Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1999-10-08
2001-09-11
Gaffin, Jeffrey (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S255000, C174S256000, C174S258000, C174S259000, C361S749000, C361S750000
Reexamination Certificate
active
06288343
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printed circuit board, and more particularly to a printed circuit board of a multi-layered structure in which each of the multi-layers has the same heat expansion coefficient and a middle layer of the multi-layers is exposed outside to form an electrical interconnection portion. In specific, the present invention relates to a printed circuit board in which a source PCB and a connector PCB have a multi-layered structure and the connector PCB that connects the source PCB with the control PCB is integrated with the source PCB.
2. Description of the Related Art
Generally, printed circuit boards (PCBs) on which electrical interconnections are printed and various devices are mounted are being used in most of electronic appliances.
Like other electronic apparatus, a liquid crystal display (LCD) also uses such PCBs for mounting the driving units displaying images on the LCD panel.
Generally, an LCD includes an LCD panel including a TFT substrate and a color filter substrate, a light source, and driving units which include a gate PCB, a source PCB, and a control PCB.
Gate PCB is used for driving gates of a plurality of thin film transistors formed on TFT substrate and source PCB is used for driving sources of the plurality of thin film transistors.
Generally, a control PCB is provided in addition to the gate PCP and the source PCB.
In LCDs that a gate PCB, a source PCB, and a control PCB are separate from each other, a connecting member such as flexible printed circuit (FPC) electrically connects the gate PCB, the source PCB and the control PCB.
When an FPC connects the source PCB and the control PCB, both terminals of the FPC are respectively connected to ports respectively mounted on the edges of the source PCB and gate PCB by a tape automated bonding (TAB) tape or by soldering. A TAB tape or soldering requires bonding, which lowers the productivity in general.
To resolve the above-described drawback, a source PCB integrated with a connector PCB is provided. The source PCB and the connector PCB respectively have a multi-layered structure.
A multi-layered structure PCB includes a flexible middle layer, a pair of rigid layers disposed on both surfaces of the flexible middle layer, and at least one conductive pattern layer disposed between the flexible middle layer and the rigid layer.
To connect the source PCB and the connector PCB, a flexible FPC is used and connected to a conductive pattern layer of each of the source PCB and the connector PCB. Here, both connectors of FPC extend not to the whole surface of the conductive pattern layer of the two PCBs but to edge portions of the PCBs facing each other, creating a step at the connection of FPC due to the thickness of the FPC. Such a step weakens the adhesive force between the conductive pattern layer and the overlying rigid layer.
Also, since the flexible middle layer of polyimide has a heat expansion coefficient different from the rigid layer of FR4 placed on both surfaces of the middle layer, the rigid layer and the flexible layer are delaminated during the soldering process of high temperature, lowering the reliability of the product.
In addition, polyimide that is more expensive than FR4 increases the total production cost of PCB.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to prevent delamination generation between layers of source PCB and connector PCB.
It is another object to enhance the productivity and reliability of PCB having multi-layered structure.
It is still another object to provide PCBs having a low fabrication cost.
To achieve the above objects and other advantages, the present invention provides a printed circuit board comprising a first layer having a first stacked region, a second stacked region spaced apart from the first stacked region by a selected distance, and a flexible connection part disposed between the first and second stacked regions, and extending to the first stacked region and the second stacked region with selected width and length, the flexible connection part having a conductive pattern layer for signal transmission between the first stacked region and the second stacked region and a protective layer for protecting the conductive pattern layer; a pair of second layers disposed apart on an upper surface of each of the first and second stacked regions of the first layer and having a first signal pattern layer on both surfaces of each of the second layers, wherein said first signal pattern layer of the second layer is electrically connected to the conductive pattern of the flexible connection part; a pair of upper metal layers disposed on respective upper surfaces of the second layer, the upper metal layer interposing a first insulating adhesive between the upper metal layer and the second layer; a pair of third layers disposed apart on a lower surface of each of the first and second stacked regions of the first layer and having a second signal pattern layer on both surfaces of each of the third layers; and a pair of lower metal layers disposed on respective lower surfaces of the third layers, the lower metal layer interposing a second insulating adhesive between the lower metal layer and the third layer.
It is desirable that the first, second, and third layers are made of the same FR4 containing glass epoxy resin.
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Ahn Jung-Hyun
Lee Jong-Hyun
Gaffin Jeffrey
Howrey Simon Arnold & White , LLP
Patel I B
Samsung Electronics Co,. Ltd.
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