the second positioning opening 130 and the third positioning opening 120.

(14) As shown in FIGS. 1 and 2, the first welding layer 141 further comprises a fifth welding part 1413, and the second welding layer 142 further comprises a sixth welding part 1423. The fifth welding part 1413 is arranged between the first circuit layer 15 and the first welding part 1411. The fifth welding part 1413 is arranged around the first circuit layer 15 and the second welding part 1412. The sixth welding part 1423 is arranged between the second circuit layer 16 and the third welding part 1421. The sixth welding part 1423 is arranged around the second circuit layer 16 and the fourth welding part 1422. The fifth welding part 1413 cooperates with the first welding part 1411 to enhance the sealing strength between the first film substrate 11 and the insulating spacer substrate 13. The sixth welding part 1423 cooperates with the third welding part 1421 to enhance the sealing strength between the second film substrate 12 and the insulating spacer substrate 13. It is noted that numerous modifications and alterations may be made while retaining the teachings of the invention. For example, in another embodiment, the fifth welding part 1413 and the sixth welding part 1423 are omitted. Alternatively, at least two welding parts are arranged between the first film substrate 11 and the insulating spacer substrate 13 and between the second film substrate 12 and the insulating spacer substrate 13.

(15) The following aspects should be specially described. After the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 are subjected to an ultrasonic heat melting treatment, the waterproof structure is produced. That is, the first welding layer 141 is formed between the first film substrate 11 and the insulating spacer substrate 13, and the second welding layer 142 is formed between the second film substrate 12 and the insulating spacer substrate 13. The operating principles of the ultrasonic heat melting treatment will be described as follows. Firstly, a sound generator generates a high-frequency signal. Then, a welding head fixed on the ultrasonic heat melting treatment is directly contacted with a plate workpiece made of plastic material (e.g., PET). The high-frequency vibration causes the molecules in the plate workpiece to undergo the violent friction and generate the local high temperature. When the temperature is higher than the melting point of the plastic material, the plastic material is molten. When the molten plastic material is cooled down, the molten plastic material is re-solidified and bonded together to achieve a welding effect. In an embodiment, the welding head of the ultrasonic heat melting treatment is a roller-shaped welding head.

(16) As shown in FIG. 1, the membrane circuit board 1 further comprises an anti-slip structure 17. The anti-slip structure 17 is installed on a surface of the first film substrate 11 away from the insulating spacer substrate 13 (i.e., the outer surface of the first film substrate 11 as shown in FIG. 2). While the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 are subjected to the ultrasonic heat melting treatment by the ultrasonic heat melting device, the welding head of the ultrasonic heat melting device is rolled on the outer surface of the first film substrate 11. Due to the anti-slip structure 17, the friction between the first film substrate 11 and the roller-shaped welding head is increased. Consequently, the roller-shaped welding head is not in the idle state. It is noted that the installation position of the anti-slip structure 17 is not restricted to the outer surface of the first film substrate 11. In another embodiment, the anti-slip structure 17 is installed on a surface of the second film substrate 12 away from the insulating spacer substrate 13 (i.e., the outer surface of the second film substrate 12 as shown in FIG. 2). During the ultrasonic heat melting treatment, the welding head of the ultrasonic heat melting device is rolled on the outer surface of the second film substrate 12.

(17) A method of manufacturing a membrane circuit board of the present invention will be described as follows.

(18) FIG. 4 is a flowchart illustrating a method of manufacturing a membrane circuit board according to an embodiment of the present invention. Hereinafter, the manufacturing method will be described with reference to FIGS. 1, 2, 3 and 4. The manufacturing method comprises the following steps.

(19) Firstly, in a step S1, a first film substrate 11 is provided. A first circuit layer 15 is formed on the first film substrate 11.

(20) In a step S2, an insulating spacer substrate 13 is provided.

(21) In a step S3, a second film substrate 12 is provided. A second circuit layer 16 is formed on the second film substrate 12.

(22) In a step S4, the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 are subjected to an initial positioning treatment. Consequently, the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 are initially aligned with each other.

(23) In a step S5, the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 are subjected to a correcting treatment. Consequently, the relative positions between the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 are finely tuned, and the alignment between these components is more precise.

(24) In a step S6, the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 are subjected to an ultrasonic heat melting treatment. Consequently, a waterproof structure 14 is formed. The waterproof structure 14 comprises a first welding layer 141 and a second welding layer 142. The first welding layer 141 is arranged between the first film substrate 11 and the insulating spacer substrate 13. The second welding layer 142 is arranged between the second film substrate 12 and the insulating spacer substrate 13. Moreover, the first welding layer 141 is arranged around the first circuit layer 15, and the second welding layer 142 is arranged around the second circuit layer 16.

(25) FIG. 5 schematically illustrates an ultrasonic heat melting device according to an embodiment of the present invention. The ultrasonic heat melting device 2 of FIG. 5 is applied to the manufacturing method of FIG. 2. The ultrasonic heat melting device 2 comprises a first roller device 21, a second roller device 22 and a correcting device 23. In the step S4 of FIG. 4, the positioning treatment is performed on the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 by the first roller device 21. In the step S5 of FIG. 4, the correcting treatment is performed on the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 by the correcting device 23. In the step S6 of FIG. 4, the ultrasonic heat melting treatment is performed on the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12 by the second roller device 22.

(26) FIG. 6 schematically illustrates a portion of the second roller device of the ultrasonic heat melting device as shown in FIG. 5. As shown in FIG. 6, the second roller device 22 of the ultrasonic heat melting device 2 comprises a first pattern 221, a second pattern 222 and a third pattern 223. The first pattern 221, the second pattern 222 and the third pattern 223 are protruded from a surface 220 of the second roller device 22. When the ultrasonic heat melting device 2 performs the ultrasonic heat melting treatment on the first film substrate 11, the insulating spacer substrate 13 and the second film substrate 12, the first pattern 221, the second pattern 222 and the third pattern 223 are imprinted on the corresponding positions of the membrane circuit board 1. Consequently, the first welding part 1411, the second welding part 1412, the third welding part 1421, the fourth welding part 1422, the fifth welding part 1413 and the sixth welding part 1423 as shown in FIGS. 1, 2 and 3 are formed. In particular, the first welding part 1411 and the third welding part 1421 are formed through the first pattern 221, the fifth welding part 1413 and the sixth welding part 1423 are formed through the second pattern 222, and the second welding part 1412 and the fourth welding part 1422 are formed through the third pattern 223.

(27) From the above descriptions, the present invention provides a membrane circuit board and a manufacturing method of the membrane circuit board. After a first film substrate, an insulating spacer substrate and a second film substrate of the membrane circuit board are subjected to an ultrasonic heat melting treatment, the first film substrate, the insulating spacer substrate and the second film substrate are combined as a waterproof structure. That is, a first welding layer is formed between the first film substrate and the insulating spacer substrate and arranged around the first circuit layer, and the second welding layer is formed between the second film substrate and the insulating spacer substrate and arranged around the second circuit layer. The first circuit layer and the second welding layer have the function of sealing the membrane circuit board while effectively preventing moisture from entering the internal circuit layers of the membrane circuit board through the space between the film substrates. The manufacturing method of the present invention can produce the membrane circuit board at the increased production efficiency and the reduced production cost. Since the waterproof glue is not used, the manufacturing method of the present invention is environmentally friendly.

(28) While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.