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THEORY OF OPERATION

A project log for Apache AL13P & TL-320b - One Pass PCB Toner Xfer

Single pass Lower Temp Toner Transfers. Now available as a DIY kit. Open Source, Dual laminator compatible!

mosaicmercmosaicmerc 11/21/2014 at 01:210 Comments

Theory of Operation

A document laminator is tuned to apply temperature and pressure suitable for sealing plastic pouches over paper and card stock. Heavier duty laminators can handle heavier pouches and heavier card and are capable of higher temperature operation. Print Toner is mainly pulverized plastic and melts within the range of laminator temperatures (around 150 Celsius) at the rollers.

In order to optimize toner transfer to copper clad board of various thicknesses and copper weight, the laminator must increase its temperature{, }pressure or both. This is usually achieved by using multiple maximum temperature passes; up to 20 times for a particular toner transfer to be of good quality with no drop outs on non optimized papers. This method is tedious and prone to repeatability issues based on such factors as the board length & thickness, copper weight, ambient temperature and the speed with which the board is returned to pass through laminator again. The thermal capacity of the copper clad and its cooling between passes is the variable here. Each additional pass increases the net temperature of the board to approach the roller temperature and re-presses the toner onto the copper.

The modification simply automates the multi-pass approach and adds both time & energy efficiency benefits while simultaneously enhancing both repeatability and safety. Relying on the 60 Hz A.C. synchronous motor speed, the linear motion of the rollers is controlled via forward & backward mini passes to achieve up to a 12:1 speed reduction of the original linear speed. No alteration to the rotational speed or torque is used. No tampering with the 120 VAC power is done. This provides a number of direct benefits such as: reduced roller hot spots as compared to 'stop & go' slowdown methods; repeatable roller speed versus triac based speed control; chopper methods of speed control which stutters a synchronous motor. Lastly, the best benefit is overlapping heat/pressure passes with insignificant copper clad board cooling in between; delivering energy and time savings.

The effectiveness of the approach is enhanced by the nature of the Apache AL13P control system which offers integral motor direction and temperature control. The modification leverages the features of the OEM control and does a minimum of alterations. Adjusting the tension of the rollers via the 4 bottom screws should not be required, limit doing this to a turn or two of tightening to avoid overloading the motor. The net result is reliable transfers using much less heat and pressure and time compared to other 'popular' laminator instructable type mods done before. Optimizations are possible for faster production by having more OEM temperature headroom in the laminator without hacking the heaters and risking a fire or laminator damage.

The modification circuit employs a small PIC 12F675 micro-controller to sense the OEM thermal sensor's condition as well as to control the timing of the roller motion and provides a simple man-machine interface for control. A beeper is included to provide for audible feedback or alerts based on the selected operation mode of the system or any alarm conditions. A thermal sensor failure will now result in an alarm sound and failsafe shutdown of the heater for safe operations.

All the features of the modification are optional and the laminator can serve its original purpose or switch to copper clad lamination or 'dry transfer foil to metal' at the touch of a button. The modification is integrated into the OEM controller seamlessly and utilizes the OEM DC power to operate. The modification's schematic details each pin function of the OEM controllers 6 pin cabling system for convenience of debugging. The mounting of the modification requires NO drilling, cutting or alteration of the laminator as it is mounted in an OEM provided fan cutout in the housing.

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