Q1: What is a Quad Flat Pack?
A Quad Flat Pack, or QFP, is an integrated circuit package that has a relatively small lead pitch (distance between centres of the pins) and has gull wing type pins which sit on the circuit board pads like feet. A PQFP is a Plastic Quad Flat Pack. This means that the body of the packaging of the integrated circuit is made from plastic. Most QFPs have plastic bodies anyway but "PQFP" is often just shortened to "QFP".

Q2: Why would I want to solder my own Quad Flat Pack?
If you are soldering a small batch or circuit boards or if you are soldering your own prototype then you may want to solder your own quad flat pack device to either save outsourcing costs, which can be substantial, or to save the turnaround time involved in outsourcing. Saving the turnaround time in outsourcing means that you can have your boards quicker.

Q3: What kind of flux should I use when soldering quad flat packs, and other fine pitch components with gull wing leads, J-leads, etc.?
You should use no-clean gel flux for the best result. "Liquid flux" generally does not have enough "rosin" or "solids content" for a good result.

Q4: What is a "reservoir tip"?
It is a tip for a soldering iron that has a small concave cavity in the end. Solder is fed into the cavity before soldering. It stays there by surface tension. When the tip is brough into contact with the pins of the device, the solder flows out onto the pins and circuit board pads. As the tip is moved along, surface tension allows all the pins to be soldered without bridging. It is a kind of "mini wave soldering" process. This method is also sometimes called "the drag method" for soldering quad flat packs.

Q5: Why would I want to use a toaster oven for soldering?
Many tech people and advanced hobbyists have found that using a toaster oven is a low cost and very effective way to solder surface mount components. On a small scale, and especially for small batches or boards or prototypes, it can be an alternative to using more expensive oven reflow equipment.

Q6: How do I solder using a toaster oven?
To solder chip components in a toaster oven, solder paste is first applied to the circuit board. Then the chip components are placed. The board is then put into the oven to heat, which activates the flux in the solder paste and allows the solder in the paste to melt and form the solder joints. Some temperature monitoring and control is desirable for this process.

Q7: How do I monitor the temperature inside the toaster oven?
Using a thermocouple and a digital thermometer. The thermocouple looks like a long wire with a connector on the end. The connector end plugs into the digital thermometer outside the oven, and the other end goes around the edge of the oven door and into the oven cavity.

Q8: What is "solder pot soldering"?
Solder pot soldering is essentially a process of dipping a board into a molten volume of solder. This is often used as an alternative to "wave soldering" in which the solder is actually pumped to create a wave over a barrier - the circuit board is then pulled over the wave to solder the bottom of the board. Solder pots can be different sizes. The Super Soldering Secrets website shows a technque for using an ordinary stainless steel frying pan as a solder pot. This is an excellent and low cost alternative to commercially available solder pots which are generally very expensive.

Q9: Where can I get more resources and information?
You can log in to the Super Soldering Secrets website to get 5 free videos on quad flat pack soldering. There is also an offer for a gold membership which has 16 videos revealing valuable tips, tricks and techniques.

If you have a soldering question, please email anthony@supersolderingsecrets.com