Heater structure

Abstract

To provide a planar heater structure that is connected to a flexible printed circuit using an anisotropic conductive film and is capable of efficiently generating heat. [Solution] The heater portion 30 of the heater structure 10 is connected between the main portions 401 and 421 of two thick-film busbars 40 and 42. The thick-film busbars 40 and 42 each have first connection portions 403 and 423. The anisotropic conductive film 50 has two second connection portions 501 and 503. Each of the two thin-film connection portions 60 and 62 connects the corresponding first connection portions 403 and 423 to the corresponding second connection portions 501 and 503. The thick-film busbars 40 and 42 are not in direct contact with the anisotropic conductive film 50. The thin-film connection portion 60 is covered by the insulating coat 70 and the anisotropic conductive film 50 so as not to be exposed, except for the connection portion with the thick-film busbars 40 and 42.

Description

Technical Field

[0001] The present invention relates to a heater structure, and particularly to a planar heater structure.

Background Art

[0002] As a method for connecting a flexible printed circuit (FPC) to a circuit board, a method using an anisotropic conductive film (ACF) is known. Such a method is disclosed, for example, in Patent Document 1.

[0003] The method disclosed in Patent Document 1 is performed as shown in FIG. 9. First, a liquid crystal display panel 110, an anisotropic conductive film 120, and a flexible substrate 130 are placed on a crimping stage 100. At this time, the anisotropic conductive film 120 is positioned between the electrode terminals 111 of the liquid crystal display panel 110 and the electrode terminals 131 of the flexible substrate 130. Next, the flexible substrate 130, the anisotropic conductive film 120, and the liquid crystal display panel 110 are heated while being pressed by a heater bar 140 via a cushion material 150. Thereby, the anisotropic conductive film 120 mechanically connects the liquid crystal display panel 110 and the flexible substrate 130, and also electrically connects between the electrode terminals 111 of the liquid crystal display panel 110 and the electrode terminals 131 of the flexible substrate 130.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] There is a demand to connect a flexible printed circuit to the heater portion of a planar heater structure using an anisotropic conductive film. On the other hand, in order to efficiently generate heat in a planar heater structure, the electrical resistance must be reduced in the parts other than the heating element.

[0006] Therefore, the present invention aims to provide a planar heater structure that is connected to a flexible printed circuit using an anisotropic conductive film and is capable of generating heat efficiently. [Means for solving the problem]

[0007] The present invention provides a planar heater structure comprising a heater section, two thick busbars, an anisotropic conductive film, two thin film connecting sections, and an insulating coating, as a first heater structure. Each of the two thick film busbars has a main portion and a first connecting portion. The main portions of the two thick-film busbars are located apart from each other. The heater section is spread out in a planar shape and is connected between the main portions of the two thick film busbars. The anisotropic conductive film has two second connection portions, The two thin film connecting portions correspond to the first connecting portion of the thick film busbar, and also correspond to the two second connecting portions, Each of the two thin-film connecting portions connects the corresponding first connecting portion and the corresponding second connecting portion. The thick busbar is not in direct contact with the anisotropic conductive film. The thin film connection portion, except for the connection portion with the thick film busbar, is covered by the insulating coating and the anisotropic conductive film so as not to be exposed. A heater structure is provided.

[0008] Furthermore, the present invention provides a second heater structure, which is a first heater structure, The heater structure further includes a sealing material that covers the thick film busbar so that the thick film busbar is not exposed. A heater structure is provided.

[0009] Furthermore, the present invention provides a third heater structure, which is a first heater structure, The first connecting portion of the thick film busbar extends in the first horizontal direction, The thin film connecting portion protrudes from the first connecting portion in a second horizontal direction perpendicular to the first horizontal direction when viewed from above. A heater structure is provided.

[0010] Furthermore, the present invention provides a fourth heater structure, which is the first heater structure, The heater structure further comprises two thin-film busbars, The thin film busbars are each located below the thick film busbars and connect the thick film busbars to the heater section. The thin film connection portion is formed integrally with the thin film busbar. A heater structure is provided. [Effects of the Invention]

[0011] In the heater structure of the present invention, the heater portion is connected between the main portions of the thick-film busbars. By using thick-film busbars, the heater structure can generate heat efficiently. Furthermore, in the heater structure of the present invention, each thin-film connection portion connects the first connection portion of the corresponding thick-film busbar to the second connection portion of the corresponding anisotropic conductive film. This allows the flexible printed circuit to be connected to the heater structure without the anisotropic conductive film directly contacting the thick-film busbars. As a result, the flexible printed circuit can be separated from the thick-film busbars, making it easy and reliable to prevent corrosion of the thick-film busbars. [Brief explanation of the drawing]

[0012] [Figure 1] This is a transparent plan view showing a heater structure according to one embodiment of the present invention. [Figure 2] FIG. 1 is a plan view for explaining the first step in the method for manufacturing the heater structure of FIG. 1. All elements are drawn as opaque elements. [Figure 3] FIG. 1 is a plan view for explaining the second step in the method for manufacturing the heater structure of FIG. 1. All elements are drawn as opaque elements. [Figure 4] FIG. 1 is a plan view for explaining the third step in the method for manufacturing the heater structure of FIG. 1. All elements are drawn as opaque elements. [Figure 5] FIG. 1 is a plan view for explaining the fourth step in the method for manufacturing the heater structure of FIG. 1. All elements are drawn as opaque elements. [Figure 6] FIG. 1 is a plan view for explaining the fifth step in the method for manufacturing the heater structure of FIG. 1. All elements are drawn as opaque elements. [Figure 7] FIG. 1 is a plan view for explaining the sixth step in the method for manufacturing the heater structure of FIG. 1. All elements are drawn as opaque elements. [Figure 8] FIG. 7 is a schematic diagram showing the structure along the A-A line cross-section of the heater structure and the flexible printed circuit of FIG. 7. The size and aspect ratio of each element do not match those of FIG. 7. A part of the electrode of the flexible printed circuit is shown by a broken line. [Figure 9] FIG. 1 is a diagram for explaining a method of connecting a circuit board and a flexible printed circuit (FPC) in Patent Document 1. MODE FOR CARRYING OUT THE INVENTION

[0013] Referring to FIG. 1, a heater structure 10 according to an embodiment of the present invention is a planar heater structure. The heater structure 10 according to the present embodiment includes a base material 20, a heater portion 30, two thick film bus bars 40 and 42, an anisotropic conductive film 50, two thin film connection portions 60 and 62, and an insulating coat 70. In the present embodiment, the heater structure 10 further includes two thin film bus bars 64 and 66, an extended insulating coat 72, and sealing materials 80 and 82.

[0014] As shown in FIG. 1, the base material 20 has a rectangular shape in a top view. In the present embodiment, the vertical direction is the Z direction. The +Z direction is upward, and the -Z direction is downward. The base material 20 is, for example, a film made of an insulating resin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), cycloolefin polymer (COP), or polyimide. In the present embodiment, the base material 20 has flexibility. Further, in the present embodiment, the base material 20 is transparent. However, the present invention is not limited thereto. The base material 20 may have rigidity. Nevertheless, when the base material 20 has flexibility, the heater structure 10 can be used after being processed into a curved shape, or can be used by being attached to a structure having a curved shape. Further, the base material 20 may be opaque. The base material 20 may also be made of glass. Furthermore, the shape of the base material 20 may be circular, trapezoidal, or the like.

[0015] As shown in FIG. 1 and FIG. 2, the heater portion 30 is formed on the surface of the base material 20 and spreads in a planar shape. In the present embodiment, the heater portion 30 is a mesh-shaped metal thin film. As a material for the metal thin film, Au, Ag, Al, Cu, or the like can be used. However, the present invention is not limited thereto. The heater portion 30 only needs to generate heat when energized, and may be a transparent conductive film such as an ITO film. Furthermore, the heater portion 30 may have a shape other than a mesh shape, such as a stripe shape or a rectangular shape.

[0016] As can be seen from Figures 1 and 4, the thick-film busbars 40 and 42 each have main portions 401 and 421 and first connecting portions 403 and 423, respectively. In this embodiment, the thick-film busbars 40 and 42 further have connecting portions 405 and 425, respectively. The main portions 401 and 421, the connecting portions 405 and 425, and the first connecting portions 403 and 423 of the thick-film busbars 40 and 42 are integrally formed using the same material. For example, the thick-film busbars 40 and 42 can be formed by screen printing using a conductive paste containing Au, Ag, Pd, Ni, or Cu.

[0017] As shown in Figures 1 and 4, the thick film busbars 40 and 42 are separated from each other in the first horizontal direction. The main portions 401 and 421 of the thick film busbars 40 and 42 extend in a second horizontal direction perpendicular to the first horizontal direction. The main portions 401 and 421 are separated from each other in the first horizontal direction, and the heater portion 30 is positioned between them. In this embodiment, the first horizontal direction is the X direction, and the second horizontal direction is the Y direction.

[0018] As shown in Figures 1 and 4, the first connecting portions 403 and 423 of the thick film busbars 40 and 42 extend in the first horizontal direction. The connecting portions 405 and 425 extend in the first horizontal direction and connect one end of the main portions 401 and 421 to one end of the first connecting portions 403 and 423.

[0019] As can be seen from Figures 1 and 5, the anisotropic conductive film 50 is ribbon-shaped and extends in a first horizontal direction. The anisotropic conductive film 50 is a film in which conductive particles are dispersed in a thermosetting resin. As conductive particles, resin particles plated with Ni, Au, Pd, etc., or metal particles such as Ni, Au, Pd, etc. can be used. In this embodiment, the anisotropic conductive film 50 has two second connecting portions 501 and 503. In this embodiment, the second connecting portions 501 and 503 are located at both ends of the anisotropic conductive film 50. However, the present invention is not limited thereto. The heater structure 10 of the present invention may have two anisotropic conductive films corresponding to the two second connecting portions 501 and 503, respectively, instead of the anisotropic conductive film 50.

[0020] As shown in Figures 1 and 2, each of the two thin-film connecting sections 60 and 62 is formed in a substantially rectangular shape using a conductive thin film. In this embodiment, the thin-film connecting sections 60 and 62 are formed simultaneously using the same material (metal thin film) as the heater section 30.

[0021] As shown in Figures 1 and 2, the thin film connectors 60 and 62 are spaced apart from each other in the first horizontal direction. The thin film connectors 60 and 62 correspond to the first connectors 403 and 423 of the thick film busbars 40 and 42, respectively, and also to the second connectors 501 and 503 of the anisotropic conductive film 50, respectively. Specifically, the thin film connectors 60 and 62 each have a comb-shaped front end portion 601 and 621 located at the front end and a base portion 603 and 623 located at the rear end. In this embodiment, the front-rear direction coincides with the second horizontal direction. The +Y direction is forward, and the -Y direction is rear.

[0022] As can be seen from Figure 1, the front ends 601 and 621 of the thin film connectors 60 and 62 overlap with the second connectors 501 and 503 of the anisotropic conductive film 50, respectively, when viewed from above, and the bases 603 and 623 overlap with the first connectors 403 and 423 of the thick film busbars 40 and 42, respectively, when viewed from above. In this embodiment, the thin film connectors 60 and 62 protrude from the first connectors 403 and 423 of the thick film busbars 40 and 42 in a second horizontal direction when viewed from above. In other words, in this embodiment, the thin film connectors 60 and 62 protrude in a direction perpendicular to the direction in which the first connectors 403 and 423 extend. However, the present invention is not limited thereto. The thin film connectors 60 and 62 may also protrude from the first connectors 403 and 423 of the thick film busbars 40 and 42 in a first horizontal direction when viewed from above. In other words, the thin film connectors 60 and 62 may protrude in the direction in which the first connectors 403 and 423 extend. However, if the thin film connectors 60 and 62 protrude in a direction perpendicular to the direction in which the first connectors 403 and 423 extend, it is easier to increase the contact area with the second connectors 501 and 503. By increasing the contact area, electrical resistance can be reduced and the heating efficiency of the heater structure 10 can be increased.

[0023] As shown in Figures 1 and 2, the two thin-film connectors 60 and 62 are connected to thin-film busbars 64 and 66, respectively. In this embodiment, the thin-film busbars 64 and 66 are formed simultaneously and integrally with the heater section 30 and the thin-film connectors 60 and 62 using the same material.

[0024] As can be seen from Figures 1, 2, and 4, the shapes of the thin-film busbars 64 and 66 are similar to the shapes of the thick-film busbars 40 and 42, respectively. More specifically, as shown in Figures 1 and 2, each of the thin-film busbars 64 and 66 has a main section 641, 661 and an extension section 643, 663.

[0025] As shown in Figures 1 and 2, the main portions 641 and 661 of the thin-film busbars 64 and 66 extend in a first horizontal direction and are connected to the heater portion 30. The extensions 643 and 663 of the thin-film busbars 64 and 66 extend in a second horizontal direction. The main portions 641 and 661 of the thin-film busbars 64 and 66 are located below the main portions 401 and 421 of the thick-film busbars 40 and 42, respectively. The extensions 643 and 663 of the thin-film busbars 64 and 66 are located below the connecting portions 405 and 425 of the thick-film busbars 40 and 42, respectively. The main portions 641 and 661 of the thin-film busbars 64 and 66 electrically connect the main portions 401 and 421 of the thick-film busbars 40 and 42 to the heater portion 30. By using thick-film busbars 40 and 42, the electrical resistance of the power supply path to the heater section 30 can be reduced, and the heating efficiency of the heater structure 10 can be improved.

[0026] As shown in Figures 1 and 3, the insulating coat 70 is positioned to cross the thin film connection portions 60 and 62 in the first horizontal direction. The front ends 601 and 621 of the thin film connection portions 60 and 62 are located in front of the insulating coat 70, and the bases 603 and 623 of the thin film connection portions 60 and 62 are located behind the insulating coat 70. The extended insulating coat 72 is positioned to cover the entire heater portion 30. The insulating coat 70 and the extended insulating coat 72 are also called overcoats and are made of thermosetting resin, photocurable resin, etc.

[0027] As can be seen from Figures 1, 6, and 7, the encapsulants 80 and 82 are formed to cover the thick-film busbars 40 and 42, respectively. The encapsulants 80 and 82 are made of thermosetting resin, photocurable resin, etc. The encapsulants 80 and 82 are made of the same or different material as the insulating coat 70 and the extended insulating coat 72.

[0028] The manufacturing method of the heater structure 10 will be described below with reference to Figures 2 to 8, and the structure of the heater structure 10 will be further explained.

[0029] First, as shown in Figure 2, the heater portion 30, thin film connectors 60, 62, and thin film busbars 64, 66 are formed on the surface of the substrate 20. The heater portion 30, thin film connectors 60, 62, and thin film busbars 64, 66 can be formed simultaneously by patterning a metal thin film formed on the substrate 20. In this invention, the thin film busbars 64, 66 are not essential. However, the thin film busbars 64, 66 facilitate the formation of the thick film busbars 40, 42 and help improve the reliability of the electrical connection between the thick film busbars 40, 42 and the heater portion 30.

[0030] Next, as shown in Figure 3, an insulating coat 70 and an extended insulating coat 72 are formed. The insulating coat 70 and the extended insulating coat 72 can be formed simultaneously by forming an insulating film and patterning it. The insulating coat 70 may be divided into two parts corresponding to the thin film connection portions 60 and 62, respectively.

[0031] Next, as shown in Figure 4, thick-film busbars 40 and 42 are formed. The thick-film busbars 40 and 42 can be formed simultaneously by screen printing using conductive paste or the like. The thick-film busbars 40 and 42 are formed so as to overlap with the base portions 603 and 623 of the thin-film busbars 64 and 66 and the thin-film connectors 60 and 62. As a result, the first connectors 403 and 423 of the thick-film busbars 40 and 42 are electrically connected to the thin-film connectors 60 and 62. The thick-film busbars 40 and 42 are also connected to the heater portion 30 via the thin-film busbars 64 and 66. However, the present invention is not limited to this. The thick-film busbars 40 and 42 may also be directly connected to the heater portion 30. In any case, the heater portion 30 is connected between the main portions 401 and 421 of the two thick-film busbars 40 and 42.

[0032] Next, as shown in Figure 5, the anisotropic conductive film 50 is attached to cover the front ends 601 and 621 of the thin film connection portions 60 and 62. The anisotropic conductive film 50 is attached so as to partially overlap with the insulating coat 70. As mentioned above, instead of the anisotropic conductive film 50, two anisotropic conductive films corresponding to the thin film connection portions 60 and 62 can be used, respectively. However, in order to avoid an increase in the number of parts and the number of work steps, it is preferable to use a single anisotropic conductive film 50.

[0033] Next, as shown in Figure 6, the flexible printed circuit (FPC) 90 is connected and fixed to the heater structure 10 using the anisotropic conductive film 50. Specifically, the flexible printed circuit (FPC) 90 is placed on the anisotropic conductive film 50 and heated while being pressed toward the substrate 20.

[0034] Finally, as shown in Figure 7, sealing materials 80 and 82 are formed to cover the thick-film busbars 40 and 42, respectively. The sealing materials 80 and 82 cover the thick-film busbars 40 and 42 so that they are not exposed. The sealing materials 80 and 82 act as moisture-proof or waterproof materials, preventing corrosion of the thick-film busbars 40 and 42. In this way, the heater structure 10 to which the flexible printed circuit (FPC) 90 is connected is completed.

[0035] As can be seen from Figure 8, in the completed heater structure 10, the thin film connector 60 connects the first connector 403 of the thick film busbar 40 to the second connector 501 of the anisotropic conductive film 50. Similarly, the thin film connector 62 connects the first connector 423 of the thick film busbar 40 to the second connector 503 of the anisotropic conductive film 50. In this way, the thin film connectors 60 and 62 connect the corresponding first connectors 403 and 423 to the corresponding second connectors 501 and 503, respectively.

[0036] As can be seen from Figure 8, by using thin-film connectors 60 and 62, the thick-film busbars 40 and 42 are separated from the anisotropic conductive film 50 and do not come into direct contact with it. As a result, the flexible printed circuit (FPC) 90 connected to the heater structure 10 does not overlap with the thick-film busbars 40 and 42 when viewed from above. With this configuration, the flexible printed circuit (FPC) 90 does not interfere with the formation of the sealing material 80 and 82. Therefore, the sealing material 80 and 82 can completely cover the thick-film busbars 40 and 42, respectively, and corrosion of the thick-film busbars 40 and 42 can be prevented. In addition, the thin-film connectors 60 and 62 are covered by the insulating coat 70 and the anisotropic conductive film 50, except for the connection points with the thick-film busbars 40 and 42, so as not to be exposed. In particular, due to its thickness, the anisotropic conductive film 50 covers the edges of the thin film connectors 60 and 62 at the connection points between the thin film connectors 60 and 62 and the flexible printed circuit (FPC) 90, completely sealing these connections. Therefore, corrosion of the thin film connectors 60 and 62 can also be prevented. Since corrosion of the thick film busbars 40 and 42 and the thin film connectors 60 and 62 is prevented, an increase in electrical resistance due to corrosion can be prevented, and the high heating efficiency of the heater structure 10 can be maintained.

[0037] The present invention has been described above with reference to embodiments, but the present invention is not limited to the embodiments described above, and various modifications and changes are possible without departing from the spirit of the present invention. For example, in the above embodiments, the thick film busbars 40 and 42 have connecting portions 405 and 425, and their shape is L-shaped. However, the present invention is not limited thereto. The thick film busbars 40 and 42 do not have connecting portions 405 and 425, and their shape is I-shaped. In that case, the thin film connecting portions 60 and 62 may protrude in the first horizontal direction from the first connecting portions 403 and 423 of the thick film busbars 40 and 42 that extend in the second horizontal direction, or they may protrude in the second horizontal direction. However, if the thin film connecting portions 60 and 62 protrude in a direction perpendicular to the direction in which the first connecting portions 403 and 423 extend, it is easier to increase the contact area with the second connecting portions 501 and 503. In this case, protruding in the second horizontal direction makes it easier to increase the contact area with the second connecting portions 501 and 503. By increasing the contact area, electrical resistance can be reduced and the heating efficiency of the heater structure 10 can be increased.

[0038] Furthermore, in the above embodiment, the thick-film busbars 40 and 42 are formed to partially overlap the insulating coat 70 and the extended insulating coat 72. However, the thick-film busbars 40 and 42 do not need to overlap with either or both of the insulating coat 70 and the extended insulating coat 72. However, the sealing materials 80 and 82 need to be formed to overlap with the insulating coat 70 and the extended insulating coat 72. [Explanation of symbols]

[0039] 10 Heater Structure 20 Base material 30 Heater section 40, 42 Thick film busbars 401, 421 Main section 403, 423 First connection section 405, 425 connection part 50 Anisotropic conductive film 501, 503 Second connection section 60, 62 Thin film connection part 601, 621 Front end 603, 623 base 64,66 Thin-film busbars 641, 661 Main section 643, 663 extension 70 Insulating Coating 72 Extended Insulation Coating 80, 82 Sealing material 90 Flexible Printed Circuits (FPC)

Claims

1. A planar heater structure comprising a heater section, two thick busbars, an anisotropic conductive film, two thin film connecting sections, and an insulating coating, Each of the two thick film busbars has a main portion and a first connecting portion. The main portions of the two thick-film busbars are located apart from each other. The heater section is spread out in a planar shape and is connected between the main portions of the two thick film busbars. The anisotropic conductive film has two second connection portions, The two thin film connecting portions correspond to the first connecting portion of the thick film busbar, and also correspond to the two second connecting portions, Each of the two thin-film connecting portions connects the corresponding first connecting portion and the corresponding second connecting portion. The thick busbar is not in direct contact with the anisotropic conductive film. The thin film connection portion, except for the connection portion with the thick film busbar, is covered by the insulating coating and the anisotropic conductive film so as not to be exposed. Heater structure.

2. A heater structure according to claim 1, The heater structure further includes a sealing material that covers the thick film busbar so that the thick film busbar is not exposed. Heater structure.

3. A heater structure according to claim 1, The first connecting portion of the thick film busbar extends in the first horizontal direction, The thin film connecting portion protrudes from the first connecting portion in a second horizontal direction perpendicular to the first horizontal direction when viewed from above. Heater structure.

4. A heater structure according to claim 1, The heater structure further comprises two thin-film busbars, The thin film busbars are each located below the thick film busbars and connect the thick film busbars to the heater section. The thin film connection portion is formed integrally with the thin film busbar. Heater structure.

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