Incremental printing of symbolic information – Thermal marking apparatus or processes – Specific resistance recording element type
Patent
1997-03-27
2000-09-19
Tran, Huan
Incremental printing of symbolic information
Thermal marking apparatus or processes
Specific resistance recording element type
40448, 174260, H05K 102
Patent
active
061219886
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to a printed wiring board on which electronic parts including LSIs and discrete components such as resistors and diodes are mounted and to a method of manufacturing the printed wiring board. The present invention also relates to electronic apparatuses, such as LCD devices or electronic printer devices, which employ such a printed wiring board.
DESCRIPTION OF RELATED ART
Electronic apparatuses, regardless of whether they are portable or stationary, are used in a diversity of fields including OA (office automation) and information-related fields. There is a growing demand today for a high-performance and multi-functional design as well as a small, light-weight and flat design, i.e., a compact design, for electronic apparatuses. For this reason, a miniature, light-weight and flat design is also desirable for circuit boards and printed wiring boards that constitute a part of the circuit boards, which are housed in the electronic apparatuses. High density packaging is also desirable and miniaturization of electrodes, terminals and trace patterns accommodates high density packaging.
For example, as shown in FIGS. 25 and 26, the specification of Japanese Patent Application No. Hei-5-223623 describes a prior art printed wiring board for use in a liquid crystal display device (LCD). A printed wiring board 1 is constructed of an elongated insulating board 2 on which a plurality of liquid crystal driving semiconductor chips (not shown) are mounted. The elongated insulating board 2 is provided, on a semiconductor chip mounting side surface 3, with input terminals 4, input side patterns 5 and output side patterns 6. Output terminals 7 of the printed wiring board 1 are formed on a bottom side 8 opposite to the semiconductor chip mounting side surface 3 as shown in FIG. 26 and are connected to the output side patterns 6 via through-holes 9. The output terminals 7 are connected to LCD input terminals (not shown) of a liquid crystal display panel (not shown), for example, via an anisotropic conductive film.
Along with high density packaging of the circuit board, high density and fine pitch design in the layout of the electrodes, terminals and pattern traces are promoted accordingly, and a higher density of through-holes and smaller diameters of the through-holes are thus implemented. Since the through-holes are typically formed by pressing or drilling, a reduction in the diameter of the through-holes is limited. Thus, advancement of fine pitch design of the through-holes and pattern traces is accordingly limited. Presently, the diameter of the through-holes is typically 0.1 millimeters (mm) at a minimum, and the pattern layout pitch, even if the through-holes are arranged in a staggered configuration, is typically 0.2 .mu.m at a minimum.
Fine pitch design of the through-holes may be improved even further if they are arranged in three rows, four rows or even more rows, but the board area required for forming the through-holes is expanded thereby resulting in the entire circuit board in becoming bulky. This fine pitch design conflicts with the more desirable miniature, light-weight and flat design. The smaller the diameter of the through-holes and the finer pitch of the through-holes are, the more difficult the drilling operation of the through-holes is. Also, the manufacturing cost of the printed wiring board is increased as a result of costs associated with broken drill bits and degraded production yield. Thus, the electronic apparatuses, such as liquid crystal display devices or electronic printer devices that have such a circuit board not only fail to meet the miniature, light-weight and flat design requirement but also results in a high manufacturing cost product.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a low-cost printed wiring board adapted for high density packaging and a manufacturing method therefor, wherein a miniature, light-weight and flat design is implemented while a fine-pitch design of electrodes, terminals and wirin
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patent: 3780430 (1973-12-01), Feeney
patent: 3971127 (1976-07-01), Giguere et al.
patent: 4335272 (1982-06-01), Pittenger
Seiko Epson Corporation
Tran Huan
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