Hints for laminators:
Buy the largest size(the taller, the larger the diam of pressure rollers) home/office use laminator you can find that fits your budget, buy one that is rated for operation continuously and for thick laminations. I found a nice, small, used low-priced office unit on sale for USD 50 that worked great after mods.
Laminators with the largest diam large thermal mass and high laminating pressure rollers work best. A used quality older laminator bought could be better than the small-size cheaper newer home photo-lam models with small pressure rollers.
The laser printer used to print the artwork should be set for "coarse heavy paper" if possible to get the thickest toner deposited.
1) All unmodified laminators fail to reach a temperature necessary to optimally melt the toner so that is will transfer.
Note most laminators unmodified have one or more electric overtemp cutout switches that must be removed or shorted since they stop any temperature rise above 130 to 140-deg C.
I had to modify each laminator I first experimented with to get it to reach the higher temperature(180-DegC optimal for toner melt). I used the thermistor found attached to the heating plate to measure temp and set the right temperature.
I destroyed two cheap laminators before I learned to get a tall unit and then learned how to get hotter, but not meltdown hotter operation.
You must get the laminator to operate at a slightly higher temperature than the toner melt transfer temperature. A few degrees higher will cause the internal gears inside the laminator to soften or melt after many minutes of operation.
I built a MCU circuit to control the temperature by turning on/off the heating element TRiAC or relay and my MCU shows me with a LED when the laminator is ready. I used a thermistor chart to convert the thermistor resisitance reading into actual temperature measured voltage.
You need to set the temperature accurately. If you don't have someway to measure temperature, like reading the built-in thermistor or thermocouple, you must find a slower way by trial and error to set the lamination temperature high enough to melt toner.
2) After passing through the laminator for several minutes, an ideal paper must be able to easily disintegrate when soaked in water. I have best and consistent success with glossy lightweight photo paper.
Other papers, especially ordinary printer paper or magazine paper will give inconsistent and unexpected results.
The idea here is simple and most important, you need to remove completely the disintegrating paper which is holding the toner to be transferred. You must remove the paper completely and gently so only the toner sticking to the board is all that's left.
3)Board prep: You need to burnish(slightly scratch) the PCB stock with sandpaper to create more surface area(places) on the copper surface for the melted toner to bind to.
4)After sanding the PCB lightly, until you can easily see the fine scratch marks, you must clean the board with iso or denat to remove all dirt, and always use gloves to not allow skin oils to contaminate the board.
5)Before running the PCB through the modified laminator, bend the photopaper around the PCB and into a u-shape over the PCB and make sure the paper is pulled taught and secured on the back of the PCB with masking tape to make the best tight contact to the board.
6)Oversize the photopaper covering the board and fold it so that you can make u-shaped "wings" to fold over the back and bound securely.
7)When placing the PCB into the laminator, always feed the bottom of the u-shape in always first. When the paper emerges on the output tray, immediately take it out and feed in back in again but flip it over vertically top to bottom each pass.
8)After passing through the laminator, wetsand (using iso or denat) to saturate the back of the photo paper to remove the paper coating to hasten the paper's ability to absorb water and soak. You should easily see the paper turn soggy-looking. After this pre-soak, you can continue soaking in circulating (dripping)warm water. From time to time, the paper should be gently rubbed with your thumb to tell if the paper is ready to disintegrate into tiny pieces with only very light rubs of the thumb.
The cause of most failures of toner transfer is in this step is from being impatient and fail to soak the paper until it has become fully soft soggy disintegrated paper pieces.
8)My MCU controlled laminator goes into a warm-temp standby mode with a push of a switch. If you don't have this feature, turn the
laminator off immediately after laminating a PCB to minimize the change of overheating of the plastic gears to the point they soften and strip and melt.
9) If your attempt fails, you can always clean the toner off with fine sandpaper/steel wool/acetone and you can re-use the board. Be careful to not to use too much sanding pressure and begin to sand off the very thin copper surface on the PCB.
Home
Help
Search
Login
Register
