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project:beta-layout:etchbath [2012-10-03 23:56] ZafhBuJLZgoh
project:beta-layout:etchbath [2012-10-04 01:03] (aktuell) alte Version wieder hergestellt
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-It'​s ​posts like this that make srfunig so much pleasure+====== pcb-pool etch bath ====== 
 +{{tag>​project hardware electronics pcb chemistry howto}} 
 +  * Flower vase 
 +  * 50W aquarium heater 
 +  * Aquarium air bubble thingy with pump 
 +  * 3D-printed top and PCB holder 
 +Note: the PCB holder doesn'​t have much grip.  The 3D-printed screws are also a bit difficult to tighten/​loosen. 
 +====== Modifications ====== 
 +===== PCB Holder ===== 
 +The PCB holder already has some grooves to better hold the board. However, these weren'​t wide and deep enough to really hold on to the board so we've simply used a saw and widened them a bit. 
 +===== Heating-element ===== 
 +The heater is a simple aquarium heater. ​ By design the peak temperature is 37C controlled by a bimetal switch. 
 +This temperature is not high enough for [[https://​​wikipedia/​en/​wiki/​Sodium_persulfate|sodium persulfate]] (Natriumpersulfat) etching. 
 +The mod overrides the bimetal switch and puts the heating element into an always-on mode. 
 +A temperature sensor element was also fitted inside the heater just above the heating element to measure the approximate temperature of the heating element. ​ There'​s ​a [[http://​​gallery/​index.php/​Projekte/​pcb-pool-equipment/​etchbath/​10k3950|conversion table for sensor resistance to temperature]]. 
 +Tests showed ​that controlling the temperature is not necessary, since the heating element peaks at around 55C and begins to slowly (read: several minutes) oscillate between around 45C and 55C. 
 +The modified heater was able to raise the temperature of the etch batch to around 47C which is a nominal increase of around 10 Kelvin over the unmodified off-the-shelf model. 
 +[[http://​​gallery/​index.php/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4199|{{http://​​gallery/​var/​thumbs/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4197.jpg}}]] Soldering in the bimetal override. 
 +[[http://​​gallery/​index.php/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4199|{{http://​​gallery/​var/​thumbs/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4199.jpg}}]] Fitting a temperature sensor inside the heater. 
 +[[http://​​gallery/​index.php/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4200|{{http://​​gallery/​var/​thumbs/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4200.jpg}}]] Fixating the sensor using hot glue. 
 +[[http://​​gallery/​index.php/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4201|{{http://​​gallery/​var/​thumbs/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4201.jpg}}]] No more temperature dial, just the cables for override and temperature sensor.  
 +[[http://​​gallery/​index.php/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4202|{{http://​​gallery/​var/​thumbs/​Projekte/​pcb-pool-equipment/​etchbath/​DSC_4202.jpg}}]] Test-driving the modified heater. 
project/beta-layout/etchbath.txt · Zuletzt geändert: 2012-10-04 01:03 von