Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2000-06-29
2004-06-22
Von Buhr, Maria N. (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C347S040000, C228S043000
Reexamination Certificate
active
06754551
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to printed circuit board manufacturing and in particular to an apparatus and method for depositing various patterns on printed circuit boards using jet-dispensing technology.
REFERENCES
There follows a list of references that is referenced in the following description.
1. Sematech Dictionary (http://www.sematech.org/public/publications/dict/con_to_cz.htm)
2. Circuit Board Terminology (http://www.sdcbs.com/term.htm)
3. Institute for Interconnecting and Packaging Electronic Circuits (IPC), Lincolnwood, Ill.
4. SMEMA 7 Fluid Dispensing Terms and Definitions (http://ipc.org/html/smemastandards.htm)
5. SMEMA 3.1 Fiducial Mark Standard (http://ipc.org/html/smemastandards.htm)
6. Printed circuits handbook, /Clyde F. Coombs, Jr., editor-in-chief—3
rd
ed. ISBN 0-07-012609-7
7. U.S. Pat. No. 5,637,426 Uchikawa June 1997
8. U.S. Pat. No. 4,668,533 Miller May 1987
9. Laid-Open (Kokai) No. Hei 9-18115, Niijima January 1997, Japan
10. U.S. Pat. No. 4,767,489 Lindner August 1988
11. U.S. Pat. No. 5,270,368 Lent et al, December 1993
12. Laid-Open (Kokai) No. Hei 11-87883, Takada et al., March 1999, Japan
13. U.S. Pat. No. 4,748,453 Lin et al., May 1988
14. U.S. Pat. No. 4,963,882 Hickman, October 1990
15. U.S. Pat. No. 4,999,646, Trask, March 1991
16. U.S. Pat. No. 5,239,312, Mema et al., August 1993
17. U.S. Pat. No. 5,790,150 Lidke et al., August 1998
18. U.S. Pat. No. 5,587,730, Karz, December 1996
19. U.S. Pat. No. 5,984,455, Anderson, November 1999
20. U.S. Pat. No. 6,030,072, Silverbrook, February 2000
GLOSSARY
There follows a glossary of terms used in the following description. The definitions of the terms are given for convenience of explanation and should not be regarded as binding.
SMT
Surface Mount Technology
SMA
Surface Mount Adhesive
HASL
Hot Air Solder Leveling
PCB
Printed Circuit Board
Conformal Coating
thin, nonconductive film applied to a circuit for
environmental or mechanical protection; usually
plastic or inorganic [1]
UV curing
Polymerizing, hardening, or cross linking a low
molecular weight resinous material in a wet coating
or ink, using UV (ultraviolet) light as an energy
source [2]
Etching
The process of removing unwanted metallic
substance (bonded to a base) via chemical, or
chemical and electrolytic means [2]
Resist
Coating material used to mask or to protect selected
areas of a printed wiring board (PWB) from the
action of an etchant, solder, or plating [2].
Also conform IPC-T-50 b specification [3]
Jet Dispensing
A non-contact dispensing process that utilizes a
fluid jet to form and shoot droplets of adhesive,
solder, flux or other fluids from the jet nozzle to
the substrate [4]
Drop-on-Demand jet
A method of jet dispensing where individual drops
of material are formed at the end of a fluid jet.
The drop is formed by the forward momentum of
the fluid being ejected out of small orifice. The jet
is typically formed by rapidly changing the volume
of a filled chamber of material [4]
DOD
Dot-on-Dot - Dispensing droplets on the same
target area, either partially overlapping or
significantly covering the previous dispensed dot
DND
Dot-next-to-Dot - Dispensing successively droplets
in a given printed area in a side-by-side pixel
manner [15]
DDA
Dot-on-Dot-Always - Dispensing always two
droplets of smaller ink volume than utilized in
the DOD approach, onto the same target area [15].
Banding
Optical or/and physical differences in absorption,
media surface temperatures, etc. between leading
ink droplets and consecutive ink droplets cause
stripes perpendicular to the media movement
direction.
Seaming
The presence of sharp discontinuities in apparent
luminance at each band boundary (i.e. the border
between the lowest row of a first print swath and
the upper row of the next print swath) [16]
Fiducial Mark
a printed board artwork feature (or features) that
is created in the same process as the printed circuit
board conductive pattern and that provides a
common measurable point for component mounting
with respect to a land pattern or land patterns [5]
Legend
A format of lettering or symbols on the printed
circuit beard; e.g., part number, component
location and patterns [2]
C.O.P.
Cost Of Performance
CSP
Chip Scale Packaging
SMOBC
Solder Mask Over Bare Copper
BACKGROUND OF THE INVENTION
The present and ongoing trend of miniaturization and sophistication in electronics and the proliferation of electronic devices in almost all aspects of modern technology have led to stringent demands on the manufacturing of electronic equipment. Mass production of complex systems, incorporating steadily increasing component density in a competitive environment, required automated volume manufacturing procedures of electronic equipment.
The platform that fixates, connects and interfaces most electronic components with each other and with other elements in inter alia, computers, communication devices, consumer electronics, automated manufacturing and inspection equipment, is the printed circuit board (PCB) or printed wiring board (PWB). The manner in which these circuit boards are manufactured and the procedure of inserting and connecting multiple components of large variety (inter alia, resistors, capacitors; and integrated circuits), can be applied in mass production environments, achieving substantial automation, which results in costs reduction, high reliability and high component packaging densities. Backplanes and panels (interconnecting boards, in which printed circuits, panels or integrated circuit packages can be plugged or mounted into or onto) are also manufactured in a similar manner.
Whilst in the beginning of PCB usage, PCB's embodied substantially few components and moderately simple connecting path structures, modern highly dense populated boards require sophisticated and high resolution manufacturing techniques with precise registration capabilities.
To understand the technology of the present invention, a brief discussion follows of the prior art of a common manufacturing process of PCB's and in particular, solder masks and legend process.
Briefly, a PCB at the onset of the manufacturing line constitutes a base of insulating material on which a thin copper layer is laminated or plated, known as a bare copper plated board. A chemical etching step removes selectively areas of the copper to produce paths, which are electrically conducting. This selective removal is achieved by covering the copper layer with a patterned mask (etch-resist) that protects the copper layer in the following etching step. Generally, screen-printing techniques are utilized to form the patterned mask in low end PCB's. In high-end, more densely populated PCB's having generally complicated multi-layer conducting paths, Liquid Photo Imageable etch and solder resist mask procedures (discussed in more detail below) are commonly utilized. UV curing and subsequently developing produced resist masks with predefined patterns. The pattern that remains on the board after the etching step is commonly known as the primary image conductor pattern.
Whilst etch resist masks protects the areas of the conducting paths during the above-mentioned etching step, the solder resist mask protects the conducting paths from being coated with solder during the soldering step. The soldering step commonly connects the components leads to predetermined positions in the conducting paths (commonly called lands or pads) by fixating the leads and the conducting paths, utilizing a molten metal alloy, which after solidifying, achieves a permanent electrically conductive bond. In mass production commonly wave-soldering methods are utilized. In wave-soldering the PCB passages through a molten solder wave that coats the pads and leads and thus forms the required solder joints. The solder resist mask leaves only the pads uncovered that need to be covered by the molten solder, otherwise, also the conducting paths would be covered with solder, causing several p
Sadowski Benjamin
Sagi Dan
Zohar Ron
Fitch Even Tabin & Flannery
Printar Ltd.
Von Buhr Maria N.
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