PCB intelligent heating table_V2

 
B station video: https://www.bilibili.com/video/BV1WF411N7mS
 
 
First version link: (simple version without temperature control, very low cost)
https://oshwhub.com/xiaozyh/67Wxiao-xing-pian- xie-PCBjia-re-
 
 
QQ communication group, if you like electronic DIY, you can join if you are interested: 213795230
 
Compared with the first version, the second version has higher cost, and the corresponding functions are more complete, including temperature control and display screen. Buzzers, etc.,
the heating plate uses an aluminum substrate, and the wire pattern is a Hilbert curve, which can perfectly fill the entire plane.
Resistance and wire-related calculations:
First, the 1OZ thickness of Jialichuang is 0.035mm. The resistivity of copper can be calculated according to ρ = 1.75*10-8.
Assume that the width of the copper trace is w and the total length is L. Hilbert The unit length of the curve is d,
then R = ρ*L/S, where S = w * 0.035*10-3 
and R=U2/P, U is the voltage at both ends of the heating plate, it is known that P is the heating plate that needs to be designed The power is also known, so the resistance R required for the heating plate is determined
according to Hilbert curve law. It can be seen that L= (22n-1)*d.
If it is necessary to design a 50mm*50mm effective heating area board, according to Hilbert curve According to the law of the curve, d = 50/(2n), where n is the order of the Hilbert curve (just choose the appropriate one), then the value of d is determined.
Based on the above conditions, the width w of the wire can be calculated.
In summary , select the appropriate order of the Hilbert curve, and use the known unit wire length d and unit wire width w to determine the heating plane of a specific power.
Pay attention to unit conversion; in addition, when the power is relatively small, don't make the heating surface too large, otherwise the temperature will not rise. (Newton's law of heat dissipation)
  
 
also conducted a simple test
1. Temperature control, which is basically stable and reliable, and was compared with an infrared thermometer.
2. Raise the heating table to 180 degrees and heat for more than 20 minutes. The structure will not deform due to heat.
3. The actual welding operation was also carried out, and the effect was good.
 
This series is continuously updated, corrections and exchanges are welcome.
Question: This version of 78M05 feels a bit overheated (the board can be used normally). I will replace it with the next version. If you have a small size step-down chip, you are welcome to recommend it.
Other new features will be added in the next version.
 
QQ communication group, if you like electronic DIY, you can join if you are interested: 213795230