Placing parts
AUpdated v2.4.4At a glance
- One picker searches every mounted library plus the parts this document already owns — parts you own rank first
- The library carries one Resistor, not ten thousand — pick the class, type the value, choose the footprint variant
- Every row shows JLCPCB and PCBWay stock, Basic-vs-Extended class and a qty-100 price before you commit
- Multi-unit parts are first class: four gates of an LM324 come out as U1A through U1D, one package
- Reference designators are assigned as you place, and Reannotate renumbers a whole board in reading order
- Rotate and mirror the ghost before you drop it; double-click the reference or the value on the sheet to retype it
- Values are typed the way an EE writes them — 10k, 4u7, 100nF, 4k7, 2n2
Press A or Place Part and the picker opens. Search by name, keyword or category; the results carry a live symbol preview, so you can see what you are about to drop before you drop it.
Your project library — the parts this document already owns — is listed first and outranks everything else. A part you have already used is almost always the right pick, and picking it again costs nothing.
Concrete parts and discrete classes
The library holds two kinds of thing, and the difference is what stops it from being a hundred thousand near-identical entries.
A concrete part is a specific device: an NE555P, an LM324N, a 2N3904. Its name is its
value and you don't type one.
A discrete class is a family: Resistor, Capacitor, LED. The library carries one of these,
not one per value. You pick the class, type the value, and choose which footprint variant
you want — a ¼W axial on 0.4" pitch, an 0805, whatever the part offers. The value lives on the
placed part; the footprint choice lives there too. As you type, the vendor part number resolves
live underneath, so a 10k that nobody stocks in the package you picked tells you so at placement
rather than at order time.
Values parse the way you'd write them on paper: 10k, 4.7u, 100nF, 4k7, 2n2, 1meg,
10 kΩ. Case follows the industry — M is mega, m is milli, u is micro.
Stock, before you commit
Every row in the picker shows what JLCPCB and PCBWay have: stocked or not, Basic or Extended (Extended means a per-unique-part loading fee, which is real money on a small run), and a qty-100 price. A filter hides anything not stocked, at either house or at one.
It never blocks a pick. An unstocked part is a decision, not an error — and if you make it, the bill of materials says "source yourself" on that line instead of inventing a match. Full detail in Designing around what's in stock.
Dropping it on the sheet
The part follows the cursor as a ghost. R rotates it 90° clockwise, Shift+R counter- clockwise, M mirrors it, Escape puts it back. Pin connection points show a snap ring as you pass them, so you can land a part directly onto an existing wire end.
Reference designators
A designator is assigned the moment you place, from the part's own prefix — R, C, U, Q.
Nothing already on the board is disturbed by it.
Multi-unit parts are handled properly. An LM324 is four opamps plus a power unit. Place four
gates and you get U1A, U1B, U1C, U1D — one package, four units — not four separate chips.
Place a fifth and it rolls to U2A, because the package is full. The power unit is placed once and
carries the supply pins for all of them; if you place gates and never place it, the rules check
tells you (missing_power_unit), because nothing else in the design would.
Reannotate (Shift+A) renumbers a whole board or one sheet in reading order — left to right, top to bottom — when the sheet has drifted after a lot of editing. To set one by hand, double-click the designator text on the sheet and type; it is checked for uniqueness across the whole board, and units of one part are correctly not treated as duplicates.
Editing what's on the sheet
Double-click the value to retype it (the vendor match re-resolves), the reference to rename it. Both labels drag independently of the symbol on a 50-mil grid, so a dense corner can be made readable without moving the part. Right-click a part for Properties…, which is where declared properties, a pinned manufacturer part number, DNP and BOM exclusion live — see Part properties and datasheets.