Lesson · Problem 18
Make It Manufacturable
The board still has to be built
You should be able to
- Name courtyard, silk, edge clearance, drill, and annular ring as separate build checks.
- Repair a seeded defect without creating a short.
DFM / Manufacturing · PCB Fundamentals
What it is
Design-for-manufacture checks in this challenge are specific seeded issues: silk over pads, parts too close, copper too close to the edge, a via drill below the 0.30 mm minimum, a trace narrower than 0.25 mm, missing test points, and a polarity mark on the anode side of the LED. Annular ring is the copper donut around a drilled hole. It is checked in the final compliance run. Enlarging a pad does not fix a drill that is too small. Clearance here includes part-to-part and copper-to-edge, not only trace-to-trace.
Why this matters
A circuit can be electrically right and still be rejected by a fabricator, or assemble crookedly, because of spacing and geometry.
What you are building
A board with seeded manufacturing defects: silk, spacing, edge copper, a small drill, a narrow trace, missing test points, a polarity mark.
Prerequisites
This lesson uses courtyard, via, pad, trace width, clearance, board outline, polarity. It introduces annular ring, drill, copper-to-edge, silkscreen, DFM.
Component guide
What the parts are. The requirements panel is still the list that is graded.
Annular ring
- What it does
- The copper donut left around a drilled hole.
- Why it is here
- Too little and the pad can break out. A larger pad does not enlarge a drill that is too small.
- Symbol
- A via or a through-hole pad.
- Beginner mistake
- Enlarging the pad and leaving a 0.20 mm drill under a 0.30 mm minimum.
- What an engineer checks
- Minimum drill and minimum ring are different lines in the requirements.
Courtyard
- What it does
- The keep-out around a footprint so parts and the board edge stay clear.
- Why it is here
- Two courtyards that overlap will not assemble cleanly.
- Symbol
- A dashed box around the part, larger than the pads.
- Beginner mistake
- Nudging every part by the same amount and creating a new overlap.
- What an engineer checks
- The courtyard clearance the rule states.
Interview lens
Annular ring and minimum drill are different sentences. Say both.
What PCBGrade measures
Each seeded defect as its own rule, then a compliance pass. Silk does not join a net.
Where this shows up
A fab note is this list. Electrical connectivity does not cancel it.
Terms
- Annular ring
- The copper that remains around a hole after the drill. Too little and the pad can break out.
- Courtyard
- The keep-out area around a footprint so parts and the board edge stay clear.
- DFM
- Design for manufacture: rules that make the board buildable, beyond “it simulates”.
What is happening electrically
A fabricator drills, etches, and routes to tolerances. The annular ring is the copper that remains around a hole after the drill wanders. Too little ring and the pad can break out, so the connection opens even though the schematic was right. Copper near the board edge can be cut when the outline is routed. A courtyard is the space a part and its assembly need. Silkscreen on a pad prints ink where solder should wet.
Why the geometry matters
Each of those is a different measurement. Enlarging a pad can grow the ring and still leave a drill that is smaller than the process allows. Moving a part to clear silk can create a new short or a courtyard crash. Nudging every part by the same amount does not read the failed rule.
How an engineer reasons
Read the measured value and the required value on the rule that failed. Repair that feature. Then run the check again, because a DFM repair can break connectivity. Electrical correctness and manufacturability are both required. Passing one does not imply the other. Annular ring, drill, copper-to-edge, courtyard, and silk are five different features. A fix for one of them is not a fix for the others.
Worked example
Each seeded issue is its own rule with its own points. The final compliance check is the design-rule run after the repairs. The requirements panel is the list.
Good and bad
A via with a legal drill and a ring that meets the limit, silk off the pads, courtyards inside the outline, and copper back from the edge: the board can be built and the circuit is still connected. A beautiful route with a 0.20 mm drill fails the drill even if you grew the pad. Silk that “labels” a pad is not a connection and is a soldering defect.
Common mistake
Nudging every part by the same amount, or deleting a trace to silence a clearance error.
Where this rule stops
The numbers in this challenge are the seeded rules: drill, ring, edge, courtyard, silk, width, test points, polarity. A different fabricator publishes a different capability. The principle that survives is: ask which physical feature failed, and do not treat a manufacturing rule as a substitute for the circuit, or the circuit as a substitute for the build. A board that simulates and cannot be drilled is unfinished. A board that meets every fab rule and shorts two nets is also unfinished. Growing a pad can help the ring. It does not enlarge a drill that is already below the stated process minimum. Silk on a pad is ink, not a net.
Before the challenge
The challenge seeds specific build defects. Repair the one the failed rule names. Moving everything by the same amount is not a repair.
Ready for the challenge
You can read a failed rule, change that geometry, and check you did not create a short.
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