Selective soldering – is it for you?
The vast majority of PCBAs we manufacture at NOTE Windsor are now double-sided, mixed technology with both surface mount technology (SMT) and through-hole (TH) components. To guarantee repeatability and reproducibility of the TH soldering we use our ERSA Versaflow 345 selective soldering line. This enables us to tackle increasingly complex PCBAs; and specifically boards which must be manufactured to the IPC-A-610 Class 3 standard.
The Basics Remain Much The Same
Despite the myriads of component types, diverse and complex nature of technology now, essentially the basics have not changed…much.
Every piece of electronic equipment we use contains a level of soldering, whether it be PCBA or wiring. Historically, all of this was known as plated through-hole (PTH) soldering often done on a wave soldering machine or by hand. With the advent of surface mount technology (SMT), the whole world changed with the introduction of reflow ovens, and later vapour phase ovens.
Most, but not all products today will have a mix of these two technologies and component geometries on the board. Whilst SMT devices are fairly straightforward to solder using reflow or vapour phase, we often get asked the best way for soldering through-hole devices.
There are multiple ways of approaching through-hole soldering including wave, selective wave using pallets, manual and selective soldering, but the latter two are by far the most common.
Manual soldering offers you a wide range of flexibility, but the disadvantages are the time it takes, i.e. cost, the opportunity for human error, and most important the repeatability and quality of joints.
Our selective solder systems deliver consistent and repeatable solder joints to IPC-610 Class 3 if required. There is a place for manual soldering, where you encounter flying leads that need to be soldered to the board for example. But in the majority of cases, most through-hole components can be soldered using a selective system providing thought has been put into design and component selection. Real benefit comes when you have connectors to solder as the nozzle can whisk along the rows of joints faster than you can manually.
Top Tips for Selective Soldering
- Where the design permits allow 2-3mm gap between components.
- Ensure thermal relief is designed into the layout especially where you have ground planes.
- Keep 5-6mm from the edge of the board.
- Check the thermal range of components on the board as it reaches 260 during this process.
- Consider the weight of heavier components that might tend to cause warping and need extra stiffeners.
- Ensure the board is panelised effectively to maximise the throughput.
We pride ourselves on ensuring that continuous improvement underpins everything we do and to achieve this. We continue to invest in new machinery and will soon be taking delivery of a second selective soldering line, growing our capability to deliver a quality on-time service.