勛圖tv 繚 ENGINEERING GUIDE
Via Covering Types: Tenting, Plugging, Filling and Capping
Via covering is an umbrella term that can hide several different constructions. Tenting covers an opening with a film or mask; plugging places material into part of the hole; filling occupies the intended hole volume; capping adds a metal surface over a prepared filled structure. Select the construction from the required function and describe it explicitly in the fabrication data.
Use a cross-section to remove ambiguity
A top-down view may make a tented, plugged and capped opening look similarly closed. A section sketch shows where material is located, whether a cavity remains and whether the outer surface is metal or polymer. That distinction matters for solderability, planarity, cleaning and later thermal exposure.
IPC-4761 provides terminology for via protection. Refer to the applicable type and side designation, but also state the project requirements. The guide's classification does not by itself establish every dimensional or material acceptance condition for a particular board.
Match the treatment to the task
If the goal is a solderable pad above a via, investigate a complete filled and capped construction with the assembler. If the goal is surface coverage away from solder lands, another treatment may be appropriate. If test probing requires exposed copper, indiscriminate covering can make the board harder to test.
The selector below asks about surface function, solderability and the treated side. It suggests a construction to discuss and a missing specification question. It does not apply a blanket recommendation based only on hole diameter.
Compare the terms without collapsing them
Plugged vias focus on partial closure and cavity-related questions. Filled vias focus on the fill material and complete construction. Capped vias focus on the metal surface and pad condition. Copper-filled vias describe a particular conductive filling route. These pages are complementary; they are not interchangeable names for the same operation.
The word covered should also identify the covering material and location. A polymer cover over a fill is not the same as a copper cap. Where a drawing uses a historical shop abbreviation, attach a section or a precise process description to prevent a silent interpretation change.
Example: one board, three treatments
A board may have ordinary vias away from assembly pads, selected via-in-pad sites under a package, and exposed test connections. The appropriate treatment can differ across those regions. A single 'cover all vias' instruction can conflict with the test plan or omit the special work needed under the package.
Create a treatment map with unambiguous hole subsets. State how unlisted vias are handled and identify whether treatment applies to one side or both. Reconcile the map with mask data and any fill or cap layers in the release package.
Via-treatment decision brief
Via-treatment decision brief
Use the current inputs and keep the assumptions
Start with the example to understand the units and output, then use Clear for my inputs before entering your project. Example mode stays visibly labeled even if you edit its numbers. The form begins without a result so an illustrative value cannot be mistaken for an approved requirement. Every field must have a valid value; zero is accepted only where it has a meaningful role in the particular model.
Read the input notes before calculating. They identify the physical boundary and what is excluded. Keep the same unit convention across the drawing and worksheet. Changing an input invalidates the previous result and disables its download until you calculate again. This prevents an old number from appearing to describe a revised geometry.
The result is a screening record. A negative margin or an out-of-range condition identifies a question to resolve; a positive margin is not a manufacturing approval. Use the record with the actual drawing, material and project requirement. The model does not load CAD files, inspect images or retrieve private factory data.
Download the current result if it helps the discussion. The text includes the entered inputs, result and limitations. It stays on your device until you choose to attach or share it. Contact is a separate step; this page does not automatically populate the enquiry form or upload a file. Avoid confidential identifiers if you only need an exploratory calculation.
| Input | What to establish before using it |
|---|---|
| Review reference | Use a nonconfidential reference that lets you connect this calculation to the correct drawing revision. |
| Primary task | Choose the finished function. The same nominal hole can need a different treatment when it moves into a component land. |
| Side or coverage to discuss | This is a specification question, not a command to apply the same process to every hole. Identify the actual treated subset in the drawing. |
| Hole subset or unresolved requirement | Use a short nonconfidential description. This text stays in the browser and will appear in the optional downloaded record. |
Inspection follows the construction
Surface coverage, fill completeness, cap condition and internal copper integrity require different observations. Ask what can be established by optical inspection and what needs a section, electrical test or other agreed evidence. A closed-looking surface is not a universal acceptance result.
When changes are proposed, assess their effect on assembly, coating, cleaning and test access. Do not approve a cheaper treatment as equivalent until its functional consequences are understood. Keep accepted substitutions with the drawing revision.
Make the quotation comparable
Provide hole sizes, layer spans, count or identified subset, material requirements, surface function and acceptance conditions. Ask for filling, planarization, capping and inspection to be stated where included. Price comparisons become misleading if one offer includes only a mask treatment and another includes a metallized cap.
Is every via protection type necessary on every board? No. Can the same CAD mask layer define every treatment? Usually additional construction information is needed. Does a named IPC type certify the board? No. Use the classification to communicate a design, then agree a measurable manufacturing proposal and an inspection scope appropriate to the product.
Specify the via treatment by function and cross-section
Build a treatment map that can be read without guessing from a solder-mask image. Identify the affected hole subset, the treated side or internal location, the material and the required finished surface. A small section sketch can show whether material bridges an opening, enters part of the barrel, fills a cavity or supports a metal cap. That sketch should agree with the written note and the released layer data.
Review the downstream assembly task. A pad under a component, an exposed test location and a via away from solderable copper may need different surface conditions. Keep stencil, cleaning, coating and test-access needs in the discussion where relevant. A treatment that solves one soldering concern can create another problem if it blocks a required probe point or leaves an unsuitable surface under a package.
Material selection also needs a process owner. A named fill or mask family does not establish that every variant has the same handling, cure or performance. Use the manufacturer's current product information through the qualified fabrication process. Avoid combining isolated parameters from unrelated technical sheets into a new recipe. The customer drawing should define the required construction and acceptance conditions, while the manufacturer controls the applicable production method.
Decide how the result will be assessed. Surface appearance can establish some coverage conditions; internal fill and copper structure may need other evidence. Identify whether a concern is a visible opening, a cavity, a void, a recess, a protrusion or an electrical connection. These are different characteristics. Agree the measurement location, sample representation and disposition of nonconforming results rather than using 'closed via' as a universal pass criterion.
When a quotation proposes an alternative, compare the complete finished structure. A tent is not automatically equivalent to a plug, and a polymer fill is not automatically equivalent to deposited copper. Cost and lead time should be considered after the functional differences are understood. Keep any accepted substitution in the controlled release record so later lots do not drift between interpretations.
For an early enquiry, provide the hole map, one enlarged view of the difficult assembly region and the intended function. The treatment selector is a conversation aid. It does not select an IPC acceptance class, prove a fill process or certify a solderable land. A useful review ends with an explicit cross-section and a clear definition of what evidence will demonstrate the required result.
Standards, source context and limits
Use the performance and acceptance documents named in the procurement agreement, including their revisions and any applicable addenda. A design guide explains choices; a product acceptance requirement defines what must be demonstrated. Neither a reference link nor a calculator result is a certification of the board or the supplier. Where a value is contractually important, check the controlled document and agree the measurement method with the responsible parties.
Examples on this page are deliberately labeled and are not advertised 勛圖tv limits. Supplier documentation is linked for the specific material or process context it explains. Equipment photographs and cross-section examples show the subject; they are not current production, inspection or qualification records for your order.