JPH10200228A - Thin circuit board and contactless ic card using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the electric conductive bond between both surfaces of an insulation film, by providing a second connections at a part of a circuit pattern on one surface of the film corresponding to a first connections on the other surface of the film; the second connections being adhered to the first ones through a plurality of electrically conductive parts. SOLUTION: Coiled circuit patterns 3 and ICs 4 are formed and connected on both surfaces of a circuit board 5. Connections 1 are provided at a part of the pattern 3, one of them is disposed near the center of a coil and connected to the coil, and another is connected to the IC 4. On the connections 1 electric conductors 2 to be electrically bounded to the connections at the back surface are provided and laid like the 5 spots on a die, corresponding to the five electric conductors 2 per connection 1. The connections 1 and 2 are aligned and pressed and ultrasonic wave is applied. For the front-back connection, the heat and press bonding method may be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed circuit board having a double-sided connection, and more particularly to a flexible printed circuit board used for a non-contact type IC card.

[0002]

2. Description of the Related Art A flexible circuit board has a circuit pattern formed by attaching a metal foil such as copper to a substrate such as an insulating film, applying a resist for pattern formation, and performing processes such as etching and resist peeling. It can be obtained by FIG. 10 shows a flexible circuit board on which both-side bonding is not performed. One of the methods for electrically bonding to the other surface at the portion where the two-sided bonding on the circuit pattern is performed, that is, the connection portion is a through-hole processing method.

[0003] The through-hole processing method is a method of obtaining electrical continuity by first forming a hole in a connection portion and then coating the inner surface of the through hole and both ends of the opening with plating. FIG. 11 shows a state in which the perforation has been performed, and FIG. 12 shows a flexible printed circuit board on which double-side bonding has been completed after the through-hole processing step. Since most of the inner surface of the through hole 6 in FIG. 11 is an insulating film constituting the insulating film circuit board 5, the through hole 6 is in an electrically insulated state. Bonding.
FIG. 12 shows the through hole 6 in this state.

An advantage of the through-hole processing method is that a reliable electrical conduction can be obtained because a hole is formed and the through-hole is plated. However, the through-hole processing method has a problem that the number of steps is large and the manufacturing cost is high due to its complexity.

[0005] In addition to through-hole processing, known methods for performing double-sided bonding include a heat-press bonding method and an ultrasonic wave application method. Heat and pressure bonding method is to deform the metal foil forming the connection part by pressing the connection part formed on the circuit pattern, and simultaneously evaporate the insulating film sandwiched between the metal foils while heating It is a double-sided bonding method that obtains electrical continuity by bringing metal foils into close contact,
The ultrasonic wave application method is a method in which the metal foil is deformed by pressurizing a connection portion, and at the same time, an ultrasonic wave is applied to evaporate the insulating film so that the metal foils are brought into close contact with each other to obtain electrical continuity. What is common to the two bonding methods, the heat-press bonding method and the ultrasonic application method, is that the processing is simpler than the through-hole processing method, the number of steps is small, and the cost is low. However, there is a problem that it is difficult to obtain reliable electrical continuity as compared with the through-hole processing method.

For example, FIG. 9 is a plan view showing the inside of a non-contact type IC card using a flexible circuit board bonded to both sides by an ultrasonic wave application method or a heat-pressure bonding method. Reference numeral 1 denotes a connection portion provided on a part of the circuit pattern 3 formed in a coil shape and having an electric conduction portion 2;
Denotes an IC, and 5 denotes a substrate using an insulating film. Two connecting parts 1 are provided near the center of the coil and one near the IC, and each connecting part 1 is provided with one electric conduction part 2.

However, while the ultrasonic application method or the heat and pressure bonding method is easy to process, the quality varies from the electrically conductive surface. For example, FIGS. 2, 13, and 14 are side views of the connection unit 1, the electrical conduction unit 2, and the circuit board 5. FIG. 2 shows a preferred state of double-sided bonding, and FIGS.
Indicates an undesirable state of double-sided bonding. The preferred double-sided bonding is that, as shown in FIG. 2, the metal foil forming the connection portion 1 which is a part of the circuit is completely in close contact with the metal foil forming the connection portion 1 on the other surface, and the circuit board 5 Is a state in which the insulating film forming is completely evaporated in the electric conduction portion 2.

An undesirable double-sided bonding will be described with reference to FIGS. FIG. 13 shows a state where the insulating film forming the circuit board 5 is not evaporated and remains between the metal foils forming the connecting portion 1 due to insufficient heating energy. In this case, the circuit is in a disconnected state or a state in which electric conduction is very unstable.
On the other hand, FIG. 14 shows a state in which not only the insulating film forming the circuit board 5 but also the metal foil evaporates due to excessive heating energy, and the through-hole 6 is opened in the connection portion 1. In this case, if the metal foils around the through hole 6 are in close contact with each other, electrical conduction is ensured therethrough, so that a complete disconnection state does not occur. If the insulating film has not completely evaporated, the circuit will be in a disconnected state. In this case, electrical conduction can be obtained by supplying the Ag paste or the solder 7 to the through holes 6 as shown in FIG. The advantage of the ultrasonic application method is lost.

[0009]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and can easily perform double-sided bonding by using a heating and pressing bonding method and an ultrasonic wave application method, and is a flexible material having excellent electrical conductivity. It is an object to provide a circuit board.

[0010]

According to a first aspect of the present invention, there is provided a thin circuit board comprising: an insulating film; a circuit pattern provided on one surface of the insulating film; a connecting portion provided on a part of the circuit pattern; A second connection portion provided on the other surface of the insulating film corresponding to the first connection portion and closely attached to the first connection portion by applying heat and pressure, or applying ultrasonic waves while applying pressure. And the first connection portion and the second connection portion are connected to each other by a plurality of electric conduction portions.

According to a second aspect of the present invention, there is provided a thin circuit board, comprising: an insulating film; circuit patterns provided on both sides of the insulating film; It is provided with a connecting portion having a plurality of electric conducting portions which are brought into close contact by applying pressure or applying ultrasonic waves while applying pressure.

According to a third aspect of the present invention, the thin circuit board according to the first or second aspect has a thickness of 50 μm.
The following insulating film was used.

According to a fourth aspect of the present invention, there is provided the thin circuit board according to any one of the first to third aspects, wherein the connecting portion has one point near the center of the connecting portion and four points around the connecting portion, for a total of five points. It is provided with an electric conduction part.

According to a fifth aspect of the present invention, there is provided a thin circuit board according to the first to fourth aspects, wherein the electrically conductive portion has a diameter twice or more the thickness of the insulating film.

According to a sixth aspect of the present invention, there is provided a non-contact type IC card according to the first to fifth aspects, wherein a thin circuit board having a circuit pattern formed in a coil shape is used.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a plan view showing the inside of a non-contact type IC card using a thin circuit board according to Embodiment 1 of the present invention, and FIG. 2 is a side view showing the configuration of a connection portion and an electrical conduction portion in FIG. FIGS. 3 to 6 show the arrangement of five electrical conducting parts provided at the connecting part in FIG.
It is explanatory drawing which shows the order which performs double-sided joining about each electrical conduction part.

In FIG. 1, 5 is a circuit board made of polyimide or the like, and 3 is a coil-shaped circuit pattern provided on both sides of the circuit board 5. Reference numeral 4 denotes an IC connected to the coil-shaped circuit pattern 3, and reference numeral 1 denotes a connection portion provided on a part of the circuit pattern 3, and two connection portions 1 are provided in FIG. . One of them is located near the center of the coil and connected to the coil,
The other is connected to IC4. Reference numeral 2 denotes an electrical conduction portion provided on the connection portion 1 and electrically connected to the connection portion on the back surface when viewed from FIG. Five electrical conduction parts 2 are arranged for each connection part 1, just like the “5” eyes of a dice.

FIG. 2 is a side view showing a state in which one of the five electrical conduction parts 2 provided on the connection part 1 is joined to both sides. In FIG. 2, t is a code indicating the thickness of the insulating film substrate, and 1 is a code indicating the diameter of the electrical conduction portion. In the present invention, the circuit board 5 has a thickness t of 50 μm or less.
When t becomes 50 μm or more in thickness, more energy needs to be added to evaporate the circuit board 5, and more delicate energy control is required.

That is, if the output energy is excessive, the connection portion 1 formed of metal foil may be damaged by the energy, and if the output energy is insufficient, the circuit board 5 is formed. The insulating film remains between the connecting portions 1 on both sides, and electrical conduction cannot be obtained.
Further, as t becomes thicker, a force for pressing the connection portion 1 is required, and the connection portion 1 may be damaged. Therefore, in the present invention, a substrate having a thickness of 50 μm or less is employed.

Further, in the present invention, the electric conduction portion 2
Has a diameter l which is at least twice the thickness t. When the diameter l of the electric conduction portion 2 is reduced with respect to the thickness t, a joining process such as a heating / pressing portion or an ultrasonic wave application portion of the double-side joining device 8 shown in FIG. The part 9 has a sharp shape. That is, the pressing force for pressing the metal foil forming the connecting portion 1 or the heat or ultrasonic energy for evaporating the insulating film forming the circuit board 5 is concentrated on one minimum point, and the energy is very easily connected. The part 1 can be damaged.

FIGS. 3 to 6 are explanatory views for explaining the processing steps of the five electric conducting parts 2 provided on the connecting part 1. FIG. In other words, this indicates that the electric conducting portions 2 are joined on the connecting portion 1 on both sides in the numerical order shown in the circle of the electric conducting portion 2. FIGS. 7 and 8 show a double-side bonding apparatus 8 for performing double-side bonding according to the present invention, in particular, a connection processing section 9 thereof.
It shows. FIG. 7 is a side view of the joining section 9 of the double-side joining apparatus 8 as viewed from the side, and FIG. 8 is a front view of the joining section 9.

In order to provide the electrical conduction portion 2 in the connection portion 1, as shown in FIGS. 3 and 4, a method of performing double-sided bonding for each of the five electrical conduction portions 2 and FIGS. As shown in the figure, there is a method of performing double-sided bonding on five electrical conductive portions 2 at a time. When performing double-sided bonding at a time, a bonding section 9 of a double-sided bonding apparatus 8 as shown in FIGS. 7 and 8 is used.

As shown in FIGS. 3 and 4, the joining portion of the double-side joining device used when machining the electric conducting portions 2 one by one has a pen-shape shape (not shown). ). Ultrasonic waves are applied while applying pressure in accordance with the position on the connection portion 1 where the electric conduction portion 2 is provided, that is, 1 in the circle of the electric conduction portion 2 shown in FIG. 3 or FIG. In addition, as a method of performing double-sided bonding, a heat-pressure bonding method may be used in addition to the ultrasonic wave application method. Thereafter, similarly, according to the numbers in the circles of the electric conducting portions 2 in FIG. 3 or FIG.

The order shown in FIGS. 3 and 4 is a reference example.
Basically, it does not matter if the two-sided bonding is performed in any order. However, a feature of the present embodiment is that the double-sided joining of the central electric conduction portion 2 is performed last. That is, first, the both sides of the peripheral electric conduction portion 2 are joined, and finally, the both sides of the central electric conduction portion 2 are joined. It has been confirmed that the four corners are fixed by performing double-sided bonding of the surrounding electric conduction portion 2, and that fixing the four corners has an effect that the double-sided bonding at the center is more reliably performed.

FIGS. 5 and 6 show the order in which five electric conducting parts 2 are provided on the connecting part 1 at a time. FIG.
As shown in the figure, the bonding section of the double-side bonding apparatus used when performing the double-side bonding of the five electrical conducting sections 2 at a time is provided with five pen shaft-shaped bonding sections, and Ultrasonic waves are applied to the position where the electric conduction section 2 is processed. A heat and pressure bonding method may be used. In FIG.
All the numbers in the circle indicating “1” indicate that the five electrically conductive portions are simultaneously bonded on both sides. Therefore, all the pen shaft-shaped joint processing portions of the double-sided joint processing device have the same length (the double-sided joint processing device and the joint processed portion used in this method are not shown).

As shown in FIG. 5, an advantage of simultaneously joining the five electrically conductive portions 2 to both sides is that the structure of the device can be simplified. In the case where the electric conduction portions 2 are bonded on both sides one by one, a mechanism for positioning the pen shaft-shaped joint processing portion on the electric conduction portion 2 for performing double-side joining is required. Once the five are integrated, the above mechanism is not required. In addition, since the electrical conduction portion can always be arranged at a predetermined position, accurate and fine processing can be realized.

FIG. 6 also employs a method in which five electric conduction portions 2 are simultaneously bonded on both sides. What is different from FIG. 5 is that a bonding section 9 of a double-side bonding apparatus 8 as shown in FIG. 7 is used. That is, the joint processing section 9 of the double-sided bonding apparatus 8 shown in FIG. 7 has a stroke of the central joint processing section 9 which is slightly shorter than the other of the five integrated pen-shape joint processing sections 9. The joining sections 9 at the four corners with a long stroke of the joining apparatus 8 first come into contact with the connecting section 1 and start joining. Next, the center joining portion 9 having a short stroke comes into contact with the connecting portion 1 to perform joining.

As described above, by making the strokes of the four joint processing parts 9 longer than those at the center, the electric conduction parts 2 at the four corners can be fixed first, and the electric conduction parts at the center in a stable state. 2 can be performed. In other words, by fixing the four corners first, it is possible to prevent problems such as distortion of the surface of the connection portion 1, a minute gap between the circuit board 5 and the connection portion 1, and a shift between the circuit board 5 and the connection portion 1. The central electric conduction part 2 can obtain more reliable electric conduction.

When the quality inspection was performed on the thin circuit board shown in FIG. 1 and the thin circuit board shown in FIG. 9, a remarkable improvement in the rejection rate was found by using a plurality of electrically conductive portions of the connection portion. The quality inspection is performed on any 2 on the circuit pattern 3.
This is performed by measuring the resistance between points, for example, A and B in FIGS. 1 and 9, and if the resistance value is higher than a predetermined value, the substrate is determined to be defective.

When the thickness of the substrate 5 is 50 μm and the connection portion 1 is provided with one electrical conduction portion 2, the failure rate is about 50%, and when five electrical conduction portions 2 are provided, it is close to 0%. Value.
This is because, as a result of the provision of the plurality of electric conducting parts 2, even if some of the five electric conducting parts 2 are partially incompletely joined on both sides, the remaining electric conducting parts 2 are completely joined on both sides. Means that stable electrical conduction is ensured. Electrically conductive part 2 in which both sides are completely joined
It is also confirmed that even if the four electrical conductive portions 2 are incompletely bonded on both sides, there is no problem in the function of the circuit in the quality inspection.

[0031]

As described above, the connection portion 1 of the circuit pattern 3 formed on one surface of the insulating film forming the circuit board 5
And, by heating the metal foil constituting the connection part provided at a position corresponding to the connection part on the other surface of the circuit board, the metal foil is pressed while evaporating the insulating film, and the metal foils are separated from each other. The two-sided bonding is performed electrically by bringing them into close contact. A plurality of electrically conducting parts 2 for each connection part 1
Is provided, reliable electrical conduction can be obtained, and the defective rate can be reduced.

Further, by using a circuit board 5 having a thickness of 50 μm or less, both-side joining can be performed easily and reliably.

Further, by providing five electrical conduction portions 2 at each connection portion 1 and arranging one electrical conduction portion 2 near the center of the connection portion 1 and four electrical conduction portions 2 around the center, reliable double-sided bonding can be achieved. In particular, reliable electrical continuity can be obtained in the central electrical continuity portion 2.

Further, by setting the diameter l of the electric conduction portion 2 to be at least twice the thickness t of the circuit board 5, stable processing can be performed without damaging the metal foil.

In addition, by using a thin circuit board in which the circuit pattern 3 is formed in a coil shape and provided with a connection portion having a plurality of electric conduction portions for a non-contact type IC card, double-sided bonding is easy and reliability is improved. It has become possible to provide a non-contact type IC card with high reliability at low cost.

[Brief description of the drawings]

FIG. 1 shows a non-contact type I according to Embodiment 1 of the present invention.
It is a top view which shows the inside of a C card.

FIG. 2 is a side view showing a connection portion and an electric conduction portion of the non-contact type IC card in FIG.

FIG. 3 is an explanatory view showing the order in which electric conduction portions on a connection portion are joined on both sides.

FIG. 4 is an explanatory diagram showing the order in which electric conduction portions on a connection portion are joined on both sides.

FIG. 5 is an explanatory view showing the order in which electric conduction portions on a connection portion are joined on both sides.

FIG. 6 is an explanatory diagram showing the order in which electric conduction portions on a connection portion are joined on both sides.

FIG. 7 is a side view showing a joint processing portion of the double-sided connection processing device.

FIG. 8 is a front view showing a joint processing portion of the double-sided connection processing device.

FIG. 9 is a plan view showing the inside of a conventional non-contact type IC card.

FIG. 10 is a side view of a thin circuit board showing a state before through-hole processing is performed.

FIG. 11 is a side view of the thin circuit board showing a state after the board has been punched.

FIG. 12 is a side view of the thin circuit board showing a state where solder or a conductive paste is applied.

FIG. 13 is a side view showing a state of a bonding portion and an electric conduction portion of the thin circuit board having incomplete double-sided bonding.

FIG. 14 is a side view showing a thin circuit board having an electric conduction portion having a through hole.

FIG. 15 is a side view showing a thin circuit board in which an Ag paste or a solder is applied to an electric conduction portion having a through hole.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Connection part 2 Electrical conduction part 3 Circuit pattern
Reference Signs List 4 IC 5 Circuit board 6 Through hole 7 Solder 8 Double-sided bonding processing device 9 Bonding processing part t Substrate thickness l Electrical conduction part diameter A, B Arbitrary position to measure resistance

Claims (6)

[Claims] 1. An insulating film, a circuit pattern provided on one surface of the insulating film, a connecting portion provided on a part of the circuit pattern, and a second surface of the insulating film corresponding to the first connecting portion. Provided is provided with a second connecting portion joined to the first connecting portion by applying ultrasonic waves while heating and pressurizing, or pressurizing, wherein the first connecting portion and the second connecting portion are plural Characterized by being connected to each other by an electrically conductive portion of the thin circuit board. 2. An insulating film, circuit patterns provided on both sides of the insulating film, and heat-pressing,
A thin circuit board comprising: a connecting portion having a plurality of electrically conductive portions joined by applying ultrasonic waves while applying pressure. 3. The thin circuit board according to claim 1, wherein the insulating film has a thickness of 50 μm or less. 4. A connection part is located near the center of the connection part.
The thin circuit board according to any one of claims 1 to 3, further comprising a total of five points of electrical conduction, and four points around the point. 5. The electric conduction portion has a thickness of 2 mm of the insulating film.
The thin circuit board according to any one of claims 1 to 4, wherein the circuit board has a diameter twice or more. 6. A non-contact IC card using the thin circuit board according to claim 1, wherein the circuit pattern is formed in a coil shape.