JPH05190609A - Tape carrier for tab - Google Patents

Abstract

PURPOSE:To reduce cross talk and make it possible to easily control the electric characteristics of a lead conductor by covering the vicinities of the lead conductor overlaying an insulating body with conductive members. CONSTITUTION:A lead conductor 1 is covered with an insulating body 2 and is surrounded by an upper ground plane 3 and a lower ground plane 4 while holding a predetermined capacitance between them, and the upper ground plane 3 and the lower ground plane 4 are connected to the grounding potential. Therefore, even there is external noise in the surrounding area, the noise cannot enter into the inside of a space surrounded by the upper ground plane 3 and the lower ground plane 4. Also, the electric field generated from the lead conductor 1 does not leaks outside of the upper ground plane 3 and the lower ground plane 4 thereby not affecting the outside, and there is no possibility of a signal from the lead conductor 1 becoming noise for other lead wires.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a TAB (Tape Automated B) which is one of mounting methods for semiconductor elements such as IC and LSI.
The present invention relates to a TAB tape carrier used in an onding method, and more particularly, to a TAB tape carrier capable of suppressing crosstalk and controlling the electrical characteristics of lead conductors.

As a conventional TAB tape carrier, for example, there is one shown in FIG. This TAB tape carrier is constructed by laminating a lead conductor 1 having a predetermined pattern on an insulator 2. The lead conductor 1 has a power supply lead and a ground lead in addition to a signal lead for signal transmission, and the power supply potential and the ground potential are supplied to the chip by using part of the lead conductor 1 as well.

On the other hand, recently, the speed of digital signals (speed of computer processing, speed of control equipment) has increased, and the clock frequency is from several tens of MHz to 100 MH.
It extends to the z stage. At such frequencies, it is necessary to control the electric constants such as the inductance and the capacitance of the leads to predetermined values so that the transmission signal is not distorted even for the leads that are simply transmission paths. That is, when bonded to a printed circuit board as a semiconductor device,
Impedance matching is performed by controlling the characteristic impedance of the lead conductor in order to prevent reflection of signals at the junction with the printed circuit board and the junction with the IC chip.

[0004]

However, the conventional TAB
Since the tape carrier for use is directly affected by noise from the adjacent lead conductors and other electronic components on the printed circuit board, the noise of the power supply lead or the ground lead is superimposed on the signal lead, or the signal of the signal lead is transmitted to other signals. Crosstalk occurs in which noise is superimposed on the leads as noise or noise of external electronic components is superimposed on the signal leads, which causes malfunction of the IC chip and other electronic components. In addition, it is relatively difficult to control the electrical characteristics of the lead conductor when performing impedance matching.

Therefore, an object of the present invention is to provide a TAB tape carrier which can reduce crosstalk and can easily control the electrical characteristics of the lead conductor.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a lead conductor coated with an insulator in order to reduce crosstalk and to easily control the electrical characteristics of the lead conductor. Provided is a TAB tape carrier surrounded by a conductive member.

The conductive member is made of, for example, a copper material, an iron-based alloy material, an aluminum material, or the like, and is arranged above and below the insulator. The upper conductive member is formed in an uneven shape so as to individually surround the lead conductors. Alternatively, the upper and lower conductive members may be electrically joined via the joining portion.

[0008]

In the TAB tape carrier of the present invention having the above structure, the conductive member is connected to a fixed potential such as ground even if there is external noise in the surroundings, so that the noise can be prevented from entering the lead conductor. it can. In addition, since the electric field generated from the lead conductor is grounded, it does not leak to the outside to affect external devices and the like, and the signal of one lead conductor does not become noise of another lead conductor. Further, by appropriately changing the thickness of the insulator, the capacitance of the lead conductor and the conductive member can be controlled, and the impedance of the lead conductor can be easily controlled. Further, when the upper and lower conductive members that sandwich the lead conductor are electrically joined, an electromagnetic shielding effect can be brought about.
Further, the inductance of the lead can be controlled by changing the degree of joining at the joining portion. In particular, when expecting an electrostatic shielding effect, use a conductive member such as copper or aluminum. When expecting an electromagnetic shielding effect, use a magnetic member such as iron. When expecting both shielding effects at the same time. ,copper,
Laminate materials such as aluminum and iron may be used.

[0009]

The tape carrier for TAB of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a TAB according to an embodiment of the present invention.
The cross-sectional structure of the tape carrier is shown. This TA
The tape carrier for B includes a lead conductor 1 having a predetermined pattern to be joined to an IC chip, an insulator 2 used for mounting a semiconductor element such as an IC and an LSI, and an upper ground arranged above and below the insulator 2. It is composed of a plane 3 and a lower ground plane 4.

The lead conductor 1 is covered with an insulator 2 and is surrounded by an upper ground plane 3 in an uneven shape so as to be shielded independently. That is, the lead conductor 1 is surrounded by the upper ground plane 3 and the lower ground plane 4 while having a predetermined capacitance. The upper ground plane 3 and the lower ground plane 4 are connected to the ground potential.

In the above TAB tape carrier, as shown in FIG. 2, since the upper ground plane 3 and the lower ground plane 4 are grounded even if there is external noise in the surroundings, noise is generated in the upper ground plane 3. In addition, the inside of the space surrounded by the lower ground plane 4 cannot enter. Further, since the electric field generated from the lead conductor 1 is grounded via the upper ground plane 3 and the lower ground plane 4, it leaks to the outside of the upper ground plane 3 and the lower ground plane 4 and affects the outside. Without lead conductor 1
Since the upper ground plane 3 is inserted between the two, there is no fear that the signal of the lead conductor 1 becomes noise of the other lead conductors 1. Further, by appropriately changing the thickness of the insulator 2, the capacitance between the lead conductor 1 and the ground planes 3 and 4 can be controlled, and the impedance of the lead conductor 1 can be easily controlled.

FIG. 3 shows a T according to the second embodiment of the present invention.
The cross-sectional structure of the AB tape carrier is shown. This TAB tape carrier has a structure in which an upper ground plane 3 and a lower ground plane 4 are electrically joined via a joining portion 5.

According to this TAB tape carrier, the shielding effect of the first embodiment can be further enhanced. That is, as shown in FIG. 4, when the magnetic flux due to the current flowing through the lead conductor 1 or the surrounding magnetic flux (noise) and the ground planes 3 and 4 interlink, the ground planes 3 and 4 correspond to the change in the interlinking magnetic flux. A counter electromotive force is generated in the current, and a current flows so as to cancel the interlinking magnetic flux change. Therefore, an electromagnetic shielding effect can be brought about, and if the electric connection between the upper ground plane 3 and the lower ground plane 4 is sufficient, the electromagnetic noise can be reduced by 20 to 50%. In addition, the inductance of the lead conductor 1 can be controlled by changing the degree of joining of the joining portion 5, and the impedance of the lead conductor 1 can be easily controlled together with the control of the electrostatic capacitance in the first embodiment. be able to.

Although the conductive member is a ground plane in the above embodiment, it may be replaced with a power plane.

[0017]

As described above, according to the TAB tape carrier of the present invention, since the periphery of the lead conductor covered with the insulator is surrounded by the conductive member, crosstalk can be suppressed and the lead conductor can be suppressed. It is possible to easily control the electric characteristics of the.

[Brief description of drawings]

FIG. 1 is a sectional view showing a TAB tape carrier according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the first embodiment.

FIG. 3 is a sectional view showing a TAB tape carrier according to a second embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the second embodiment.

FIG. 5 is a cross-sectional view showing a conventional TAB tape carrier.

[Explanation of symbols]

1 Lead conductor 2 Insulator 3 Upper ground plane 4 Lower ground plane 5 Junction

Claims (1)

[Claims] 1. A tape carrier for TAB comprising a film-shaped insulator (hereinafter referred to as an insulator) provided with a lead conductor having a predetermined pattern, wherein the lead conductor is surrounded by a conductive member and A tape carrier for TAB, which has a predetermined electrostatic capacity between the two.