According to the temperature profile for the Sn63Pb37 solder paste, a completed reflow soldering process contains the following stages: Preheat Zone: The heating rate in the preheat zone should be 2°C to 4°C/second and the peak temperature in this zone should be 100-125°C. During preheat if the temperature ramp is too fast, the solder paste may splatter and cause solder balls. Also, to avoid thermal shock to sensitive components such as ceramic...

We decided to order to different types of thermocouple, one bared wires and one with round insulators. The bared wire thermocouple is the BARE-20-K-12 with AWG wire size of 20. The thermocouple with double hole round insulator is the DH-1-24-K-12 with AWG wire size of 24. This one uses the DH-1-24 insulator, which can endure the temperature up to 1600°C (2900°F). Also today I tried to implement the LCD display using the Arduino Redboard....

On the same graph with the 3 data plots that we gathered last week, I put in the ideal profile temperature using the estimation method. I also made some studies about the solid state relay to better understand how it works and functions. A solid state relay is an ON-OFF control device in which the load current is conducted by one or more semiconductors, like a power transistor or thyristor. Like all relays, the SSR requires relatively...

Now that we have all the performance’s information about the two ovens, I combine all the data into one single graph to see which one performs the most efficiently and eventually makes the final decision. Also today I started playing around with the Arduino toolkit to try get used to it. The main part of the toolkit is the Sparkfun RedBoard, which is one of a multitude of development boards based on the ATmega328. It has 14 digital...

As our old toaster oven is too big and doesn’t seem to be efficient enough for the project, we decided to buy a new and smaller toaster oven which we hope would provide a better heat transferring rate. My task for today is to test this new toaster oven. Following the temperature profile, we want our oven to be able to heat up to the peak of around 440F over the minimum time of  2.5 minutes and the maximum time of 5.5 minutes. I tested our...

Today I did a bit of research on the MAX6675 K-thermocouple that we decided to use and I found the following resource: Link: http://datasheets.maximintegrated.com/en/ds/MAX6675.pdf Basically, the MAX6675 performs cold-junction compensation and digitizes the signal from a type K-thermocouple. The data is output in a 12-bit resolution, SPI-compatible, read-only format. Some key features of the MAX6675 are: Direct Digital Conversion of Type -K...