JPH03176972A - Terminal connection structure for flexible board - Google Patents

Abstract

PURPOSE:To surely connect terminal patterns, facilitate the connection work, and reduce the number of components by connecting the terminal patterns of two boards with a conducting adhesive, and fixing spacer layers of both boards by thermal deposition. CONSTITUTION:Circuit patterns 5a, 6a are printed on boards 1, 2, are terminal patterns 5, 6 are formed on their end sections. A hot melt type conducting adhesive 7 is coated only on the portions of the patterns 5, 6 by screen printing or the like. A vinyl chloride paint is printed on the boards 1, 2 to form spacer layers 3, 4. The boards 1, 2 are overlapped oppositely to the patterns 5, 6, and they are heated and pressed. The adhesive 7 is melted on the patterns 5, 6, and they are integrally stuck. Terminal patterns are securely connected, the connecting work is facilitated, and the number of components can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a terminal connection structure for flexible substrates that connects patterns on two substrates, at least one of which is made of a flexible substrate.

[Conventional technology]

2. Description of the Related Art Conventionally, flexible substrates in which a circuit pattern is formed on a flexible sheet have been put into practical use.

By the way, when connecting a circuit pattern formed on this type of flexible substrate to a circuit pattern formed on another flexible substrate or a rigid substrate, conventionally, a circuit pattern formed on an inner substrate is formed as a part of the circuit pattern. This was done by mechanically pressing the terminal patterns together.

FIG. 10 is a sectional side view of a main part showing a terminal connection structure of a conventional flexible board of this type.

As shown in the figure, in this conventional example, the upper case 8
A first flexible substrate 809 and a second flexible substrate 805 are placed between the spacer 801 and the lower case 803.
They are overlapped with 13 interposed therebetween. Then, the terminal pattern 811 provided on the first flexible substrate 809 and the second
Terminal pattern 807 provided on the flexible substrate 805 of
After the terminal pattern 811 is made to face each other via the six 815 provided on the spacer 813, the terminal pattern 811 is pressed against the terminal pattern 8 by a rubber pressing member 817 attached to the upper case 801.
07, thereby connecting the terminal patterns 807 and 811 at both ends.

[Problem to be solved by the invention]

However, in such a conventional terminal connection structure of a flexible board, since the connection between both terminal patterns 807 and 811 is mechanical, not only is the connection not reliable, but the resistance value of the connection part becomes large. There was also the problem that the connection work was time-consuming.

Further, in such a conventional terminal connection structure for a flexible board, a spacer 813 and a pressing member 817 are required, and there is also a problem that the number of parts increases.

The present invention has been made in view of the above-mentioned points, and provides a terminal connection structure for a flexible board with a simple structure, which ensures reliable connection between terminal patterns, facilitates the connection work, and reduces the number of parts. There is a particular thing.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a terminal connection structure for a flexible substrate with a first substrate 1 made of a flexible sheet and a second substrate 1 made of a flexible sheet or a hard plate.
A circuit pattern having terminal patterns 5 and 6 is formed on each of the inner substrates 1 and 2, and conductive adhesives 7 and 7 are applied on the terminal patterns 5 and 6, and the inner substrate 1. Apply thermoplastic resin to at least the portion surrounding the terminal patterns 5 and 6 of 2 to form the spacer M3,
4, the inner substrates are stacked so that both terminal patterns 5, 6 face each other, both spacer layers 3, 4 are brought into contact, and the contact surfaces are thermally welded, and the terminal patterns 5, 6 are
A conductive adhesive 7 is used to connect between the two.

Further, the present invention provides a terminal connection structure for a flexible board, which includes a first board 1 made of a flexible sheet, and a second board 9 made of a metal plate, on which an insulating layer 92 is formed by coating a thermoplastic resin on the top surface. A circuit pattern having terminal patterns 5 and 6 is formed on each of the inner substrates 1 and 9, and a conductive adhesive 7, is formed on at least one of the terminal patterns 5 and 6. 7 and apply the first
A spacer layer 3 is formed by coating at least a portion of the substrate 1 surrounding the terminal pattern 5 with a thermoplastic resin, and the inner substrates 1 and 2 are stacked so that both terminal patterns 5 and 6 face each other to form a spacer layer. 3 and the insulating layer 92 and thermally weld the contact surfaces, and the opposing terminal pattern 5
, 6 are connected with a conductive adhesive 7.

[Effect]

As mentioned above, the conductive adhesive 7,
7, and the spacer layer 3 of the first substrate and the spacer layer 4 (or insulating layer 92) of the second substrate are firmly fixed by thermal welding, so the connection between the terminal patterns of the flexible substrate is Become certain.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing the basic structure of the terminal connection structure of a flexible board according to the present invention, and FIG. 1(a) is a side sectional view;
FIG. 5B is a side cross-sectional view showing the terminal patterns 5 and 6 shown in FIG.

As shown in the figure, this flexible board terminal connection structure includes a first board 1 made of a flexible sheet and a second board 2 made of a flexible sheet. The spacer layers 3 and 4 formed around the terminal patterns 5 and 6, which form part of the circuit patterns 5a and 6a provided respectively, are thermally welded, and the terminal patterns on both substrates are further connected with a conductive adhesive 7. It is configured as follows.

Each component and the method for creating this terminal connection structure will be explained below.

FIG. 2 is a perspective view showing two boards 1 and 2 used in the terminal connection structure shown in FIG. 1, and FIG.
, 2 is a sectional side view showing a method of creating the terminal connection structure shown in FIG. 1 by connecting the terminal patterns of FIG.

As shown in FIGS. 2 and 3(a), the first substrate 1 and the second substrate 2 are flexible polyester films (in this embodiment, a film with a thickness of approximately 100-7 μm is used). It consists of a flexible substrate made of

As shown in FIG. 2, circuit patterns 5a and 6a are printed on the first substrate 1 and the second substrate 2 (silver carbon is used in this embodiment), and the edges thereof have small circular shapes. A terminal pattern 5°6 is formed.

Next, a hot melt type conductive adhesive 7.7 is applied only onto the terminal pattern 5 and terminal pattern 6 portions by, for example, screen printing (see FIG. 3(a)).

Next, as shown in FIGS. 2 and 3(a), the first substrate 1
and a vinyl chloride-based paint (in this example, 1 spacer resist XB-80 manufactured by Genji Kasei Co., Ltd.)
3") to form a spacer layer 3.4. However, the terminal patterns 5 and 6 of the first board 1 and the second board 2
No paint was applied to the portion where the was formed, and the portion was left as a circular exposed portion 31.41. Further, the thicknesses of the spacer layers 3 and 4 in this example were each about 50 μm.

8 Next, as shown in Fig. 2, the first board 1 and the second board 2 are overlapped and fixed so that the terminal patterns 5 and 6 of both are facing each other, but the fixing method is shown in Fig. 3. I will explain using

That is, first, as shown in FIG. 3(a), the second substrate 2 is placed on the support stand A, and then the first substrate 1 is placed on the second substrate 2.
Overlap. At this time, the terminal pattern 5 on the first substrate 1 and the terminal pattern 6 on the second substrate 2 face each other.

Next, a heated hot press B is pressed onto the first substrate 1 to form a spacer layer 3 printed on the first substrate 1 and a spacer layer 4 printed on the second substrate 2, as shown in FIG.
Press while heating. In this example, the hot press B was heated to 160°C and heated to 10k.
g/c+n'' for 4 seconds (in this example, the pressing pressure and heat applied to hot press B are:
10 to 20 kg/cm'' and 140 to 180° C.).

Here, the vinyl chloride paint that constitutes the spacer layers 3 and 4 has thermoplasticity, so if these are bonded together by heat, the contact surfaces of both the spacer layers 3 and 4 will be thermally welded and firmly fixed. . Note that the first substrate 1 and the second substrate in this embodiment
The adhesive strength of the substrate 2 (the force required to peel them off) is approximately 1
．． [It was 3 kg/cm.

Next, as shown in the same figure (C), after removing the hot press B, a heated hot press C having a small diameter is pressed from above the first substrate 1 in the area where the terminal pattern 5 is formed. heat up.

As a result, the conductive adhesives 7, 7 printed on the terminal patterns 5, 6, respectively, are melted and the two are bonded together.

As a result, the terminal pattern 5 and the terminal pattern 6 are connected as shown in FIG.

According to the above terminal connection structure, the first substrate 1 and the second substrate 2 are firmly fixed by the spacer layer 3.4, and the terminal patterns 5 and 6 are connected by the conductive adhesive 7.
The connection between the terminal patterns 5 and 6 is ensured.

Furthermore, if the smoothing surfaces H3, 4 are formed all around the terminal patterns 5, 6 as in this embodiment, the terminal patterns 5, 6
The space around the part (formed by the n-peak portions 31.degree. 41) is sealed from the outside. Therefore, this part will be waterproofed. Note that when the space around the terminal patterns 5 and 6 is sealed, if this area becomes hot, the air inside may expand and destroy this connection. In such a case, a groove for venting air may be provided in the spacer layer 3 or 4, and the groove may be used to establish electrical conduction with the outside air (a specific example is the groove 31d in FIG. 8(a)).

FIG. 4 is a diagram showing another embodiment of the terminal connection structure according to the present invention, in which FIG. 4(a) is a side sectional view and FIG. 4(b) is a plan view.

As shown in the figure, in this terminal connection structure, a notch 8 is formed around the portion of the first substrate 1 where the terminal pattern 5 is formed.

As shown in FIG. 1(b), when the first substrate 1 is pressed against the second substrate 2 by the press C, the terminals of the circuit pattern 5a printed on the first substrate 1 are The portion 5a-1 connected to the pattern 5 is slightly elongated.

This extended portion 5a-1 may be cut off. However, as shown in FIG.
If the notches 8 are provided in the substrate 1, the gap between the notches 8 will widen when the hot press C is pressed from above the first substrate 1, so there is no risk of the circuit pattern 5a being cut.

In the above embodiment, both the first substrate 1 and the second substrate 2 are made of flexible substrates, but the present invention is not limited to this, and the second substrate 2 is made of a hard insulating plate or a metal plate. It may also be constructed from a plate on which an insulating layer is formed.

FIG. 5 is a side sectional view showing still another embodiment of the terminal connection structure according to the present invention.

As shown in the figure, in this embodiment, a metal plate 91 and an insulator N92 are used in place of the second substrate 2 and spacer layer 4 shown in FIG.

That is, to create the terminal connection structure according to this embodiment, first, a first substrate 1 made of a flexible sheet and a thermoplastic resin were applied to the upper surface of a metal plate 91 to form an insulating layer 92. A circuit pattern having terminal patterns 5 and 6 is formed on each of the substrates 1 and 9.

Next, by the same method as shown in FIG.
, 9 are coated with hot melt type conductive adhesives 7, 7 on the terminal patterns 5, 6, and a spacer layer 3 surrounding the terminal patterns 5 of the first substrate 1 is formed of thermoplastic resin. The two substrates 1.9 are superimposed, and the contact surfaces of the spacer layer 3 of the first substrate 1 and the insulating layer 92 of the second substrate 9 are thermally welded,
Further, conductive adhesives 7, 7 on the terminal pattern 5.6
They were heat welded together.

If the insulating layer 92 provided on the metal plate 91 is made of thermoplastic resin in this manner, it is effective because the insulating layer 92 can have the same function as the spacer layer 4 shown in FIG. 1.

In each of the above embodiments, a vinyl chloride paint was used as the paint for the spacer layer 3゜4 or the absolute R layer 92, but the present invention is not limited thereto, and a thermoplastic resin paint may be used. Any kind of paint will do. However, in the above example, "Spacer Resist
This is because it is suitable for applying the present invention. The reason is explained below.

That is, a typical resist layer is made of an epoxy or polyester resin mixed with an inorganic filler (such as Si) and a solvent to improve printability. On the other hand, XB-803 is a PVC paste resin that does not contain inorganic fillers or solvents, and the cured coating film has flexibility. Furthermore, since it does not contain inorganic filler, it does not reduce the adhesive strength after thermocompression bonding.

Furthermore, since general adhesives (printing glue) have adhesive strength on the surface of the coating film after printing and hardening, it is necessary to apply a separator to this surface in advance.

On the other hand, XB-803 has no adhesive force on the surface of the cured coating film at room temperature, so there is no need to apply a separator to this surface in advance, and workability is good. Further, since common adhesives are sticky, they are not suitable for providing a specified thickness.

Next, although the flexible substrate used in each of the above embodiments is made of a flexible polyester film, the present invention is not limited to this, and any material may be used as long as it is a flexible sheet.

FIG. 6 is a diagram showing an embodiment in which an anisotropic hot-melt type conductive adhesive 7' is used as the conductive adhesive.

As shown in FIG. 2(b), in this embodiment, three terminal patterns 5-
1.5-2.5-3 and terminal pattern 6-1.6-2.6
-3, and apply conductive adhesive 7' over the entire terminal pattern 5-1.5-2.5-3, and apply the conductive adhesive 7' over the entire terminal pattern 6-1.6-2.6-3. Apply conductive adhesive 7'.

5 Next, a spacer layer 3 is printed on the first substrate 1 so as to surround the terminal patterns 5-1.5-2.5-3, and terminal patterns 6-1, 6-2, and 6-3 are printed. 2nd one surrounding
A spacer layer 4 is printed on the substrate 2. And Figure 3 (a
) and (b), the spacer layer 3 is thermally welded onto the spacer layer 4 by the same method.

Next, as shown in FIG. 3(c), the terminal pattern 5-1
．． 5-2. Hot press Cr heated from the top of 5-3
, Cz, Ca, and conductive adhesive 7 on both upper and lower sides.
′ is heat welded.

As a result, a terminal connection structure as shown in FIG. 3(a) is completed.

Here, this anisotropic hot melt type conductive adhesive 7' has a property of conducting only in the direction in which pressure is applied to the conductive adhesive 7'.

Therefore, between terminal pattern 5-1 and 6-1, terminal pattern 5
-2, 6-2, terminal patterns 5-3 and 6-3 are electrically connected.

The terminal 6 connection structure of the flexible substrate according to the present invention has been described in detail above, and next, an application example of an electronic component using this terminal connection structure will be described.

[Application example]

FIG. 7 is a diagram showing an example in which the present invention is applied to a terminal connection structure of a membrane switch. FIG. 7(a) is a plan view of the first substrate 1, and FIG. 7(b) is a plan view of the second substrate 2. It is.

Here, the first substrate 1 is constructed by screen-printing a desired circuit pattern 5a on a flexible substrate. A terminal pattern 5, a membrane switch contact pattern 5b, and an external lead-out terminal pattern 5c are provided in a predetermined portion of the circuit pattern 5a.

On the other hand, the second substrate 2 is constructed by screen-printing a desired circuit pattern 6a on a flexible substrate. A terminal pattern 6 and a contact pattern 6b of a membrane switch are provided in a predetermined portion of this circuit pattern 6a. Further, a six 6c is formed on the second substrate 2 to expose the external lead terminal pattern 5c to the outside.

Next, place the terminal patterns 5 and 6 on top of each other as shown in FIG.
Apply conductive adhesive 7 as shown in a).

Next, a spacer layer 3 is placed on these first substrate 1 and second substrate 2.
, 4 are printed, and the printing state is shown in FIG.

As shown in the figure, the spacer layers 3 and 4 are printed on almost the entire surface of the first substrate 1 and the second substrate 2, but the terminal pattern 5, the contact pattern 5b, the external lead-out terminal pattern 5c, and the terminal pattern 6 The area around the circuit pattern 6a is an exposed portion 31.
+ 3 l b + 31 cr r41.41b. In addition, the spacer layer 3 has each exposed portion 31, 31b, 31
A groove 31d without the spacer layer 3 is provided to connect between the grooves c. This groove 31d is provided in order to communicate with the outside air without sealing the space around the terminal patterns 5 and 6 and the contact patterns 5b and 6b (in the case of this embodiment, the groove 31d is connected to the exposed portion 31c). (The connected part will be open to the outside air).

Next, a second substrate 2 is placed on top of the first substrate 1.

At this time, the terminal patterns 5 and 6 face each other, and the contact patterns 5b and 6b face each other.

Then, as shown in FIG. 3(b), the spacer layer 3.4 is heat welded, and then, as shown in FIG. 3(c), the conductive adhesive 7 on the terminal patterns 5 and 6 is heat welded. For example, the terminal connection structure according to the present invention is completed. At this time, the contact patterns 5b and 6b become as shown in FIG. 9, and the spacer layers 3 and 4 serve as spacers to form a membrane switch.

Furthermore, the present invention may be applied to the external lead-out terminal pattern 5c formed on the first substrate 1, and this external lead-out terminal pattern 5c may be connected to a terminal pattern on another board.

Although the terminal connection structure of the flexible board according to the present invention has been described in detail above, the present invention is not limited to this.
Fold the flexible substrates, and separate the upper and lower substrates into the first substrate 1. It goes without saying that the second substrate 2 may also be used.

9 Furthermore, in each of the above embodiments and application examples, an example is shown in which a conductive adhesive is applied to both opposing terminal patterns provided on the first substrate and the second substrate, but the present invention is not limited to this. , this conductive adhesive may be applied only on one of the opposing terminal patterns.

Further, in each of the above embodiments and application examples, a hot melt type conductive adhesive was used as the conductive adhesive, but the present invention is not limited thereto, and other types of conductive adhesives may be used.

〔Effect of the invention〕

As described above in detail, the terminal connection structure for a flexible substrate according to the present invention has the following excellent effects.

(1) Since the terminal patterns can be securely fixed using conductive adhesive, and the spacer layer can be used between the two boards, not only is the connection between the terminal patterns reliable, but also the resistance value of the connection part is low, and the connection work is easy.

(2) Furthermore, conventional parts such as spacers and pressing members are no longer necessary, and the number of parts is reduced.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the basic structure of the terminal connection structure of a flexible board according to the present invention, Fig. 2 is a perspective view showing the board 1.2, and Fig. 3 is a diagram showing the connection between the terminal patterns of the boards 1 and 2. FIG. 1 is a side sectional view showing a method of creating the terminal connection structure shown in FIG. 1, FIGS. 4, 5, and 6 are views showing other embodiments of the terminal connection structure according to the present invention, and FIG. A diagram showing an example in which the present invention is applied to a terminal connection structure of a membrane switch, FIG. 8 is a diagram showing a state in which a spacer layer 3.4 is printed on the first substrate 1 and the second substrate 2, and FIG. FIG. 10, a diagram showing a membrane switch portion, is a side sectional view of a main part showing a terminal connection structure of a conventional flexible board. In the figure, 1... first substrate, 2, 9... second substrate, 3° 4... spacer layer, 5, 6... terminal pattern, 7,
7... Conductive adhesive, 5a, 6a... Circuit pattern, 92... Insulating layer. (a) Unexamined Japanese Patent Publication No. 3 176972 (7) (b) (a) 8 Unexamined Japanese Patent Publication No. 176972 (8) Fig. 4

Claims (2)

[Claims] (1) A first substrate made of a flexible sheet and a second substrate made of a flexible sheet or a hard plate, a circuit pattern having a terminal pattern is formed on each of the two substrates, and a circuit pattern is formed on each of the two substrates. Applying a conductive adhesive on at least one of the terminal patterns,
A spacer layer is formed by applying a thermoplastic resin to at least a portion surrounding the terminal pattern of both substrates, and the spacer layers of both substrates are brought into contact by overlapping the substrates so that the terminal patterns of both substrates face each other. A terminal connection structure for a flexible substrate, characterized in that the contact surfaces are thermally welded together, and the opposing terminal patterns of both substrates are connected using a conductive adhesive. (2) A first substrate made of a flexible sheet and a second substrate made of a metal plate whose upper surface is coated with thermoplastic resin to form an insulating layer, and each of the two substrates has a terminal pattern. A conductive adhesive is formed on at least one of the terminal patterns of both substrates, and a thermoplastic adhesive is applied to at least a portion of the first substrate surrounding the terminal pattern. A spacer layer is formed by applying a resin, and the two substrates are overlapped so that the terminal patterns of both substrates face each other, and the spacer layer of the first substrate and the insulating layer of the second substrate are brought into contact and the contact surfaces are thermally welded. In addition, a terminal connection structure for a flexible substrate, characterized in that opposing terminal patterns of both substrates are connected with a conductive adhesive.