Printed circuit boards
Introduction of printed
circuit boards
I. INTRODUCTION
In the current printed circuit manufacturing
technology, whether using dry film photoresist (dry
film) or liquid photoresist (wet film) process, is
inseparable from the photographic negatives;
existing traditional Printed Circuit photogravure
and optical imaging technology on printed circuit
boards (PCB) of the impact of the quality, how to
overcome the many abuses in the process of talks is
the theme of this paper.
2.Traditional PCB
manufacturing process defects
Beginning from the 1980s, PCB manufacturing
technology to achieve a photting machine or
laser photting replacement of traditional
painting (with) Chart / Photo Technology, this
revolutionary change simplifies the tedious PCB
production of the original black-and-white
technology, enhancing the PCB production
quality, and shorten the manufacturing cycle and
thus by the PCB industry widely welcomed.
However, in the computer / photting machine
photogravure film optical scanning, still need
to silver-based film of photogravure (SO CR
plate or film); from photogravure to-film
imaging (precision lithography exposure) of this
Process still exist in the PCB manufacturing
precision, the destructive elements, which are:
(1) silver-based film photogravure
1. To nitrification fiber, cellulose acetate
film base for the photogravure film its very
poor dimensional stability, even if the use of
polyester film-SO film, if not the ambient
temperature and humidity control, it is
impossible access to high-quality photographic
Deban;
2. By the computer / laser-scanning machine
painted after the photogravure film darkroom
processing (image, fixing, washing, etc.) in
addition to damage human health technology, the
process is very cumbersome at the same time, if
operating properly, photographic film will have
fog, discolouration or viscosity fingerprints;
3. Silver-photogravure film emulsion layer of
the main ingredient is silver bromide and silver
chloride and silver iodide (see Figure 1), in
the light of their role in the reduction of
silver nuclear centre. If the PCB manufacturing
technology in the use of silver-based
photogravure film can save a substantial amount
of precious metals - silver.
Figure 1 Schematic diagram of the structure of
photographic film
4. Silver-based photographic film anti-scratch,
anti-crease capacity is low;
5.Developing, fixing a large number of spent
washing, water resources, while also causing
environmental pollution;
(2) Exposure Machine precision and optical
imaging
Vacuum to make photographic film and the
photosensitive pre-coated corrosion-resistant
materials of PCB substrate (CCL layer) is
closely attached precision Exposure Machine most
important one of the technical requirements, and
its purpose is to obtain high-quality anti -
Erosion graphics. However, a detailed analysis
of this exposure process, it still can be found
there is an irresistible selection of quality
defects factor because of the process from
exposure light source (UV lamp) to the PCB
photosensitive layer of corrosion-resistant
materials to be irradiated path through the
center We do not want to have a two-tier
"isolation layer," one of the vacuum fixture in
the polyester film and glass plate and the other
for the camera film polyester film base, if a
photosensitive dry film as a corrosion-resistant
materials, exposure also more than a "barrier" -
covering dry film of polyester film. It should
be said that such a form of work is not entirely
satisfactory, and the ideal working conditions
are exposed photosensitive light
corrosion-resistant materials and direct
contact. (If the exposure light source contains
a relatively large number of non-collimated
light, or not parallel light, the light that is
not sensitive to vertical incidence
corrosion-resistant materials on the surface,
then the light from the camera will be below a
regional Deban black side-with the result that
the map like distortion). PCB exposure in the
process in the light refraction, diffraction
effects PCB problem is the quality of imaging is
a stubborn order as Naotou problems. If the PCB
manufacturing technology in the camera
deliberately stick Deban / vacuum exhaust
exposure process, the impact of the malpractice
exposure image quality is inevitably overcome.
In the manufacture resolution (or fine wire
diameter) 0.075 (0.050 mm PCB processes, we can
completely abandon the camera exposure Deban and
precision machine and creating a completely
different from the traditional PCB manufacturing
technology of the new PCB manufacturing
technology? will be answered in the affirmative.
3. PCB to discuss new technology
1. Figure 2 Figure process for PCB (graphics /
plating process of etching as an example.
Flowchart A traditional process, the new process
flow chart B).
From the A, B comparison of the two plans in the
process we could find:
（1）New Process (flowchart B) has been cancelled
camera Deban production process;
（2） In the traditional production process
(flowchart A) photosensitive dry film image
transfer is the need for precise exposure
(vacuum to dry film photo Deban and Tiejin), and
B has been cancelled in the process of the
precision of exposure (Icon said free exposure),
the image is in direct inkjet wetlands have been
pre-coated membrane (screen printing process)
have been put up dry film or the CCL board.
CAD cabling textures Deban black-and-white
photographic map
Duplex CCL NC blanking plate hole bored of the
whole metal-copper plate photosensitive dry film
image transfer graphics graphics electroplating
copper electroplating pewter to plug plating
film etching processing thermography test
appearance of the printed solder paste printing
Symbol finished marking system
CAD / CAM graphics Inkjet Printer
Duplex CCL NC blanking plate hole bored of the
whole metal-copper plate or patch Screen
Printing following exposure to the same A
process
A flow chart (traditional process) flowchart B
(New Technology)
Figure 2 Figure PCB Process
2, PCB to discuss new technology
(1) electronic engineering CAD
At present, the PCB industry has been widely
used CAD / laser painted in the computer system
is to use the commercialization of electronic
CAD / CAM software to help design, auxiliary
production PCB. From the original manual mapping
to the computer graphics, computer cabling to
automatically with the simulation of intelligent
automatic routing. From the traditional CAD PCB
design flow chart (see Figure 3) "production
data generation," we can see that "Light
drawings" a so-called "optical mapping" is
photting machine to the development of
high-precision and high speed, Laser Mapping
System operations, Israel Orbotech's photting
system is representative, in the past required
more than 10 hours photographic film, as long as
Shibanzhongzuoyou now be completed, and accuracy
can be as high as 0.003 mm. In the new
electronic engineering CAD, photting-drawn
machine or laser system has been replaced by
inkjet.
(2) Printing System
Inkjet system is an electronic engineering CAD
inkjet device driver (the device has a very
sophisticated piezoelectric nozzles) has been
coated corrosion resistance of the
photosensitive material CCL board inkjet
printing we need graphics (a special coating),
its resolution can be as high as 1000 (2000 DPI
or above, the inkjet image quality precision,
graphics edge steep, Tinggua.
Laws schematic schematic building (schematic)
simulation network connections automatically
generated table layout of the production data
cabling automatically generated graphics T-shape
cutting-board test drilling graphics
automatically mount
The logic devices (components and build
components characterization) produced documents
supporting documents manually assisted manual
wiring layout
Figure III CAD PCB design flow chart
(3) computer-to-plate technology demonstration
This paper addressed by the electronic
engineering CAD / inkjet system is actually
computer-to-plate technology or call
PCB-to-plate technology, which although in the
past some of the PCB in Xian occasionally
mentioned in the domestic real practical input
The reports are rare. Perhaps the high price of
the system (each system at about 2 million yuan)
affect its application. Currently, the system is
at least worthy of following PCB industry to be
discussed:
A, practicality
The applicability of the system and excellent
operating performance is undoubtedly welcome by
the PCB industry, and the electronic (automated)
operation is very simple and can be effectively
overcome in the process of the existing PCB many
solid disease. We are here to be discussed
"practical" actually is to stress the discussion
to promote computer-to-plate technology and its
advantages for PCB industry more people know it
and understand it.
B: Economy
Computer-to-plate technology PCB production,
the cost of manufacturing is more traditional
low PCB production technology, the initial
investment in equipment is too expensive.
However, according to author my humble opinion,
this high-priced equipment will be substantial
price cuts are inevitable, and that we can from
the computer and related information technology
products prices dropping lower and lower in
recent years the general trend in will be able
to understand, For example, in the late 1980s, I
purchased a set of CAD / laser Plotting System
spent a total of over 30 million dollars, and
now again if the purchase of a similar system,
in particular the performance quite good
homemade laser Plotting System ( 650 × 508mm
graphics format, resolution 2540 DPI, the whole
scan time 14'00 ", positioning accuracy 0.0008
(0.001 inch, the minimum line width from 0.002
inch) the price only 10 yuan (20 million, for
example, to buy a 1993 - 386 models of
computers, the market price of 20,000 yuan to
more than 586 now buy one of these computers,
the price only 6,000 yuan or even lower from the
computer-to-plate technology hardware (inkjet)
equipment to analyze , the equipment and
information products in the inkjet printer and
the number of core technical difference between
the current price inkjet printers only around
2,000 yuan, therefore, PCB computer-to-plate
equipment substantial price reduction trend is
irreversible, The only question of time it
sooner or later. high-tech products if the price
is always high above there were few buyers, its
lead to the "suffering" I am afraid that the
high-tech products is the main designer and
manufacturer. shows that the law of market,
similar to PCB Computer-to-plate technology from
the high-tech products will be high-priced to
the value of their return.
(4) inkjet system working conditions
A, in the screen printing industry, has Luschev
Switzerland, and other countries and companies
for platemaking mesh network computer-to-plate
system into practical use, from the precision
piezoelectric inkjet nozzle system in emissions
Some hot wax, and some special paint (ink). On
the PCB manufacturing technology, we are only
asking for a paint spray painting can be
effectively shielded coverage requirements,
corrosion-resistant materials can be
photosensitive, so, from the production of cost,
we do not want to PCB computer-to-plate system
choice expensive jet painted coating.
B, because the coverage in the paint directly on
the photosensitive corrosion-resistant
materials, so their exposure, without the use of
vacuum fixture, as long as the exposure light
source suitable choice can be, PCB workers need
not worry about such a process may be exposed
side-diffraction , and other defects.
4. CONCLUDING REMARKS
PCB camera Deban not only is the current
platemaking technology printed circuit
manufacturing technology an integral part of
innovation. At present, this innovative and new
changes have taken place that in the PCB CAD /
CAM segment will also eliminate inkjet system,
the computer will directly drive a special
cluster light (laser) has been pre-coated
directly to a special photosensitive
corrosion-resistant materials of Copper Clad
plate scanning (hereinafter referred to CAD /
laser scanning). I recall several decades ago,
we had just entered the PCB manufacturing
industry , the manual design → painted (with)
Maps (the original black-and-white) → camera……
backward technology cycle in our minds hold on
deep imprint; today's PCB industry not only
completely eliminated the traditional
photogravure process and from the computer /
laser painting technology forward to the CAD /
inkjet technology then again CAD / laser
scanning technology into manufacturing, PCB
industry changes (especially in recent years) is
how great! All this should be attributed to the
PCB strong sense of innovation and innovation
desires! The coming of the 21st century is the
era of knowledge economy, innovation is the soul
of a knowledge-based economy! In the era of
knowledge economy, the PCB industry even greater
need for innovation, it is because it is the era
of knowledge economy due to the knowledge of the
confrontation intensified competition in the
market, a wide range of technological progress,
the pace of technological innovation will be
even more accelerated in such a competitive
situation, If the PCB industry is not responsive
to the trend of history, they have relaxed their
sense of innovation and the speed of innovation,
it will be impossible PCB manufacturing
technology and the rapid development of the
times, it is very likely to be the era of train
Feishi thrown out of the vehicle. Continuing to
pursue a very aggressive PCB plot the road ahead
in the centre, we should always bear in mind -
continuous innovation!
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