| -- End Ad Box ---> | | | | Particle Generation May Require A Cleaning Step |
| The electronics Printed Circuit Board industry is | | | | Piezoelectric Drop On Demand Digital Printing, Solvent |
| evolving as new production technologies become | | | | Based Ink |
| available at low cost. Direct digital printing is making | | | | For a concise description of drop on demand digital |
| inroads into the traditional photolithography and screen | | | | printing see here. In my opinion this option represents a |
| printing processes that have been used to | | | | slight improvement over option 2. |
| manufacture PCB for the last twenty years. | | | | Advantages |
| Here we will focus on the use of direct digital printing | | | | Competitive Incremental Cost |
| to individualize PCBs just prior to their assembly. The | | | | High Contrast Mark |
| goal is to print a unique mark on each board that can | | | | Many Colors Available |
| be used to identify the board. The mark must be | | | | Easier Process To Control Than Continuous Ink Jet |
| permanent and will probably contain 1D or 2D machine | | | | Disadvantages |
| readable codes along with alpha numeric characters. | | | | Standoff Distance less Than 2mm, Suitable For |
| The marks must have a 600 DPI (dots per inch) | | | | Unpopulated Boards Only |
| resolution or better due to size constraints on the PCB. | | | | Solvents May Be Released Into Atmosphere, Many |
| We will also focus on applications that require more | | | | Companies Trying To Reduce Solvent Emissions |
| that 1,000,000 boards per year. At these volumes | | | | Mark Not Resistant To Some Cleaning Solvents |
| automated material handling starts to become very | | | | Piezoelectric Drop On Demand Digital Printing, |
| important to the overall success of the system. | | | | Thermally Cured Ink |
| High volume PCB fabricators use screen printing with | | | | A startup company in Israel “Printar” (see here) |
| thermally cured ink to print the legends that cover each | | | | has introduced a printer targeted at low volume, fast |
| side of the board. At this time digital printing can not | | | | turn PCB fabricators who need to reduce the cost |
| print the whole side of a board at a price that | | | | and lead time associated with small lot screen printing. |
| competes with screen printing. Even though many | | | | Interesting is their thermally cured ink that reportedly |
| printers, including the PPS7000, could print all the | | | | has better adhesion capability than other ink systems. |
| nomenclature on the board, here we will focus on | | | | Advantages |
| using digital printing only to print the individualizing marks. | | | | Good Ink Adhesion ? |
| Several individualizing options exist including the | | | | Disadvantages |
| following: | | | | Requires Large Oven For 350-400 deg F Heat Cure |
| Preprinted Label Application | | | | Does Not Include High Volume Material Handling |
| Many low volume products start with labels printed on | | | | Piezoelectric Drop On Demand Digital Printing, UV |
| office equipment and hand applied to each PCB prior | | | | Cured Ink |
| to or after assembly. As the product volumes ramp | | | | Markem Corporation has developed an ink/print head |
| the reliability and cost of hand applying labels becomes | | | | system ( the Model 4000, see here ) that several |
| a problem. Automated systems that print and apply | | | | OEMs and integrators are using to print on PCBs. The |
| labels are available. (see this site ) Because of PCB | | | | system uses an ink that is less viscous at high |
| space constraints these systems must place labels | | | | temperature and almost solid at room temperature. |
| very accurately, a big problem for many label | | | | The print head operates at 68 deg C, the ink drops |
| application systems. The labels are not permanent. At | | | | cool when they contact the PCB becoming almost |
| high volumes the labels are more expensive than other | | | | solid. This allows the system to print fine detail on |
| marking methods. | | | | PCBs without ink running or smearing. When exposed |
| Advantages | | | | to UV light the ink undergoes a chemical reaction |
| Low Initial Cost | | | | becoming a solid plastic like substance. The cured ink is |
| High Contrast Mark | | | | impervious to common solvents. |
| Disadvantages | | | | Advantages |
| Not Permanent | | | | Competitive Incremental Cost |
| Higher Incremental Cost | | | | High Contrast With Fine Detail (600 DPI) |
| Difficult to Change Label Size On The Fly | | | | Before Cure, the Ink Can Be Wiped Off And the |
| Mechanical Complexity For Automated Application | | | | Board Reprinted |
| Solvent Based Continuous Ink Jet Digital Printing | | | | After cure, The Ink Can Not Be Removed Except By |
| Continuous ink-jet technology has been adapted to | | | | Scraping |
| mark on many industrial products including PCBs. With | | | | High volume Material Handling Available |
| these systems a continuous stream of ink droplets is | | | | Works Well With Inline Inspection (Inspect Before Cure, |
| steered to the desired location using electromagnetic | | | | Cure Only Good Boards) |
| fields (see here ). Solvent based inks produce | | | | Disadvantages |
| permanent marks on porous surfaces. The marks are | | | | Ink Adhesion Can Be A Problem On Certain |
| less permanent on non-porous surfaces where | | | | Substances |
| smearing may be a problem for the short time its | | | | Requires the PCB Be Clean (No Finger Oils) |
| takes to dry. | | | | Standoff Distance Less Than 2mm, Suitable For |
| Advantages | | | | Unpopulated Boards Only |
| Competitive Incremental Cost | | | | The PPS 7000 |
| High Contrast Mark | | | | The PPS7000 has been designed to print individualizing |
| Many Colors Available | | | | marks on PCBs using option 6. The system uses a |
| Disadvantages | | | | SMEMA compatible edge belt conveyor to move |
| Complex Ink Viscosity Process Can Be Difficult To | | | | PCBs to the print area where they are printed and |
| Control | | | | optically inspected. After inspection they are conveyed |
| High Resolution (Greater Than 300 DPI) Difficult To | | | | to the inline curing station and then out the back of the |
| Achieve? | | | | machine. When being automatically loaded by a board |
| Solvents May Be Released Into Atmosphere, Many | | | | destacker, panels exit the system about once every |
| Companies Trying To Reduce Solvent Issues | | | | 10 seconds. Each panel usually contains multiple boards |
| Mark Not Resistant To Some Cleaning Solvents | | | | that each receives a unique serial number. The overall |
| Laser Ablated Ink Patches | | | | throughput of the machine is highly dependant on the |
| Many industries use lasers to engrave marks onto a | | | | number of boards in each panel. The more boards in |
| variety of parts. Lasers have been used to engrave | | | | each panel the higher the throughput in boards per |
| marks onto PC boards with limited success due to the | | | | minute. A drag and drop WYSIWYG (What You See |
| lack of contrast of the resulting mark. A newer | | | | Is What You Get) programming system has been |
| approach is to have the circuit boards printed with ink | | | | developed that allows a new panel to be programmed |
| patches, the ink patch is then selectively removed | | | | in approximately 5 minutes. An offline programming |
| (ablated) by the laser creating the mark to be printed. | | | | system is also available. |
| (see here ) PPSI has the capabilities to develop a laser | | | | We are the only PCB board marking system that |
| based marking system. | | | | creates a permanent (solvent resistant) high contrast |
| Advantages | | | | mark, incorporates SMEMA compatible high volume |
| Competitive Incremental Cost | | | | material handling and incorporates inline inspection. |
| High Contrast Mark If Ink Patch Is Used | | | | Product Brochure |
| Very Fine, Highly Reliable Marks Available With Laser | | | | Next Steps |
| Galvo Head | | | | If the PPS7000 looks like it may meet your |
| Disadvantages | | | | requirements the next step is to print samples for you |
| High Initial Cost | | | | in order to verify that the ink will adhere well to your |
| Requires Preprinted Ink Patch | | | | substrates. |
| Even At Low Power Laser heat May Damage (by | | | | Please contact us to arrange for printing samples. |
| Fracture) Traces, Causing Intermittent Reliability | | | | Our address is: |
| Problems | | | | Prototype and Production Systems Inc. |