Every supplier publishes a minimum package size, and it is nearly always a smaller number than the one their line comfortably holds. Here is what the numbers mean, what each end of the spectrum demands, and the case that causes more trouble than either extreme — a board that uses both.
Imperial codes are US-origin; the metric sizes are what actually appears in layout tools. Both are given because supplier datasheets use them interchangeably.
| Imperial | Metric size | Typical use |
|---|---|---|
| 01005 | 0.4 × 0.2 mm | Dense, space-constrained designs. Real yield risk, and effectively impossible to rework by hand. |
| 0201 | 0.6 × 0.3 mm | The practical floor for most products that also need serviceability. |
| 0402 | 1.0 × 0.5 mm | The workhorse of compact consumer and industrial boards. |
| 0603 | 1.6 × 0.8 mm | Still the most common size overall, and the easiest to work with. |
| 0805 | 2.0 × 1.25 mm | Where hand assembly and prototyping start to be realistic. |
| 1206 | 3.2 × 1.6 mm | Higher power dissipation, and a common choice for hand-assembled prototypes. |
| 1210 / 1812 | 3.2 × 2.5 / 4.5 × 3.2 mm | Where a passive needs to handle real current or act as a fuse. |
| 2010 / 2512 | 5.0 × 2.5 / 6.4 × 3.2 mm | Current sense, power resistors, high-value capacitors. |
The placement machine is the least of it. Four things have to be right before the first one is on the board.
An aperture for an 01005 pad is small enough that how the stencil is cut matters more than how accurately the machine moves. Fine-aperture work needs laser cutting with tight tolerances, and the foil thickness has to be chosen so the aperture's area ratio still releases paste cleanly. Get that wrong and you get inconsistent paste volume — which shows up later as either a tombstone or a void, not as a stencil problem.
Paste is graded by particle size, and the rule of thumb is that the largest particle should be no more than a fifth of the aperture width. A paste that is perfectly good for 0603 will not reliably print through an 01005 aperture. This is a supply decision, not an equipment one — the same machine can run both, but not with the same paste.
Small parts are light enough that too much placement force will damage them or displace them, and their thermal mass is so low that they reach reflow temperature almost immediately. Both need to be dialled in for the specific part, and the profile that suits them is not the profile that suits the rest of the board.
There is no point placing a part you cannot verify. Resolving a joint on an 01005 needs inspection resolution to match, and it is one of the reasons optical inspection alone is not enough on dense boards — see what each inspection method can and cannot see.
In practice this shows up as a yield problem on the small parts near the big ones, and it is usually solved by layout rather than by process: keeping large thermal masses away from fine-pitch clusters, adding thermal relief on large pads, and not placing a critical 01005 in the shadow of a connector. These are design decisions, so they are cheapest to make before the board is laid out — which is what a DFM review is for.
Ball pitch is the spacing between solder balls under a BGA, and our range runs from 0.3 mm to 1.25 mm. At the coarse end a BGA behaves like any other fine-pitch part. At 0.3 mm the substrate stops being the limiting factor and the process does: paste volume per ball has to be controlled tightly, stencil apertures shrink to the point where the paste particle size from above matters again, and the only way to see whether a joint formed is X-ray — an optical check cannot see under the package at any resolution.
Two practical consequences. First, a single 0.3 mm-pitch BGA on an otherwise ordinary board moves that board onto a different process setting and a different inspection plan, so it affects price out of proportion to its footprint. Second, it is worth asking whether the part needs to be that pitch at all — an 0.5 mm or 0.65 mm BGA is often pin-compatible in the same family and materially easier to build.
Choosing 01005 where 0402 would fit — you pay at the stencil, the paste, the profile and the inspection, and you buy only board area.
A single 0.3 mm-pitch BGA among coarse-pitch parts, when a coarser variant exists.
Large thermal masses placed next to fine-pitch clusters.
Fine-pitch parts on both sides of the board, which doubles the stencil and the reflow passes over the delicate one.
The largest package your layout and electrical requirements allow.
One fine-pitch cluster rather than several spread across the board.
Thermal relief and dedicated copper on large pads.
Keeping the smallest parts on the side that reflows second, so they pass through the oven once.
No, and often you should not. Package size is usually chosen for board area or for a specific electrical reason, not as a target to beat. If a 0402 will fit and work, a 0402 is more robust, cheaper to source, easier to rework and less likely to tombstone than a 0201. Going smaller costs money at every stage and buys you area — nothing else.
It is not the placement itself — modern machines place them accurately. It is everything around it: a laser-cut stencil with fine enough apertures, solder paste with the right particle size, a placement force light enough not to damage the part, a reflow profile tight enough not to tombstone it, and inspection equipment that can actually resolve a joint that small. Any one of those missing turns into a yield problem.
Yes, and it is the most common real difficulty on a mixed board. Reflow has to heat a large connector's thermal mass through to its joints without overheating a 01005 sitting a few millimetres away. The window narrows as the size difference grows, which is why mixing the extremes on one assembly is harder than a board that uses only small parts or only large ones.
Which inspections can see a fine-pitch joint, and which are blind to everything under a package.
Including the pick-and-place file that lets us check your component positions before production.
Every published limit: layers, line width, drill sizes, board dimensions and placement capability.
If your design uses a small package or a fine-pitch BGA, send it before you commit to the layout. We will tell you what the line can hold, what it will cost, and whether a coarser part would do the same job.
