Two Hours to get a PCB? Really?
No. At this time, TwoHourPCBs is a philosophy, not a promise. Perhaps someday technology will permit that. Though a single-sided PCB can be printed and baked in a bit under two hours, there is set-up time. Set-up time includes things like downloading and checking the gerber files. Preparing the board for printing. Then the ink is baked for an hour, followed by burnishing away the chemicals which made the silver ink extrudable.
Our blog will have answers to questions you do not have yet. The blog should be especially helpful to anyone considering adding DPCB to their engineering department. In addition to DPCB helpful suggestions, you may be able to speed up your learning curve by studying our mistakes.
Review our services to see how we can help your in your experiment / prototype / small run electronics.
Of course you have questions. You have never seen this done before.
Our machine deposits solder paste on the finished pcb. Surface mount components are hand placed and then re-flowed. After this, through-hole components are soldered by hand with lead-free solder.
If you want to make any changes or additions to your PCB assembly you must use tin-bismuth-silver solder. Through hole components must be pre-tinned with this solder (they come from the factory 'tinned' with incompatible mixtures.) One must not use soldering equipment that has been used for tin-lead or ordinary lead-free solder. You may learn much more from our blog posts "learning to solder again."
Surface mount parts can be as small as 0603. But if you are experimenting and are likely to be changing some parts, 0805 or 1210 will be much more appropriate.
Minimum trace width is 0.25mm (0.01 inch [ 10 mil ]). Traces can be as wide as you like.
Pin pitch and clearances:
Minimum pin-to-pin pitch is 0.8mm (0.032 inch [32 mil]). With 32 mil pitch, use 16 mil trace width, which leaves 16 mil clearance. Trace clearance should be 10 mil minimum.
Current limits for conductive ink?
Conductive ink is pretty conductive, but, not quite as good as copper. If you have really high current traces (like 500 mA or more) that can be handled by designing your pcb with a through-hole point-to-point wire instead of a trace.
Vias can be made with conductive ink or rivets. Rivets for vias have a 0.9mm ( 0.035 inch) head diameter so design your vias at 90 milli-inch diameter. Drill size is 28 milli-inch.
SMD and through-hole?
Yes! For through-hole components, rivets are used instead of plated-through-holes. Your gerber should use 63 milli-inch hole diameter and o.d. of 90 milli-inch. Inner diameter of the rivets is 1mm (0.039 inch [39 mils]) and the rivet head diameter is about 2.25 mm (0.09 inch [90 mils].) Vias and rivets must not be placed under components ! We have designed boards with SMD underneath through-hole components by placing the through-hole components on headers.
Can you print silkscreen?
Rapid PCB prototyping technology does not currently provide the ability to print component placement and reference designators on your board. Board stuffing will require a paper-print of the top layer silkscreen for use by the assembler.
Is hand soldering 'different'?
To hand solder components or wires to the rapid-prototype pcb requires low temperature melting solder and lots of flux. We use tin-bismuth-silver solder and temperature controlled irons set to 170 to 180 degrees C. Conventional tin-lead solder will instantly damage the silver-containing conductive ink.
Solder re-flow only on one side
Components can be placed and re-flowed on one side of the board only (typically the 'top' side.) If you need SMD on the bottom side, they will have to be hand-soldered.
How large can the PCBs be?
The present limit of Rapid PCB printing is 100mm x 125mm (4.0 inch x 5.0 inch.) If that is not large enough you probably need to contact a traditional board-house. Alternatively, your circuit might be designed on multiple small boards and then connected together like a patch-work quilt.
Yes we can do "copper pour" with the silver conductive ink. However we strongly recommend instead of a solid pour that you design a hatch. Solid copper areas and copper pours can add a few hours to production time and requir great quantities of silver ink. For experiments and circuit testing, usually a copper hatch area will suffice.
If you really need a copper pour, then a CNC mill type of DPCB machine would be your choice. Whether a copper pour or a hatch fill, you will have to pay extra attention to thermal isolation of SMD pads. See note about ground planes, below.
Operating Frequency Limitations ?
The conductive ink operates well even at several GHz.
Ground / Power Planes ?
Depending on your requirements and circuit complexity, the solution is to print conductive ink on an FR4 board that is copper clad on one side (the bottom side.) Then connect the plane to the topside traces with either rivets or hand-soldered wires. This is easily accomplished with a single sided PCB design.
Stuffing and re-flow of SMD components on rapid-print PCBs requires a unique lead-free solder paste. If you have commercially made copper PCBs or have etched a copper PCB yourself, surface mount components use traditional tin-lead paste.
Design assistance ?
Over 40 years in electronics. Our forte is analog and RF design. We can advise you proper PCB trace techniques and component placement for proper circuit operation.