JP3137212B2 - Flexible wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible wiring board used for mounting bare chip semiconductor elements and other circuit elements, and more particularly to an insulated flexible substrate having wiring formed on one side. The present invention relates to a flexible wiring board in which an opening is provided, and a lead for connecting a circuit element to be mounted in the opening to the wiring is protruded from an inner edge of the opening.

[0002]

2. Description of the Related Art As a system for mounting a bare chip semiconductor device using a flexible wiring board, a TAB (Tape) is known.
Automated Bonding) system and JP-A-2-3494 previously devised by the present inventors to improve high frequency characteristics.
No. 8 waveguide type film carrier system.

A conventional flexible wiring board will be described with reference to FIGS. First, FIG. 4 is a plan view showing a conventional flexible wiring board A used in a TAB system.
In this TAB system, a sprocket hole 2 for transport is opened on both sides in the longitudinal direction of an insulating flexible substrate 1 called a TAB tape, and a wiring pattern 3 is formed, thereby connecting a large number of flexible wiring boards A. It is provided in the state where it was done.

[0004] A bare chip semiconductor element (not shown) is thermocompression-bonded, thermal ultrasonic wave or the like to an internal lead 5 (part of the wiring pattern 3) provided to protrude from the central opening 4 of the flexible wiring board A. After that, the insulating flexible substrate 1 and the wiring pattern 3 are cut at the separation point 6, and the obtained flexible wiring board A is connected to a predetermined package or another wiring board by external leads 7 (wiring). (Part of pattern 3).

FIG. 5 is a partial sectional view showing a waveguide type film carrier B as another conventional flexible wiring board, and FIG. 6 is a sectional view taken along the line a--a in FIG. It is a figure showing a state. This waveguide type film carrier B is a flexible wiring board obtained by improving the above-mentioned TAB system so as to be suitable for use in a high frequency region, and has a wiring pattern 12 formed on one surface of an insulative flexible substrate 11 and an internal lead 13. Openings 14 and 15 for mounting a circuit element having (a part of the wiring pattern 12) are provided, and external leads 16 (a part of the wiring pattern 12) are provided. Reference numeral 18 denotes a waveguide,
The impedance is matched to the output impedance of the bare chip semiconductor element 17 (FIG. 6) and the characteristic impedance of the case or another wiring board.
The internal lead 13 and the external lead 16 have a structure in which the length is reduced.

This waveguide type film carrier B has a form in which a single-plate ceramic capacitor 19 having electrodes on the upper and lower surfaces is mounted for power supply bypass of the bare chip semiconductor element 17, and as shown in FIG. The element 17 and the single-plate ceramic capacitor 19 are mounted and arranged in the package 20.

At this time, the single-plate ceramic capacitor 19
Is thinner than the bare chip semiconductor element 17,
The thickness of the ground post 21 is adjusted by attaching it to the lower surface, and power is supplied to the bare chip semiconductor element 17 through the electrode terminal 22 on the upper surface of the single-plate ceramic capacitor 19. 23 is a bare chip semiconductor element 17
Reference numeral 24 denotes a connection bump.

FIG. 7 shows an example of a flexible wiring board C in which a circuit element for surface mounting is mounted. The structure of the flexible wiring board C is a print using a base material such as ordinary glass epoxy or paper bakelite. Similarly to the wiring board, a wiring pattern 32 is formed on an insulating flexible substrate 31, and a part mounting land 33 is formed on a part of the wiring pattern 32.
Is provided. The semiconductor element 34 and the surface mounting circuit element 35 are electrically and mechanically connected to the component mounting land 33 by a connection member 36 such as solder or a conductive adhesive. In the mounting form shown in the present example, a semiconductor element having a sealing structure such as a resin mold type is usually used as the semiconductor element 34.

[0009]

In the conventional mounting configuration example of the waveguide type film carrier B shown in FIGS. 5 and 6, the internal lead 13 is thermocompression-bonded or thermally ultrasonically applied to the bare chip semiconductor element 17 and the single-plate ceramic capacitor 19. Connected by bonding. However, the surface mounting circuit element 35 having electrode terminals 37 formed at both ends, which is generally used at present, as shown in FIG. 7, does not support the electrode terminals 37 for thermocompression bonding or thermosonic bonding. Therefore, at present, it cannot be mounted by thermocompression bonding or thermosonic bonding.

Therefore, in the waveguide type film carrier B having the above-mentioned conventional structure, it is possible to branch-connect a single-wave ceramic capacitor 19 having electrodes on the upper and lower surfaces and adapted to thermocompression bonding or thermosonic bonding to a circuit. However, it is not possible to mount a coupling capacitor or a damping resistor which must be inserted in series in the circuit.

Even if the electrode terminals 37 of the surface-mounting circuit element 35 are modified to be compatible with thermocompression bonding or thermosonic bonding, if the element shape is reduced to about 0.5 mm square, the bonding operation becomes extremely difficult. There is a problem that it becomes difficult.

That is, the bonding in the present mounting configuration is performed by holding the bare chip semiconductor element 17 and the single-plate ceramic capacitor 19 on a bonding stage (not shown) by means such as vacuum suction and fixing the internal leads 5 of the flexible wiring board to the electrode terminals. Since the positioning is performed at positions 11 and 21, when the surface-mounting circuit element 35 becomes small, it becomes extremely difficult to support and fix the element 35, and misalignment with the internal lead occurs during bonding.
A problem arises in that reliable bonding cannot be performed.

Therefore, this waveguide type film carrier B
In order to arrange a coupling capacitor, a damping resistor, and the like, a component mounting land 33 as in the conventional mounting configuration example shown in FIG. 7 is provided, and mounting is performed using a connection member 36 such as solder or a conductive adhesive. Conceivable.

However, even in this case, if the shape of the surface mounting circuit element 35 is reduced to about 0.5 mm square, the distance between the electrode terminals 37 of the element 35 becomes short, and the corresponding component mounting land is formed. 33 are set to 0.
It must be reduced to about 2 to 0.3 mm.
As a result, when the connection member 36 is supplied, the connection member 36 flows between the lower surface of the surface mounting circuit element 35 and the upper surface of the flexible wiring board, and a short circuit easily occurs between the component mounting lands 33. In particular, when a conductive adhesive is used as the connection member 36, there is a disadvantage that a short circuit can hardly be prevented.

Also, in the case of the flexible wiring board A of the TAB system shown in FIG. 4, the mounting configuration and procedure of bonding the internal leads 5 are the same as those of the waveguide type film carrier B. Attempts to mount circuit elements for surface mounting, such as coupling capacitors and damping resistors, which need to be connected in series to the circuit, have exactly the same problems as waveguide-type film carriers B.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a circuit element for surface mounting having electrode terminals formed at both ends, and having a smaller shape. Another object of the present invention is to provide a flexible wiring board that can be securely mounted without causing a short circuit between the electrode terminals.

[0017]

SUMMARY OF THE INVENTION To this end, the present invention provides an insulating flexible substrate having a wiring formed on one side thereof, wherein an opening is provided, and a circuit element to be mounted in the opening is provided at an inner edge of the opening. In a flexible wiring board formed by protruding a lead for connecting to the wiring, the shape and size of the opening are formed so that a circuit element to be mounted in the opening can be guided and inserted, and the lead can be inserted. Were opposing tongue-shaped leads having a width to length ratio of 1 or more.

Further, in the present invention, the circuit element is dropped into the opening from the side opposite to the one surface on the tongue lead, and an electrode terminal of the circuit element is connected to the tongue lead by a connecting member. be able to.

[0019]

In the flexible wiring board according to the present invention, the surface mounting circuit element having the electrode terminals at both ends is mounted and connected on the tongue-shaped leads opposed to each other in the opening, so that the short circuit is reliably prevented and the connection is made. Confirmation is also easy. At this time, since the inner wall of the opening functions as a guide for dropping the surface-mounting circuit element, mounting is easy and positional displacement can be prevented. Also, the width of the tongue-shaped lead is much wider than that of the conventional internal lead for bonding, and the connection of the circuit element to the electrode terminal is made at the edge of the tongue-shaped lead drawn out from the flexible wiring board. There is no deterioration of high frequency characteristics due to inductance.

[0020]

Embodiments of the present invention will be described below. FIG. 1 is a perspective view of a partial cross section of the flexible wiring board D of the first embodiment, and FIG. 2 is a cross sectional view taken along line bb of FIG. The same components as those shown in FIGS. 5 and 6 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the flexible wiring board D of this embodiment,
In order to connect the surface mounting circuit element 35, the opening 25
The tongue-shaped leads 26 are provided in place of the internal leads 13 so as to protrude into the openings 25 so as to be separated from each other and opposed to each other. The opening 25 is formed in a shape and size in which the surface-mounting circuit element 35 can be inserted, and the shape and size of the tongue-shaped lead 26 formed therein are as follows.
The ratio of the width to the length is 1 or more (that is, width>length);
The width is smaller than the width of the surface mounting circuit element 35.

The mounting procedure of the surface mounting circuit element 35 is as follows. One surface on which the wiring pattern 12 is formed is turned to the lower surface, and the connecting member 36 is supplied onto the surface of the tongue-shaped lead 26 from the opposite side (the upper surface). Then, using the inner wall of the opening 25 as a guide, the circuit element 35 is disposed so as to fall down,
The electrode terminal 37 is electrically and mechanically connected to the tongue-shaped lead 26.

At this time, since the opposing tongue-shaped leads 26 are completely isolated from each other, even if the surface-mounting circuit element 35 is mounted thereon, the conventional mounting structure provided with the component mounting lands 33 (FIG. As in the case of FIG. 7), the connection member 36 does not flow out to cause a short circuit failure, and the connection state of the surface mounting circuit element 35 can be checked and inspected from the surface on which the wiring pattern 12 is formed. Can be improved.

The surface mounting circuit element 35 is formed in the opening 2.
5 so that the side wall of the opening 25 serves as a guide, thereby facilitating mounting and preventing misalignment during mounting.

Further, in the conventional bonding method using the internal lead 13, the high-frequency characteristics may be deteriorated due to the influence of the lead inductance because the lead is thin.
The lead width of the tongue-shaped lead 26 of this embodiment is much wider than that of the conventional internal lead 13, and the surface-mounting circuit element 3
Since the connection of the lead 5 to the tongue-shaped lead 26 is made at the edge of the lead-out from the flexible wiring board D (when the lead-out), there is no deterioration in the high-frequency characteristics due to the influence of the lead inductance. This is the same even when a surface-mounting circuit element compatible with thermocompression bonding or thermosonic bonding is developed.

FIG. 3 is a partial plan view of the flexible wiring board E of the second embodiment. Although the width of the tongue-shaped lead 26 in the first embodiment is set to be equal to or smaller than the width of the surface-mounting circuit element 35, in this embodiment, the tongue-shaped lead 27 is set to be equal to or larger than the width of the surface-mounting circuit element 35. The leads 27 are formed so that both ends of the leads 27 reach the insulating flexible substrate 11.

In such a structure, since both ends in the width direction of the tongue-shaped lead 27 are supported and fixed, the mechanical strength is improved, and even if the surface-mounting circuit element 35 has a relatively large shape, Highly reliable mounting is possible. In addition,
The effects of checking the connection, preventing misalignment, and reducing the lead inductance are the same as those of the embodiment shown in FIGS.

[0028]

As described above, according to the flexible wiring board of the present invention, even when a surface-mounting circuit element having electrode terminals at both ends and having a small size and shape is mounted, a short circuit between the terminals due to the connection member is prevented. Not only can this be reliably prevented and the connection quality can be greatly improved, but also the inner wall of the opening functions as a guide for dropping the surface-mount circuit element, so that the circuit element can be easily mounted and displacement can be prevented, and the tongue can be prevented. There is no deterioration in high frequency characteristics due to the lead inductance of the lead.

Further, by applying the present invention to a flexible wiring board in which bare chip semiconductor elements are mounted by lead bonding, it becomes easy to arrange elements for series connection such as a coupling capacitor and a damping resistor, and to design a wiring. The degree of freedom is improved, and the function as a flexible wiring board module can be expanded.

[Brief description of the drawings]

FIG. 1 is a partial sectional perspective view of a flexible wiring board according to a first embodiment of the present invention.

2 is a cross-sectional view taken along the line bb of FIG. 1 in a state where a circuit element for surface mounting and a bare chip semiconductor element are mounted on the flexible wiring board of FIG. 1;

FIG. 3 is a partial plan view of a flexible wiring board according to a second embodiment of the present invention.

FIG. 4 is a plan view of a conventional flexible wiring board used in a TAB system.

FIG. 5 is a partial cross-sectional perspective view of a waveguide type film carrier as one type of a conventional flexible wiring board.

6 is a sectional view taken along line aa of FIG. 5 in a state where a bare chip semiconductor element and a single-plate ceramic capacitor are mounted on the waveguide type film carrier of FIG. 5;

FIG. 7 is a partial perspective view of a conventional flexible wiring board on which a surface mounting circuit element is mounted.

[Explanation of symbols]

A: Flexible wiring board used in TAB system,
1: Insulating flexible substrate called TAB tape,
2: sprocket hole 3: wiring pattern 4: opening
5: internal lead, 6: separation point, 7: external lead, B: waveguide type film carrier (flexible wiring board), 11: insulating flexible substrate, 12: wiring pattern, 13: internal lead, 14, 15: opening , 16: external lead, 17: bare chip semiconductor element, 18: waveguide, 19: single plate ceramic capacitor, 20: package, 21: earth post, 22: electrode terminal of single plate ceramic capacitor, 23: electrode of bare chip semiconductor element Terminal, 24: connection bump, C: flexible wiring board, 31: insulating flexible substrate made of glass epoxy or paper bakelite as a base material, 3
2: wiring pattern, 33: component mounting land, 34: semiconductor element, 35: surface mounting circuit element, 36: connecting member such as solder or conductive adhesive, 37: electrode terminal of surface mounting circuit element, D: The flexible wiring board according to the first embodiment of the present invention, 2
5: opening, 26: tongue-shaped lead, E: flexible wiring board of the second embodiment of the present invention, 2
7: Tongue-shaped lead.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 23/48 H01L 21/60

Claims (2)

(57) [Claims] An opening is provided in an insulating flexible substrate having a wiring formed on one side thereof, and a lead for connecting a circuit element to be mounted in the opening to the wiring is protruded from an inner edge of the opening. In the flexible wiring board formed by the above, the shape and size of the opening are formed so that a circuit element to be mounted in the opening can be guided and inserted, and the lead has a ratio of width to length of 1 or more. A flexible wiring board characterized by tongue-shaped leads opposed to each other. 2. The circuit device according to claim 1, wherein the circuit element is disposed on the tongue-shaped lead by being dropped into the opening from a side opposite to the one surface, and an electrode terminal of the circuit element is connected to the tongue-shaped lead by a connecting member. The flexible wiring board according to claim 1, wherein: