Storing boards through a shutdown

A shutdown is the longest continuous stretch that boards sit unattended, usually in a building where the heating or cooling has been turned down to save money. Most of what goes wrong over that period was decided in the last hour before everyone left.

What changes when nobody is there

The climate. A building running at a controlled temperature and humidity during working weeks is a different environment once the systems are set back.

The problem is not the average. It is the swing. A room that cycles between a cold night and a warmer day will at some point bring surfaces below the dew point of the air around them, and that puts water on boards without a single drip appearing anywhere.

An unheated space over a long break is where that happens, and it happens repeatedly, once per cycle, for the whole period.

Floor life keeps running

Anything with an open moisture clock keeps accruing. Two weeks of shutdown is two weeks of floor life on every moisture sensitive assembly left out, and it will be spent before anyone is back to notice.

Boards with a live clock should be resealed with fresh desiccant or moved into a dry cabinet before the break rather than after it. That is the single highest value action on the list. There is more in floor life, baking and the rack in between.

Corrosion has time to work

Surface finish oxidation is slow, which is exactly why an extended idle period is when it becomes visible. Exposed copper and bare finishes that would be through the process in days are instead sitting for weeks.

Boards stored where the air moves and does not condense do considerably better than boards in a sealed box that trapped humid air in it on the last working day. Sealing something damp is worse than leaving it open.

The other risk is that nobody remembers

The practical failure after a long break is not damage. It is that the person who knew what was in which rack is not the first person back, and the boards left mid-process have no label explaining what state they were in.

Work in progress that stops mid-flow and sits for weeks is where boards get finished twice, or not at all, or scrapped because nobody can establish what happened to them.

Before the last person leaves

Reseal or move anything with a live moisture clock. Get boards off the floor and out of any position that sits against an outside wall or under a roof, because those are the surfaces that swing hardest.

Label every rack with what is in it and what the next operation is, not just what the part number is. Do not seal boards into containers on a humid day.

And write the date on it. The first job in January is establishing how long everything has been sitting, and that is a five minute job if somebody wrote it down and a half day of guessing if nobody did.

Racks with identifiable slots make that labelling straightforward, and slot-number label sets are in rack spares.