Single Layer PCB (1L)
The simplest, fastest and most cost-effective board there is: copper on one side only, no plated holes to connect. Here's exactly how a single-sided board is built, what it's made of, how to lay it out well, and which IPC classes and tolerances apply.
Copper on one side, substrate on the other
A single-sided board has conductive copper on only one face of the substrate — the other face is bare FR4. All components mount and solder on the copper side; through-hole component leads pass through the board but land on a pad on that same single copper layer. There's no second copper layer to connect to, so there's no plated-through-hole step at all — this is the single biggest process simplification versus every other board type on this site, and it's exactly why single-sided is the fastest and least expensive option to build.
Because everything has to route on one plane, the layout itself does more of the work: component placement, jumper wires and a deliberate ground pattern take the place of a second layer or an internal plane. It's a real design discipline, not just "the cheap option" — and for a huge range of products, it's genuinely the right one.
- LED drivers & lighting
- Power supplies and simple converters
- Consumer electronics — remotes, toys, appliance controls
- Sensor and relay boards
- Educational and low-volume prototype boards
The manufacturing process, step by step
Every step here happens on one copper face — there's no second layer to plate, register or test against, which is what keeps single-sided lead times short.
Panel preparation
Copper-clad FR4 laminate is cut to panel size and cleaned of oil, dust and oxide so the photoresist bonds properly in the next step.
Imaging
A photoresist film is applied to the copper, exposed to UV through the circuit photomask, then developed to reveal exactly the pattern that needs etching or protecting.
Etching
Chemical etching removes every bit of unprotected copper, leaving only the intended circuit traces behind; the remaining resist is then stripped off.
Drilling
Component-lead and mounting holes are drilled. On a single-sided board these are simple mechanical holes with no copper barrel — there's no second layer for a plated hole to connect to.
Solder mask
Liquid photoimageable solder mask is applied over the copper side, then exposed and developed to leave pads and holes clear while protecting the traces.
Silk screen
Reference designators, polarity marks and any required legend text are printed on the component side.
Surface finish
A solderable, oxidation-resistant finish is applied to every exposed copper pad so components solder reliably later.
Routing
Individual boards are routed or punched out of the production panel to their final outline.
Electrical test
Continuity and isolation are checked net by net — simpler than on a multi-layer board, since there's only one plane of copper to verify, but still checked on every single board.
Final QC
A final visual and dimensional check against the fabrication drawing, before packing.
FR4, copper weight and finish
The substrate is FR4 — a woven fiberglass cloth bonded with a flame-retardant epoxy resin, chosen for its mechanical strength, near-zero water absorption and stable electrical insulation. Its glass transition temperature (Tg) — the point where the resin starts softening — determines how much thermal stress it tolerates: standard Tg (~130–140°C) is plenty for most single-sided consumer designs; higher Tg only starts to matter once assembly runs hotter or more thermal cycles are expected.
| Copper weight | Thickness | Typical use |
|---|---|---|
| 0.5 oz | ≈17.5 µm | Fine-pitch signal-only designs |
| 1 oz | ≈35 µm | Standard signal traces — the default for most boards |
| 2 oz | ≈70 µm | Power paths, LED drivers — anything current matters on |
Since single-sided boards are often exactly the power-supply/LED-driver type of design that needs to carry real current, copper weight is one of the few material choices worth deciding deliberately rather than defaulting — every trace on a 1-layer board is, by definition, an outer-layer trace, which actually gives it roughly double the current-carrying capacity per unit width of a buried inner-layer trace on a multilayer board (per the IPC-2221 k-factor model). Surface finish is typically HASL-LF for cost-sensitive single-sided work — good solderability at the lowest price — with ENIG being the usual alternative where a flatter surface or longer shelf life is needed.
Layout & DFM guidelines for single-layer boards
One copper layer means the layout itself has to do the job a second layer or an internal plane would otherwise do.
IPC classes & quality standards
Even the simplest board type is qualified and inspected to the same IPC framework as a 6-layer one — just against a simpler set of features.
| IPC-6012 Class | Typical use |
|---|---|
| Class 1 | General electronic products — limited-life, simple-function consumer devices |
| Class 2 | Dedicated-service electronics — the de facto industry-standard baseline for most commercial production |
| Class 3 | High-reliability electronics — medical, military/aerospace, where failure isn't an option |
IPC-A-600 defines the visual/dimensional acceptance criteria that go with each class — base-material condition, solder mask coverage, conductor width/spacing, non-plated hole and edge condition are all judged against it. IPC-2221 is the generic design standard behind trace-width-vs-current calculations; for external-layer copper (which single-sided traces always are), its current-capacity coefficient is roughly double what an internal multilayer trace gets for the same cross-section.
Our real specs for single-layer boards
Everything above is general industry practice. This is what we actually build, in-house, in Iași.
| Board thickness | 0.51 – 2.4 mm |
| Copper weight | 18 / 35 / 50 / 70 µm |
| Glass transition (Tg) | 135 °C standard, 150 °C or 170 °C on request |
| Minimum track / isolation | 0.15 mm / 0.15 mm |
| Minimum drill | 0.3 mm (0.5 mm pad) |
| Maximum panel (1–2 layer) | 390 × 520 mm |
| Solder mask | Green, white, black, red, blue, yellow |
| Surface finish | HASL-LF (Pb-free, RoHS compliant) |
| Testing | 100% electrical test (short circuit and open circuit, flying probe) and AOI inspection on every board |
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