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Define exactly what is being measured

Vertical fill percentage compares a measured filled height with the relevant barrel height under a defined method. It is not the same as the percentage of the annular cavity's volume filled, the external fillet area or the percentage of leads that passed inspection. A single two-dimensional section samples one plane and does not reveal every void around the circumference.

Record the measurement method, viewing orientation and specimen identity. If an image cannot resolve the boundary, label the value uncertain rather than reporting a precise percentage. Inspection access and interpretation should be agreed before a production lot depends on a limit that cannot be measured consistently.

PTH annulus volume and measured fill

Keep hole size, lead shape and barrel height separate

Use the finished plated-hole diameter, actual lead cross-section and board/barrel height. A drilled-hole callout can differ after plating. For a round lead in a circular barrel, ideal cavity volume is pi divided by four, multiplied by the difference between hole-diameter squared and lead-diameter squared, then multiplied by height.

That model excludes external fillets, lead corners, eccentric insertion, local plating irregularities and void distribution. It is useful for comparing geometry, not setting wire-feed volume directly. A non-plated mechanical hole does not become a reliable PTH connection simply because solder has been added near it.

Follow the thermal path to the upper barrel

Copper planes, connected conductors, a heavy pin and the board thickness influence the heat required at the connection. Insufficient energy at the upper region can leave poor fill even when solder contacts the underside. Review product preheat and solder-contact evidence along with the thermal-relief or plane connection in the design.

Increasing solder-contact time is only one possible adjustment and can exceed component or board limits. A useful trial measures the affected location and compares it with an otherwise similar connection that fills correctly. The thermocouple-placement guide explains the distinction between measuring a joint and measuring nearby board surface.

Check flux access and contact before changing the alloy

Flux must reach the intended surfaces and retain suitable activity when solder arrives. Application, drying and preheat can influence that condition. A carrier opening, lead geometry or blocked nozzle may prevent consistent access. For a wave process, distinguish a joint that never contacted the wave from one that contacted it but did not wet adequately.

Map the defect by board position, conveyor orientation and fixture. Repeatable location patterns may indicate access or design constraints; lot-dependent patterns may point toward material or handling differences. The solder-skip investigation is the next step when missing contact is a credible explanation.

Preserve evidence of plating and surface condition

A soldering adjustment cannot repair an absent or damaged copper barrel. If cross-sections, wetting behavior or lot history suggest a bare-board issue, retain unassembled samples and fabrication identification. Compare the specified finish and storage history with the supplied material. Do the same for the component termination lot.

University of Maryland CALCE discusses poor hole fill and the role that barrel-plating defects can have in solderability. That supports investigating the board as well as the solder process; it does not imply every incomplete fill originates in fabrication. Use complementary evidence before assigning responsibility or deciding on rework.

Use the worksheet as a measurement aid

For a 1.00 mm finished hole, 0.60 mm round lead and 1.60 mm barrel height, the ideal annular cavity is approximately 0.804 cubic millimeters. If a documented section shows 1.20 mm of relevant filled height, the simple height ratio is 75 percent. These are example calculations, not an acceptance declaration for a particular product class.

Enter your own applicable minimum only when it is established by the responsible specification. The result should read as a margin to that entered value. It cannot verify circumferential wetting, metallurgical condition or hidden voids, and it does not override exceptions or measurement details in a controlled standard.

Close the issue at the correct level

Contain affected units, identify the process and material lots, and preserve representative evidence before repair alters the connection. Compare one well-defined change at a time where feasible. Recheck not only fill but bridging, component exposure and neighboring solder joints so an apparent improvement does not create a different defect.

When requesting 吃瓜tv review, include the hole and lead dimensions, assembly revision, marked location, process route, observed measurement and applicable acceptance requirement. A close-up without the board thickness or material history is rarely enough to distinguish geometry, heat and wetting. For the broader method choice, return to PCB soldering routes.

Review the barrel as a complete connection

Begin with finished dimensions rather than drill-tool nominal sizes. The lead shape, hole finish, board thickness and tolerances determine the available space. A square lead requires attention to its diagonal; a bent, plated or irregular termination may require a more detailed envelope than the simple worksheet supports.

Next, examine the thermal path and access. Large connected copper regions, component bodies, fixtures and the chosen soldering direction can change the response. Hole geometry alone cannot establish that flux and solder reach the intended surfaces or that sufficient wetting occurs throughout the connection.

Keep the measurement definition with any fill percentage. A vertical-height measure, an X-ray projection and a destructive section do not automatically supply identical information. The acceptance basis must identify what is being evaluated and how. An ideal annular volume is a geometric comparison, not an observed solder volume or a substitute for inspection.

If fill is inconsistent, preserve location and process patterns. Compare affected and unaffected joints by copper connection, lead and barrel geometry, orientation and position in the operation. Review plating and surface condition as well as heating and contact. A higher setting should not be the default answer to every incomplete connection.

Use the applicable controlled standard and contract to establish the acceptance requirements. The example threshold in a calculator is deliberately not presented as a universal IPC rule. Criteria can depend on the joint, class and agreed documents; an engineering disposition is separate from a numerical comparison.

For supplier review, provide the relevant fabrication and assembly drawings, finished-hole and lead requirements, joint locations, quantity and the intended inspection evidence. If a measurement comes from a failed sample, identify the method and preserve the sample where possible. This makes the discussion more useful than a general request for better hole fill.