Some boards pass every electrical check, simulate beautifully, and even function in the lab—yet still fail where it hurts most: cost, yield, and scalability.
These are economic failures, and they’re usually discovered far too late.
By the time they surface, the design is frozen, suppliers are chosen, and schedules are locked. Fixes become painful, compromises pile up, and margins disappear.
When PCBs Don’t Fail Electrically — They Fail Economically
Many late-stage PCB issues aren’t caused by “bad design” in the traditional sense. They’re caused by design decisions made without manufacturing context.
Common surprises we see late in the process include:
Trace/space that works perfectly in CAD but pushes fabrication into advanced (and expensive) process classes
Stackups defined around theoretical performance rather than real fab capability
Hole tolerances tighter than necessary, quietly killing yield
Over-specified impedance control on nets that don’t truly need it
None of these necessarily break the board electrically.
They break the business case.
And once they’re discovered—often during quoting, DFM review, or pilot production—the cost is already locked in.
The Real Problem: DFM Happens Too Late
In many workflows, DFM is treated as a post-layout checkbox:
“Let’s finish routing, then we’ll see what the fab says.”
At that point, every DFM comment translates into:
Rework
Schedule slip
Or higher unit cost
True DFM isn’t a sign-off step.
It’s a design input.
The most impactful DFM decisions happen before layout begins—when changing direction is still cheap.
DFM Checks That Should Happen Before Layout Starts
Here are the manufacturing checks that deliver the highest ROI when done early:
1. Fabricator Capability Alignment
Before a single trace is routed, confirm:
Minimum trace/space (inner vs outer layers)
Via types that are truly standard vs “available at a premium”
Drill aspect ratio limits
Designing to generic CAD rules instead of real fab limits is a fast path to unnecessary cost.
2. Stackup Defined by Reality, Not Theory
Stackup choices quietly set your cost floor.
Number of layers vs actual impedance needs
Standard laminates vs exotic materials
Copper weights that balance performance and yield
A beautiful theoretical stackup can be expensive to manufacture at scale.
3. Hole Strategy and Tolerances
Ask hard questions early:
What is the minimum finished hole size that truly matters?
Do these tolerances add functional value—or just risk?
Which holes must be plated?
Over-tight hole tolerances are one of the most common silent yield killers.
4. Controlled Impedance Reality Check
Not every fast-looking signal needs tight control.
Which nets genuinely require impedance control?
What tolerance is actually necessary?
Are reference planes continuous?
Over-specifying impedance is a classic cost multiplier with little real-world benefit.
5. Component and Footprint Manufacturability
Before locking footprints:
Are pad sizes and soldermask openings standard?
Do fine-pitch BGAs match available assembly processes?
Are via-in-pad assumptions aligned with filling capability?
Footprints are much harder to fix later than routing.
6. Board Outline and Panelization Assumptions
Board shape decisions affect far more than mechanics:
Odd outlines, cutouts, and castellations
Assembly rails and tooling
Edge clearance constraints
Outline decisions made late often force expensive compromises.
7. Test Strategy (DFM + DFT)
Manufacturing and test are inseparable:
Test point access and spacing
Probe side limitations
Flying probe vs fixture assumptions
If it can’t be tested efficiently, it can’t be manufactured economically.
A Simple Rule That Saves Money
Here’s a guideline we use constantly:
If a design decision doesn’t clearly improve signal integrity, power integrity, or reliability—question it from a manufacturing perspective.
Complexity is easy to add in CAD.
It’s expensive to remove in production.
Design for Value, Not Just Function
The most successful PCB designs aren’t just electrically correct—they’re manufacturable, scalable, and economically robust.
That outcome doesn’t come from better DRC checks at the end.
It comes from asking the right DFM questions before layout even starts.
If you shift DFM upstream, you don’t just avoid surprises—you design in margin.
Ready to Reduce PCB Surprises?
If you’re navigating complex requirements, tight schedules, or production risk, Comtec Labs offers a full suite of services to streamline your workflow: