Choosing a PCB Printing Solution The electronics Printed Circuit Board industry
is evolving as new production technologies become available at low cost. Direct
digital printing is making inroads into the traditional photolithography and
screen printing processes that have been used to manufacture PCB for the last
twenty years. Here we will focus on the use of direct digital printing to
individualize PCBs just prior to their assembly. The goal is to print a unique
mark on each board that can be used to identify the board. The mark must be
permanent and will probably contain 1D or 2D machine readable codes along with
alpha numeric characters. The marks must have a 600 DPI (dots per inch)
resolution or better due to size constraints on the PCB. We will also focus on
applications that require more that 1,000,000 boards per year. At these volumes
automated material handling starts to become very important to the overall
success of the system. High volume PCB fabricators use screen printing with
thermally cured ink to print the legends that cover each side of the board. At
this time digital printing can not print the whole side of a board at a price
that competes with screen printing.Thermally Cured Ink A startup company in Israel
“Printar” has introduced a printer targeted at low volume, fast turn PCB
fabricators who need to reduce the cost and lead time associated with small lot
screen printing. Interesting is their thermally cured ink that reportedly has
better adhesion capability than other ink systems. Advantages Good Ink Adhesion
? Disadvantages Requires Large Oven For 350-400 deg F Heat Cure Does Not Include
High Volume Material Handling Piezoelectric Drop On Demand Digital Printing PCB Prototype, UV Cured Ink Markem
Corporation has developed an ink/print head system ( the Model 4000, see here )
that several OEMs and integrators are using to print on PCBs. The system uses an
ink that is less viscous at high temperature and almost solid at room
temperature. The print head operates at 68 deg C, the ink drops cool when they
contact the PCB becoming almost solid. This allows the system to print fine
detail on PCBs without ink running or smearing. When exposed to UV light the ink
undergoes a chemical reaction becoming a solid plastic like substance. The cured
ink is impervious to common solvents. Advantages Competitive Incremental Cost
High Contrast With Fine Detail (600 DPI) Before Cure, the Ink Can Be Wiped Off
And the Board Reprinted After cure, The Ink Can Not Be Removed Except By
Scraping High volume Material Handling Available Works Well With Inline
Inspection (Inspect Before Cure, Cure Only Good Boards) Disadvantages Ink
Adhesion Can Be A Problem On Certain Substances Requires the PCB Be Clean (No
Finger Oils) Standoff Distance Less Than 2mm, Suitable For Unpopulated Boards
Only The PPS 7000 The PPS7000 has been designed to print individualizing marks
on PCBs using option 6. The system uses a SMEMA compatible edge belt conveyor to
move PCBs to the print area where they are printed and optically inspected Rigid flex PCB. After inspection they
are conveyed to the inline curing station and then out the back of the machine.
When being automatically loaded by a board destacker, panels exit the system
about once every 10 seconds. Each panel usually contains multiple boards that
each receives a unique serial number. The overall throughput of the machine is
highly dependent on the number of boards in each panel. The more boards in each
panel the higher the throughput in boards per minute. A drag and drop WYSIWYG
(What You See Is What You Get) programming system has been developed that allows
a new panel to be programmed in approximately 5 minutes. An offline programming
system is also available. We are the only PCB board marking system that creates
a permanent (solvent resistant) high contrast mark, incorporates SMEMA
compatible high volume material handling and incorporates inline inspection.
Next Steps If the PPS7000 looks like it may meet your requirements the next step
is to print samples for you in order to verify that the ink will adhere well to
your substrates. © 2006 by Prototype & Production Systems, Inc. Free for
unlimited distribution as long as this copyright notice and link to
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