Component availability can force a manufacturer to make a choice: delay building boards until all components are on-hand, or build what you can and hand-solder when they get in.

Sometimes, it’s called “building short.” The practice can seemingly offer a way to make the best of a less-than-optimal situation, but has pitfalls that have to be borne in mind. Hand-soldering, of course, is a risk compared to the surety of automation in a selective soldering machine.

Is this a viable practice? It might be…but you need to know what you’re getting into.

Hand Soldering Has Its Place

Automation has replaced hand-soldering for almost all electronics manufacturing, but there is still a place for it.

Boutique manufacturers or custom fabricators of certain electrical components or products that manufacture on a small scale can use hand-soldering without having too many issues. Output is usually low enough for quality control to catch any defective units for rework.

It may also be the case that occasionally one or two components here or there can be hand-soldered as a touch-up measure instead of as a primary method of soldering components.

However, some manufacturers either frequently or occasionally have to resort to an incomplete build due to component availability. What can be assembled on the board is soldered, either in a reflow oven or selective soldering system, and then finished by hand when parts are available.

What pitfalls exist for this practice?

Hand Soldering Lacks Repeatability And Requires Precise Tooling

Consistency and quality of product are of critical importance to manufacturing any product; when a PCB is a critical part of a control system – such as in an automobile or aircraft – even more so.

Hand soldering is not consistent to the same degree that an automated process can be. The human hand lacks the unerring certainty of machinery and therefore the exact same solder joint cannot be replicated.

While that doesn’t mean that the possibility of error becomes unavoidable, the frequency of error will increase, and not only that, keeps increasing every time a component is soldered by hand.

The more boards have to be finished by hand soldering, the greater the chances of an error in soldering, and the process of testing solder of electronic parts can become even more time intensive as error rates increase.

Not every manufacturer has the tools necessary to make the precise joint required for the boards and components.

Tip geometry and temperature control are both important when creating a solder joint. A soldering iron that retails for less than $20 may lack the proper tip shape for the joint that needs to be made and be set to the wrong temperature for the board, component and soldering wire.

To Build Short Or Increase Lead Time, That Is The Question

The manufacturer encountering a component shortage or cycles of availability faces the choice of either building short and taking a chance on hand soldering, or putting off all production until components are available.

In either case, lead time is increased, which may or may not be feasible depending on the circumstances. That has to be weighed by the business in question.

However, it’s also the case that the more times hand soldering is done, the more chances are taken on a poor connection and the need for rework or worse, failure of the board. Minimizing those risks is the superior choice.