back to index

Thermochromic breadboard


Why
How
Todo

Why

When prototyping electronics, sometimes a part gets overloaded and the [link?:magic smoke] leaks, rendering it nonfunctional. If such event is not instantaneous and the heating progresses for longer time, this can be easily missed, the engineer is lulled into false complacency and ruins a part and/or burns his fingers.

A solderless breadboard is frequently used for such prototyping. One that can visualise the temperature of the parts would make the engineer's job slightly easier.


How

A solderless breadboard was chosen, and cleaned with tetrachloroetylene. (Acetone or any other solvent would do the job too.)

A set of three microencapsulated leuco-dye thermochromic pigments with different threshold temperatures and compatible colors, was obtained:

They were mixed together, yielding the color range of black-purple-red-white as the temperature increases over the thresholds.

The thermochromic composition, same as in the Thermochromic Silicone, was used, with the same epoxy binder as in the Thermochromic Kitchenware project. The resin was highly viscous, making the applied layer uneven. Heating with a hairdryer lowered the viscosity somewhat, slightly alleviating the issue.


Clean breadboard

First coat, hairdryer-heated

The cured coating was tested with a power resistor. It was shown that the uneven nature of the coating together with the rather low thickness and color intensity made the color change somewhat less obvious than desired.

The high ambient temperature of the summer day made brought the board above the first threshold, rendering it purple instead of black.


First coat, resistor heat test

First coat, resistor heat test

First coat, resistor heat test

First coat, resistor heat test

A second coat of the paint, with slightly higher pigment loading, was applied. After cooling in the fridge for a couple minutes it shown a nice even black color.


Second coat

Second coat, fridge-cooled

Two tests were done with power resistors, used as test sources of heat.


Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

A part can heat the board by direct contact and by heat conduction through the leads, but also by the thermal radiation.


Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Resistor test

Many of the little holes were plugged shut by the resin, or made slightly smaller. They were enlarged again with a 1mm drill bit.


Todo


If you have any comments or questions about the topic, please let me know here:
Your name:
Your email:
Spambait
Leave this empty!
Only spambots enter stuff here.
Feedback: