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Isola IS415 PCB: via geometry and multilayer construction
Connect IS415 material properties to board thickness, drill geometry, finished-hole requirements and a useful qualification plan.
Share your current requirements and open questions. Tool use is optional.
What is an Isola IS415 PCB?
An Isola IS415 PCB uses the specified IS415 epoxy laminate and prepreg system in a released board construction. For a demanding multilayer design, the material should be evaluated together with board thickness, plated holes, copper distribution and the expected thermal and electrical environment. A grade name cannot establish the manufacturability or reliability of every possible via structure.
The , revision D dated April 15, 2021, lists typical Tg of 200掳颁 by DSC and Td of 370掳颁 by TGA at 5% mass loss. Its 2 GHz Bereskin stripline entries are Dk 3.72 and Df 0.0120. Use the identified document and conditions rather than combining values from unrelated comparison tables.
| Material reference | Typical supplier value | Engineering use |
|---|---|---|
| Tg by DSC | 200掳颁 | Compare the same transition measurement |
| Td at 5% mass loss | 370掳颁 | Distinguish decomposition from operating limits |
| Dk / Df at 2 GHz | 3.72 / 0.0120 | Preserve the electrical test conditions |
| Z-axis CTE before / after Tg | 45 / 240 ppm/掳C | Inform construction review; not a via-life calculation |
This page focuses on the relationship between material, hole geometry and evidence. The Isola PCB material guide supports the earlier family-selection decision. If thermal terminology is the main uncertainty, review the high-Tg PCB guide before specifying a finished-board requirement.
Describe a plated hole with more than one diameter
The stated drill diameter and required finished-hole diameter serve different purposes. Plating and processing change the hole, and the fabrication plan must achieve the finished dimension and tolerance. Quoting one 鈥渁spect ratio鈥� without identifying its denominator makes two proposals difficult to compare and can hide different assumptions.
For a through-hole, board thickness divided by the stated drill diameter is one geometric ratio. Thickness divided by finished-hole diameter is another. Neither arithmetic result alone establishes a factory capability or predicts wall-copper distribution. For blind or buried structures, the relevant drilling and plating depth may differ from the full finished-board thickness, requiring a separate construction review.
State the finished-hole size, tolerance, plating requirement and intended function. A component lead, press-fit connection, thermal path or signal via can impose different constraints. Identify any special inspection or qualification evidence instead of expecting a single generic diameter note to communicate the whole requirement.
Compare drill, finished-hole and unused-barrel geometry
Enter total board thickness, the stated drill diameter, the required finished hole and an unused barrel length. The tool reports both thickness ratios, the radial dimensional difference and the unused fraction of the barrel. It rejects a finished-hole value that is not smaller than the stated drill diameter within this simplified comparison.
Isola IS415 PCB Engineering Planner
For a 4.0 mm board, a 0.40 mm stated drill and a 0.30 mm finished hole give ratios of 10 and approximately 13.33. The radial dimensional difference is 50 碌m. An unused barrel length of 1.20 mm represents 30% of the board thickness. Each number answers a different geometric question.
The 50 碌m difference is not a prediction of measured wall copper. Real hole preparation, tolerances and processing must be considered. The tool also does not establish a maximum acceptable aspect ratio, select a drill or calculate thermal fatigue. Use its output to remove ambiguity from an engineering inquiry, not to approve fabrication.
Review the hole inside the complete construction
The hole passes through a specific arrangement of cores, bonding regions and copper. That arrangement affects fabrication and thermal behaviour. Identify layer functions, dielectric intervals, copper thicknesses and the proposed core/prepreg construction before treating a via as an isolated cylinder.
| Review item | Information to provide | Reason it matters |
|---|---|---|
| Layer structure | Core/prepreg and pressed dielectric map | Defines the actual drilled and plated construction |
| Finished hole | Diameter, tolerance and functional requirement | Establishes the delivered dimensional target |
| Copper | Layer requirements and hole-wall evidence | Separates nominal input from accepted result |
| Thermal history | Assembly, rework and qualification exposure | Connects the structure to its intended mission |
Material expansion and copper constraint interact during thermal exposure. A higher Tg does not erase the effects of hole geometry, processing variation or repeated excursions. Review the thermal mission and qualification method for the actual board. The material table can inform that review but cannot replace it.
Use the multilayer PCB construction guide when the layer arrangement is still open. If blind, buried or sequentially formed interconnections are being considered, route that discussion through the HDI capability page. This IS415 tool does not model an HDI build or imply every hole architecture is available.
Treat an unused via barrel as an electrical question too
A signal that leaves a through-hole on an internal layer can leave unused barrel length. Its electrical effect depends on the complete transition, reference planes and signal requirements. The fraction reported by the tool is a geometry summary, not an insertion-loss or resonance prediction.
Identify the entry and exit layers, pad and antipad geometry, reference changes and any proposed stub-reduction method. A backdrilling proposal needs a controlled residual-stub requirement and manufacturing review. It should not be reduced to a percentage rule or assumed to be necessary for every high-speed route.
For controlled structures, use the PCB impedance design page to organize trace and coupon requirements. Via transitions can require more detailed electromagnetic or channel analysis than a uniform trace calculator provides. Agree which evidence is needed at prototype and production stages.
Match inspection evidence to the concern
A hole-geometry concern may call for specified dimensional inspection or microsection evidence. Electrical open/short testing answers a connectivity question. Thermal qualification evaluates behaviour under an agreed exposure. These records complement one another; none should be presented as a universal substitute for all the others.
Define the required records in the purchase and acceptance scope. Identify the drawing revision, sampling or test plan and any customer-specific reporting requirements. Ask how records will be associated with the delivered order. A generic image or sample report is useful for explanation but does not verify the actual boards being purchased.
The PCB electrical-testing page explains another part of this evidence chain. Passing a connectivity test does not establish a via's future fatigue life. Likewise, a sound microsection at one location does not describe every future operating condition of an assembled product.
Control changes between prototype and repeat production
A prototype and repeat order should share a controlled material and construction baseline. Record any changed core, prepreg, copper, drill plan or finished-hole requirement. If a sourcing issue prompts a material alternative, identify what mechanical, electrical and qualification checks must be revisited before approval.
Keep the material requirement specific enough for a useful quotation without replacing engineering review with a long list of unsupported limits. If a value comes from an old source, verify its document and test method. If the design requires a particular supplier recognition or test scope, confirm its applicability to the proposed construction and end use.
For a new product, define what the first build must teach you. It may be a geometry verification, a signal-transition comparison or a thermal qualification question. A focused first-article plan can be more useful than requesting every available test without explaining the acceptance decision each result supports.
What affects an IS415 manufacturing quotation?
Cost depends on the actual material construction, order quantity, panel utilization, drilling and plating work, finish and required evidence. Thick boards or demanding hole structures can change processing and verification requirements. The ratio calculator does not turn those requirements into a validated manufacturing price.
Isola IS415 PCB Budget Brief
The budget brief uses only the unit, setup and validation allowances you enter with a dated source and scope. Leave all cost fields blank when preparing a technical inquiry. There is no built-in market rate, generic FR-4 multiplier or stock-status claim. Geometry and cost inputs remain separate so a numerical hole result is not mistaken for price approval.
Send the released stackup, drill and finished-hole information, copper requirements, quantities and requested evidence through Contact. Highlight unresolved items, such as a proposed material alternative or residual stub. Engineering can then review a concrete construction instead of estimating from the material name alone.
IS415 via and material questions
Is IS415 simply a Tg200 operating-temperature board?
No. The cited 200掳颁 is a DSC transition value. Service temperature and reliability depend on the complete construction, components, environment and qualification requirements. Do not convert Tg into a continuous-use rating.
Which aspect-ratio value should I send to the manufacturer?
State the actual board thickness, drill assumption and finished-hole requirement, and identify the ratio definition. That is clearer than sending a single unexplained ratio. The fabricator must review the real drilling and plating construction.
Does the radial allowance equal deposited copper?
No. It is half the difference between two entered diameters. Processing effects, tolerances and measurement conditions are not modeled. Specify and verify hole-wall copper using the appropriate agreed evidence rather than inferring it from this arithmetic.
Does a 30% unused barrel require backdrilling?
Not by itself. Evaluate the actual electrical transition and system requirements. The tool reports geometry only; it does not model resonance or signal degradation. Any backdrilling requirement needs a controlled construction and manufacturing review.
Request IS415 PCB manufacturing review
Send the named laminate and prepreg, drawing revision, stackup, quantities and required evidence. Identify open material, construction or qualification questions so engineering can prepare a useful manufacturing proposal.
Attach a downloaded tool brief manually. Contact does not automatically receive these inputs. References reviewed September 2026. Illustrations use planning examples; photographs do not establish prices, delivery times or project-specific acceptance.