Effect of moon phase on tombstoning

20220914 - 22:55 - no tombstones.

Here are some pictures just to spice it up a bit. Nothing remarkable happened.

Paste still done with the same stencil that I received at the beginning of this project:

Place parts:

Food grade reflow process:

Done:

20220907 - 20:11 - no tombstones.

20220901 - 21:30 - no tombstones.

20220809 - 22:01 - no tombstones.

I was on vacation, hence the little gap since the previous log.

20220710 - 18:46 - no tombstones.

20220703 - 21:29 - no tombstones.

20220625 - 23:33 - no tombstones.

So far I've only assembled some boards and noted problems that occured. Let's give all that some context.

First of all, in order to see what effect the moon phase has (note: I'm not phrasing this as an "if"!), we need to calculate the phase, at least roughly. At this stage I don't it matters much if we're slightly off.

One lunation (see here: https://en.wikipedia.org/wiki/Lunar_month) takes 29.530589 days on average, and we can calculate the number of lunations since january 1st, 1923 (full moon, roughly) for a given day by dividing the days that have passed since then by those 29.5xxxxx days. Great. The remainder is the number of days within the current lunation. We can use that to calculate the phase (as a fraction), again by dividing by 29.5xxxxx days.

For a first overview, I created a plot for all assembled boards. Each point in the following plot represents an assembled board. The lunation starts at x=1, y=0 (full moon) and evolves counter-clockwise. Waning moon is in the top half (x=0, y=1 would be half moon) and waxing moon in in the bottom half, new moon is to the left (x=-1, y=0).

There are some obvious gaps but they'll hopefully vanish over time. These were all boards, so what about those with problems? Here we go:

Lo and behold, that's a pattern. But let's not jump to conclusions about the reasons now. I still have tons of resistors here!

20220619 - 23:18 - no tombstones.

The paste was a bit runny on the 360 Ohm resistor:

All was well in the end, but this is the third time something's happening that's related to the 360 Ohm resistor. I cannot but see a pattern forming here.

20220610 - 23:43 - no tombstones.

New paste this time, but that didn't change anything.