Question: I am trying to solder some 2N7000 MOSFETs onto a PCB that I got manufactured, but the pads are very close together. When I try soldering the first leg on the MOSFET, I always end up shorting it to the other pad through the solder. The soldering iron I am using is relatively thin and heating at a temperature of 300 C.

Could I be applying too much solder or are there other things you should do to prevent this?

Below are images of the top and bottom of the MOSFET pads, marked as Qx on the top of the PCB:

[![Top](https://i.stack.imgur.com/dE0Xl.jpg)](https://i.stack.imgur.com/dE0Xl.jpg)

[![Bottom](https://i.stack.imgur.com/MBx9u.jpg)](https://i.stack.imgur.com/MBx9u.jpg)

Answer: 
A smaller soldering iron tip and smaller diameter good quality solder would help. 0.8mm is a good compromise for through-hole parts, maybe with some 1mm and some 0.4mm for coarser/finer parts and SMT.

The design isn't great, it would be better to have the pads spaced out more (plenty of room) and to have to form the TO-92 leads. KiCad has such footprints defined.

Here, for example, is a tape containing pre-formed transistors (the once-ubiquitous 2SA1015 in a Y beta bin). They are formed to fit 3 pads on 2.54mm (0.1") centers. You may prefer to use a footprint with staggered leads.

[![enter image description here](https://i.stack.imgur.com/AfrJu.jpg)](https://i.stack.imgur.com/AfrJu.jpg)
There's two ways you can do this:

* Either use a very fine tip, fine solder 0.5mm or thinner, and carefully solder each via.
* Or (easier) just use a chisel tip, focus on making 3 good joints regardless of if they short with each other or not. Then apply plenty of flux with for example a flux pen and heat all 3 joints a second time.

---

> 
> Could I be applying too much solder
> 
> 
> 

Very likely since this is a classic mistake. Particularly using far too thick solder wire. There's a tendency to focus too much on which tip to use instead of just use thinner solder.

But also the layout isn't good and the CAD tool should warn against placing pads this close - the plated area looks too large. As mentioned in another answer there's all manner of TO92 leg shapes you can pre-order.