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Specify Arlon 85N as a rigid polyimide construction

An Arlon 85N PCB is a rigid board manufactured with the specified 85N polyimide laminate and approved prepreg construction. It is not an Arlon PTFE RF laminate, a generic flexible polyimide film, or a finished-board operating-temperature rating. Engineers investigating this material usually need to connect thermal exposure, multilayer geometry and plated-hole reliability with a fabrication process that can be reviewed and documented.

The identifies a pure polyimide system for high-temperature applications. The useful procurement question is which exact construction and evidence support your board. Send the drawing, layer assignment, copper and hole requirements, assembly history and intended use conditions for a material-specific fabrication review. The calculators are optional aids to that discussion.

Keep thermal properties tied to their test interval

The , carrying a 2025 revision mark, lists Tg at least 250°C and total Z-axis expansion of 1.2% between 50°C and 260°C. It identifies IPC-4101 /40 and /41 in its material description. These statements refer to the material documentation; they do not certify a ³Ô¹Ïtv production process or establish a product's continuous operating limit.

The expansion figure is especially useful when its scope remains visible. It is an integrated change across a fixed temperature interval. It is not a complete expansion curve, a constant CTE applicable at every temperature, or the strain in a plated copper barrel. Keep the source interval with the value and avoid converting it into an arbitrary reflow-cycle count or reliability lifetime.

Fixed-interval free expansion worksheet

Enter a starting free dielectric thickness referenced to 50°C. The tool applies the published 1.2% interval change and shows the illustrative thickness increase at 260°C. It intentionally does not offer a temperature slider: the cited total expansion cannot justify a complete temperature-dependent curve. The required source field records the construction and assumptions associated with the calculation.

For an illustrative 2.00 mm free dielectric thickness, 1.2% corresponds to 0.024 mm, or 24 µm, of expansion. The calculated ending thickness is 2.024 mm. Doubling the starting thickness doubles this free-expansion amount. This simple proportionality helps communicate scale; it does not describe the actual movement of a copper-constrained, heterogeneous multilayer assembly.

Why free expansion is not plated-hole strain

A plated through hole interacts with the surrounding laminate, internal lands and surface structures. Copper and dielectric do not move independently in the finished board. Local adhesion, resin behavior, glass reinforcement, hole geometry, deposited copper and thermal history all influence the response. Taking the worksheet's thickness change and dividing it by barrel length would not establish a validated fatigue or failure prediction.

For a meaningful reliability discussion, describe the board thickness, hole spans, prepared drill and finished bore separately. Identify critical populations rather than assuming every hole is represented by the smallest nominal drill. Ask which specimens and conditioning will represent the proposed construction. Define the measured feature and acceptance source so the resulting evidence can be interpreted consistently by the designer, fabricator and receiving team.

A material with favorable free-expansion behavior does not remove the need for this review. Conversely, a tool that reports a larger absolute expansion for a thicker specimen has not proven that specimen will fail. The calculation is an explanatory input, not a pass/fail classifier. The actual construction and the qualification question must determine the next engineering step.

Organize the multilayer stack and material records

Separate dielectric-only core dimensions, complete pressed bondlines and finished copper contributions in the drawing. State the glass and resin requirements or identify the approved supplier construction. Raw prepreg thickness is not a universal pressed bondline thickness. Copper distribution and local resin demand can affect the construction review, so include copper-heavy regions, large clearances and unusual mechanical features early.

Symmetry is useful as a design consideration, but a symmetric list of nominal thicknesses is not evidence of flatness or stress control. Plane coverage, local geometry and processing history can differ across the board. Keep the electrical layer functions and physical construction on the same revision so an adjustment made for fabrication does not silently change a reference path or impedance requirement.

The multilayer PCB guide provides broader layer-planning context. If electrical geometry is critical, also review the PCB impedance requirements with data suitable for the intended frequency and construction. Do not extrapolate a low-frequency dielectric property into a high-speed model simply because thermal performance drove the original material selection.

Control the material condition through processing

Arlon publishes process guidance linked from its official product page. Treat that guidance as a starting basis for a qualified production process, not a universal set of temperatures and times to copy into every order. The correct production settings depend on the actual material state, panel, copper pattern and equipment. Ask the supplier to describe how the selected process supports the finished-board requirements.

Moisture handling needs a defined procedure through storage, fabrication and assembly. Record packaging and exposure history, the material condition and the applicable process owner. Before calling for a bake, consider whether the item is prepreg, laminate, a finished bare board or an assembled board with components and finishes. Those states do not automatically share one permissible thermal treatment.

The offers background for discussing this issue. A product-specific handling decision still needs the controlled source and the actual construction. Avoid treating a material name as permission for an improvised bake cycle, or treating a dry-looking surface as proof of internal material condition.

Agree the evidence before buying the boards

An acceptance plan can include material identity, dimensional inspection, connectivity testing, cross-sections and a defined thermal qualification program. The appropriate combination depends on the project. List the specimen, sample scope, conditioning, procedure and acceptance criterion for each requested result. A generic request for high reliability is difficult to quote and does not tell the receiving team what evidence to expect.

Successful electrical continuity testing does not by itself establish thermal fatigue life. A material certificate identifies a supply record but does not prove every finished feature. A qualification specimen can support a particular construction and process, while routine lot inspection supplies a different kind of evidence. Keep the responsibilities and records distinct so the final release decision is based on the intended scope.

For long-running programs, define the change-notification requirements. A revised material construction, foil, drilling approach or fabrication site may require review even if the board's commercial description remains unchanged. Ask how changes will be identified and which records will be available for a repeat order. This is often more useful than asking for a broad maximum-temperature claim.

When to review 85N against 85HP

If the engineering concern includes local resin behavior, dense plated holes or a dielectric thermal path, Arlon 85HP is a separate filled-polyimide construction to investigate. Compare the actual requirements, data conditions and fabrication proposal. Do not assume equal Tg means equal behavior, and do not transfer a thermal-conductivity or expansion figure from one material page to the other.

The Arlon family guide also includes RF-oriented materials, which serve different tasks. Keep the resin system and exact grade visible when navigating that family. A board intended for a demanding thermal environment may still have RF requirements, but those requirements need their own material data and electrical evidence; the brand alone does not solve both problems.

Plan the lot with a defined polyimide scope

85N PCB cost depends on the exact construction, material purchasing increments, panel utilization, process complexity, tooling and inspection scope. A first qualification lot may include engineering and thermal/hole evidence that a routine repeat lot does not. Separate those one-time items from recurring fabrication allowances before comparing unit prices.

The worksheet rounds up to whole production panels using an entered position count and expected usable fraction. Neither input is a nesting result or a guaranteed yield. All prices are user-supplied; the tool includes no FR-4 rates or invented polyimide multiplier. Its output is an uncalibrated planning estimate. Avoid double counting work included in the panel allowance, and state whether freight, tax, assembly and special testing are excluded.

Use PCB Manufacturing for the broader service route, then send the actual drawing, stack, quantity, desired date and acceptance scope. The local brief is an optional attachment. No files or parameters are transferred automatically into Contact, and an email draft is not a submitted enquiry.

Arlon 85N questions before release