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What does PCB drilling create?

PCB drilling creates openings for electrical interconnections, component leads, mounting and other mechanical functions. Mechanical drilling and laser processing serve different feature types and constructions. The correct requirement is not simply a drill diameter: it includes the finished size, plated or non-plated function, depth or layer span, positional relationship and any subsequent filling or finishing operations.

For a plated hole, the opening produced before metallization differs from the finished opening after copper and relevant processing. For a microvia, the geometry and process route differ from a conventional mechanically drilled through hole. The PCB manufacturing process guide places drilling within the complete route; this page focuses on the data and geometry needed to make those holes correctly.

Start with the function and the layer span

These categories are not merely names for different diameters. The start and stop layers determine when a feature can be made. A buried connection may be processed in a subcomposite before the final board is laminated. A sequential HDI construction can require repeated drilling, metallization and bonding stages. Review the route before assuming that every hole can be added at the end.

The HDI PCB guide owns the broader build-up and microvia construction decision. This drilling page helps document the features, but it does not turn a conventional through-hole calculation into a microvia reliability model.

If the first decision is whether a wall must conduct, use the PTH versus NPTH file and function review. For elongated openings, distinguish plated slots for terminals from mechanical slots and cutouts; their geometry may look similar while their electrical requirements differ.

From released drill data to a prepared hole

The fabrication data must identify units, hole functions and the correct revision. Mechanical drilling uses a qualified combination of machine, tooling, support and process parameters for the actual laminate stack. Laser processing depends on the dielectric and copper construction and the intended feature. Neither route should be selected from hole diameter alone without considering the material and span.

The resulting opening can contain debris or process residues and expose resin, reinforcement and copper edges. Hole preparation and desmear are therefore important parts of the interconnection route. The treatment must suit the material system. A method suitable for one epoxy construction may not be appropriate for every PTFE, flex or hybrid stack.

illustrates that mechanical and laser processing are separate equipment families. separates surface preparation and the initial conductive route. These are process references; they do not establish which machine or chemistry is assigned to a particular 吃瓜tv order.

Finished hole, preplate opening and annular ring

If copper is added to both walls of a circular hole, the free diameter decreases. A simple geometric estimate adds twice the entered wall build to a desired finished diameter to estimate the earlier opening. Real tool selection also accounts for preparation, processing and size tolerances. Therefore the estimate is useful for understanding the relationship, not for overriding the fabricator's drill compensation.

The annular ring is the copper remaining around a hole in a land. In a simplified concentric model, radial ring width is half the difference between land diameter and hole diameter. Relative displacement between the hole and land consumes margin on one side. Finished-board acceptance can involve specific definitions and locations, so identify the convention before comparing a worksheet result with a standard or drawing requirement.

For example, a 0.30 mm finished hole with an entered 25 碌m wall build gives a 0.35 mm preplate estimate. A 0.60 mm land then has 0.125 mm nominal radial space around that estimated opening. Subtracting 0.075 mm relative registration leaves 0.050 mm in this illustrative geometry. These numbers are not a 吃瓜tv minimum or a universal IPC limit.

Review a circular-hole planning envelope

Enter the required finished diameter, an assumed or agreed wall build, land diameter, relative registration allowance and actual drilled span. The worksheet returns the simple preplate estimate and geometric ring. It also reports two aspect-ratio conventions so the denominator is never hidden.

The depth-to-diameter ratio can use the actual drilled opening or another explicitly stated convention. Two suppliers may appear to quote different ratios if they use different denominators. Always ask which dimension is meant. For blind or buried structures, the relevant depth is the span being processed, not automatically the final board thickness.

The model assumes circular, straight-sided geometry and a uniform entered wall build. It excludes drill wander along depth, local hole shape, differential material effects and the actual plating distribution. A positive ring margin does not prove a reliable interconnect. A negative result is a clear geometric review flag, not an instruction to reduce copper requirements.

Release drill and mechanical data without ambiguity

Separate plated and non-plated requirements clearly in the manufacturing output and drawing. Identify slots and their finished dimensions; do not assume that a row of drill hits is an unambiguous slot definition for every receiving system. Show countersinks, counterbores or depth-controlled features on the appropriate side with meaningful datums and tolerances.

For a component hole, consider the finished lead or pin requirement and the assembly process. A press-fit interface may need a different tolerance and verification approach from an ordinary soldered lead. Do not copy a generic via specification onto a mechanically critical connector hole. Review the component manufacturer's requirements and the complete board construction together.

For non-plated mounting holes, define the relationship to nearby copper and the finished edge. A hole that fits a screw can still conflict with a washer, enclosure feature or insulation requirement. The mechanical drawing should make these interactions visible before the fabrication route is released.

For recessed hardware, the countersink depth worksheet relates the cone to board thickness, while countersink versus counterbore compares the seating detail against the actual fastener. A larger local recess retaining a floor belongs to the cavity depth and protected-layer review. Supply a section and named entry face for these features.

Drilling and plating share a specification boundary

The drilled geometry influences access for hole preparation and copper build. The copper process then changes the finished opening and forms the connection to the relevant layers. Treating drilling and plating as unrelated purchase notes can produce a contradiction between the desired finished hole and the required wall copper.

The plating PCB guide explains why surface copper and hole-wall copper require separate evidence. A surface measurement does not automatically establish the deposit inside a hole. If a filled or capped via is required, identify the fill type and final surface construction as additional requirements rather than assuming they follow from a small drill size.

What should drilling verification establish?

Review size, position, shape and connection-related features according to the agreed acceptance plan. Finished dimensions should be measured at the defined stage using the applicable method. Structural evidence may be needed to examine internal layer junctions or the completed hole-wall construction. The appropriate coverage and sampling depend on the board and order requirements.

The identify rigid-board qualification and performance topics, including interconnection-related features. Use the applicable purchased standard and drawing requirements to establish acceptance, rather than copying a single number from an unrelated online capability table. This page's geometry examples are explanatory and are not acceptance tables.

Keep the original released hole requirements and the approved manufacturing response together. If the fabricator changes a tool diameter to achieve the required finished hole, that is different from changing the customer's finished-size requirement. A clear record prevents an internal compensation value from being mistaken for a new product dimension.

Which drilling choices affect price and delivery?

Hole count, diameter mix, depth, material, slots, controlled-depth work and interconnection sequence can affect manufacturing effort. A small number of unusual features can matter more than many straightforward through holes. Sequential structures can add process cycles and verification beyond the drilling operation itself.

Provide the actual drill schedule and stackup with the quotation request. Highlight press-fit holes, blind or buried spans, backdrilling and critical mechanical tolerances. If a feature is negotiable, explain its function so an alternative can be reviewed without weakening the product requirement. A quote based only on the smallest drill size misses important context.

Use the PCB DFM review to organize broader manufacturing questions. For a fabrication response, send the released data through PCB Manufacturing. The hole worksheet can support that discussion, but customers with complete drawings can enquire directly.

PCB drilling questions