20230616: THE 65W MINI HOT PLATE
I chose this model because of its working area of 560mm x 560mm and also, it was the cheapest of the lot. Alternatively, there were options of other models and to look up the Internet and DIY/ Build my own. But this would mean getting new programming tools and components, and so on, which in the end, would cost more. Plus, I will need more time to get it up and running. This idea would be a drain on both resources since I am only using spare cash for this Hobby. In the end, this unbranded mini hot plate and the (separately bought) 65W 20V 3.25A Laptop Power Supply costs just a little under RM120.00.
For the time being, my intention is to cut down the soldering time for the 391mm diameter Razor Crest Engine PCB. Hand soldering a pair would take me hours. I have revised the PCB design to allow for reflow soldering by moving the 24 0603 LEDs a smidgen closer inwards. In the original prototypes, the plastic on the AMT Razor Crest keeps pushing and breaking the LEDs if you try to force it in.
The main issue was the unreliable way of soldering the tiny 0603 network resistors. Originally, I would rest the soldering iron tip on the network resistor which placed on top of the pre-tinned solder pads. The bit will heat up the whole component, and melt the solder below. It has a higher chance of success but at the cost of the component looking burnt because I was effectively burning it. However, after changing my soldering iron bit, the results were inconsistent. The reason I changed the bit was because it got rusted and bent. Yeah, this technique bents soldering iron bits. So, thinking a few steps ahead, the time to start doing reflow soldering is now, even if I start from a smaller scale.
20230620 THE HOT PLATE MENU
A few days later, the power supply arrived. This mini hot plate uses a USB-C interface for the power and it is located at the back, between the two tactile push buttons. The upper part of the hot plate consisted of three plates which I think the lower two are for cooling. My version of this hot plate uses countersunk screws and there are other sellers where the customers complained of different screws. I guess the hot plates were bought and then assembled by the sellers themselves, something like CKD (complete knock-down) cars here.
If you look at the hot plate, it has three small plates with a nice noticeable little heater at the uppermost metal plate. The other two I think, are for aesthetic and cooling functions.
The lower half white thingy was claimed as ‘High quality 3D printed material with no delamination’ and and they do warn of not to exceed 250ºC. Sadly, there are is are instructions in the box nor much information on the Internet too. So, I have to go in blind. Oh, boy.
Use the two buttons to scroll the menu and press them together again to SELECT.
Whatever you do at this stage, do not confirm this option for the time being. This is QUIT.
Press both buttons briefly and you will enter this section.
Press BOTH LEFT & RIGHT buttons until the menu confirms your selection.
Here, the initial setting was 350ºC since the Seller’s page warned of not exceeding 250ºC.
These are the ones which will define how the mini hot plate works, from the rising temperature rate, to the soaking time, to reflow time and then cooling. They are quite critical so that the PCB does not suffer from thermal shock.
In this case, CURVE option allows you customise the reflow process.
I am not sure what this is so the following three images are just speculation on my part.
Maybe this is the preheat/warming time of 103 seconds
Maybe this is the reflow time for 30 seconds
Maybe this is the plate’s cooling down rate of 30s, back to MIN TEMP of 000ºC (It will never go there but hovers at rooms temperature)
I pressed both buttons and it starts to go to the MAX TEMP.
IN SUMMARY
So, basically, I have a mini hot plate for reflow soldering and when time permits, I will need to look into its reflow programming before I can start using it properly. Also, I have gotten an infra-red thermometer which has a wider temperature range compared to a medical version. Although I am not sure if it has been calibrated but the temperature it read from the mini hot plate was about 50ºC or so off.
