JPH01124977A - Electrical connection structure - Google Patents

Abstract

PURPOSE:To simultaneously enable excellent anithotropic conductive and bonding characteristics by setting an arrangement for attaining a specified relative formula among the conductive circuit width, the space between conductive circuits, the sizes of conductors in anithotropic conductive films, and the spaces between conductors. CONSTITUTION:In connecting two wiring circuit boards 2 electrically, conductors 3b in anithotropic conductive films 3 are spaced vertically and laterally with a substantially fixed distance. It is structured such that formulae W>mA(m is 2-3) and D>nB (n is 1.5-2) are simultaneously attained, where A is the size of the conductor 3b, D the width of conductor circuit, W the space of conductive circuit. The two wiring circuit boards 2 satisfying the requirements and the conductive films are set together, heated, pressurized, and thus connected. It is thus possible to have a structure extremely superior in bonding characteristics important in the structure as well as in insulation characteristics between electrode, with extremely uniform connection resistance.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to an electrical connection structure using an anisotropic conductive film to connect seven fin pitch electrodes with an interelectrode pitch of 0.41 or less in a precision electronic circuit. In particular, it relates to the electrical connection structure described above.

(b) Prior Art Conventionally, the use of anisotropically conductive films of various structures is known for electrical connection of precision electronic circuits, particularly for electrical connection of fine pitch electrodes.

These anisotropically conductive films are disclosed in JP-A-59-9
As is known from Publication No. 3323, etc., conductors are randomly dispersed in an electrically insulating sheet, so-called conductor-dispersed type.
Also, in JP-A-57-141807, an anisotropic conductive film is produced by rolling an unvulcanized conductive rubber and an unvulcanized insulating rubber under heat, and then vulcanizing them under heat. Rubber sheets and vulcanized insulating rubber sheets are alternately laminated, pressure processed to form a block shape, and then this is cut in the lamination direction, and is a non-adhesive type.

(c) Problems to be Solved by the Invention However, when the conductor-dispersed anisotropic conductive film described in (1) above is used for mounting, it is necessary to increase the conductor's range width, and in addition, the insulation between the electrodes must be increased. The reality is that sex is extremely difficult to obtain.

In addition, since the conductor is formed in a linear shape, if the amount of the conductor is increased, the conductors will come into contact with each other and the insulation in the plane direction will be impaired, and conversely, if the amount of the conductor is decreased, the contact resistance will increase. In some cases, electrical continuity between the precision electronic device circuit terminal and the anisotropically conductive film is lost due to variations or mistouch problems.

When the non-adhesive anisotropic conductive film described in (1) above is used for mounting, it is necessary to use a holding jig in combination, resulting in an increase in cost.

In addition, because it is stretched under heat or vulcanized under heat, complicated and special equipment is required for its manufacture.

An object of the present invention is to provide an electrical connection structure that exhibits excellent anisotropic conductivity when a conventional anisotropically conductive film is used for mounting, and has good adhesiveness.

(d) Means for Solving the Problems As a result of extensive studies in order to solve the above problems, the inventor of the present invention discovered that using a specific anisotropic conductive film, The conductive circuit width at the connection part is
When the distance between conductive circuits is wSpl, the size of the conductor in the conductive film is A1, and the distance between the conductors is B, and a predetermined relational expression is established between them, excellent anisotropic conductivity and adhesion can be achieved at the same time. This discovery led to the completion of the present invention.

That is, in the electrical connection structure of the present invention, at least two printed circuit boards are connected by an anisotropically conductive film, and the anisotropically conductive film is an electrically insulating heat-sensitive adhesive film. It is composed of a conductor that penetrates this in the thickness direction, and the conductor has a size A and is separated at a substantially constant interval B in the vertical and horizontal directions. The conductive circuit width is D1, the interval between conductive circuits is W, W>mA (theory is 2-3), D>nB
(n is 1.5 to 2) holds true at the same time.

The present invention will be explained in detail below.

The printed circuit board to which the present invention is applied is not particularly limited as long as it has a conductive circuit on an insulating substrate, and typical examples include a 7-lexiple printed wiring board and a printed wiring board. Examples include a substrate.

Further, the anisotropically conductive film used in the electrical connection structure of the present invention is composed of an electrically insulating heat-sensitive adhesive film and a conductor that penetrates this in the thickness direction, and the conductor is There are no particular limitations as long as they are separated at substantially constant intervals in the vertical and horizontal directions.

Examples of the electrically insulating heat-sensitive adhesive film include films made of electrically insulating synthetic resin or rubber that exhibit adhesive properties when heated.

The above-mentioned synthetic resins include, for example, both thermoplastic resins and thermosetting resins, but thermoplastic resins are particularly preferred, and hot-melt resins, which have excellent thermal adhesion properties when heated and pressurized, are particularly preferred representative examples. It is mentioned as.

Examples of the above-mentioned hot melt) and IJf resins include polyolefin hot melt resins, polyamide hot melt resins, polyester, stellate hot melt resins, and ionomer resins.

In addition, the above-mentioned conductors include, but are not particularly limited to, metals such as zinc, tin, iron, nickel, cobalt, copper, lead, indium, silver, and gold, alloys containing these as main components, and lead. Examples include those formed of easily fusible alloys such as tin alloy, bismuth-tin-lead-indium alloy, bismuth-tin-lead-cadmium alloy, tin-lead-indium alloy, and bismuth-tin alloy.

Further, as the conductor, a mixture of a conductive material and a binder may be used.

As the conductive material, powder of the metal described above can be used, while as the binder, a thermoplastic resin or a thermosetting resin can be used.

The electrical connection structure of the present invention is characterized in that when the above-mentioned anisotropically conductive film is used to electrically connect the above-mentioned at least two printed circuit boards, the anisotropically conductive film is The conductors are separated vertically and horizontally at substantially constant intervals B, the size of the conductors is A, and the connection of the printed circuit board is 1 &
In the section, the width of the conductive circuit is calculated, and the interval between the conductive circuits is W, where W>mA (- is 2 to 3), D>nB (n is 1.
5 to 2) are configured so that they hold true at the same time.

The characteristics of an electrical connection structure that satisfies the above requirements and is made by laminating two printed circuit boards and an anisotropic conductive film and connecting this laminate by heating and pressurizing it are described in detail in Examples. As mentioned above, the variation in connection resistance value, which is important as an electrical property, is extremely small (it also has extremely high insulation performance between electrodes, and it also has extremely excellent adhesive properties, which is important as a structural material). There is.

Note that the method of stacking at least two printed circuit boards and anisotropically conductive films and connecting this laminate by heating and applying pressure does not require any special technology (it can be done using known methods). be.

(e) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

The electrical connection structure of the present invention (
1), for example, in a contact VC structure formed by connecting two printed circuit boards (2), (2) with an anisotropically conductive film (3) shown in FIG. (3) is composed of an electrically insulating heat-sensitive adhesive film (3a) and a conductor (3b) that penetrates this in the thickness direction, and the conductor (3b) has a size of (A), The wired circuit board (
2), at the connection part of (2), the conductive circuit (2a)
The width of the circuit is (D), the distance between the conductive circuits (2a) and (2a) is (W), and (W)>m(A) (m is 2 to 3),
The structure is such that (D)>n(B) (n is 1.5-2) holds true at the same time.

Examples 1 to 4 Width (
D), a wired circuit board (2) with a spacing (W) between conductive circuits (2a), (2a), in this case a 7 lexiple circuit board (
(manufactured by Nitto Electric Industry Co., Ltd., hereinafter referred to as FPC) for 2 sheets, solenoid rjl (2), (2), size (A) of conductor (3b), conductor (3b), (3b). Anisotropic conductive film with spacing (B) (manufactured by Nitto Electric Industry Co., Ltd., thickness 50 μm)
Plows (width 4sam, length 20-401) are piled up, heated,
The electrical connection structure (1) of the present invention having the structure shown in FIG. 1 was obtained by pressing together with a pressure press at a temperature of 180° C., a pressure of 6 kg/cm'', and a time of 30 seconds.

(In the electrical connection structure of the present invention obtained by
Measure the resistance between opposing conductive circuits of the PC using a gauge digital multimeter (manufactured by Takeda Riken) (5 measurements for each example)
00) L, on the other hand, the insulation resistance between adjacent conductive circuits of the FPC was measured using a terra ohmmeter (manufactured by Meguro Denpasha) (490 measurements for each example).

In addition, the adhesive strength was determined by fixing one FPC and pulling the other with a spring scale of 5 to measure the strength of the crack.

Those results are the second one! ! Shown in 2.

(Leaving space below) Table 1 Comparative Examples 1 to 6 Comparative Examples 1 to 3 used a conventional conductor array adhesive type anisotropic conductive film (having the structure explained in Conventional Example ■), and Comparative Examples 4 to 3 6 is a conventional conductor-dispersed anisotropic conductive film (
The structure explained in conventional example ■, Nitto Electric Industry Co., Ltd. S
Using the method, the width (D) of the conductive circuit (2a) shown in Table 1,
Conductive circuit (2a), width (W) between (2a), conductor (3b
) size (A), conductor (3b), interval (3b) (B
) connection structure was used as a sample.

Table 2 shows the measurement results of connection resistance, insulation resistance, and adhesive strength.

(Margin below) Table 2 Note 1) From Table 2, the connection resistance of the example is extremely low (and the variation 1 is also small, and the electric resistance in the plane direction is extremely low compared to the comparison example). It is recognized that it shows extremely high and excellent anisotropic conductivity, and also has extremely high adhesive strength.

(g) Effects of the invention The electrical connection structure of the present invention has the above configuration, and has extremely small variations in connection resistance value, which is important as an electrical characteristic.
Moreover, it has extremely high insulation performance between electrodes, and therefore exhibits excellent anisotropic conductivity and also has extremely excellent adhesive properties, which are important as structural materials.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of the present invention, Figure 2 is a sectional view of a connection structure in which an anisotropic conductive film is interposed between two printed circuit boards, and fIS3 is an anisotropic conductive film used therein. FIG. 2 is a perspective view of a conductive film. (1)... Electrical connection structure, (2)... Wired circuit board, (2a)... Conductive circuit, (3)... Anisotropic conductive film, (3a)... Heat sensitive Adhesive film, (3b
)...Conductor, (A)...Size of conductor, (B)...
・Space between conductors, (D)...width of conductive circuit, (W)・
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Claims (1)

[Claims] (1) In a connection structure in which at least two printed circuit boards are connected by an anisotropically conductive film, the anisotropically conductive film is an electrically insulating heat-sensitive adhesive film and a conductor that penetrates this in the thickness direction. The conductors have a size A and are separated by a substantially constant interval B in the vertical and horizontal directions, and the width of the conductive circuit is D at the connection part of the printed circuit board, and the distance between the conductive circuits is Let the interval of W be W>mA(m
2-3) and D>nB (n is 1.5-2).