Engineering resources

What an Arlon PCB specification must contain

A useful Arlon PCB specification turns a material name into a build that two engineers can interpret the same way. It identifies the laminate and bonding system, defines the finished construction, and states how the board will be accepted. Writing only “Arlon, high temperature” leaves too many decisions open for a comparable quotation or a controlled manufacturing release.

Use the material library to identify candidate grades, then assemble the following requirements into one revision-controlled fabrication package.

1. Identify the material and its role in the stack

State the manufacturer, exact grade and whether the material is a copper-clad core, bonding prepreg or another layer. An Arlon EMD polyimide grade and a low-flow bonding prepreg do different jobs. For example, the manufacturer identifies 85N as a polyimide laminate/prepreg system, while its controlled-flow guidance describes products intended to limit resin movement around rigid-flex boundaries and heat-sink cutouts. A shared brand name does not make them interchangeable.

Record the data-sheet title, revision when available, and retrieval date. If the document lacks a visible revision, record that fact and retain the exact file used for approval. State whether substitutions require written approval. “Equivalent permitted” should be accompanied by a review procedure and the properties the substitute must satisfy.

2. Define the finished construction

Provide a layer-by-layer drawing showing copper layers, dielectric layers, reference planes, core thicknesses and intended bonding locations. Distinguish starting copper from finished copper and starting prepreg thickness from the required cured dielectric thickness. Put tolerances next to finished dimensions rather than assuming a nominal value is an acceptance limit.

Include the board outline, finished thickness, plated and nonplated hole definitions, slot dimensions and any controlled depths. Identify which file governs if the drawing and fabrication data disagree. For rigid-flex work, show the rigid boundary, bend region and restrictions on resin intrusion. Review that geometry against the chosen bonding material instead of specifying “no-flow” as an absolute promise of zero resin movement.

3. Separate operating requirements from material properties

Describe the intended temperature range, time at temperature, thermal cycling, moisture exposure and assembly sequence as design inputs. Avoid treating a glass-transition value as an approved continuous operating temperature. Require the engineering review to address the assembled construction and its intended environment.

When a property drives selection, name its test method, conditions and acceptance basis. A typical data-sheet value is useful for screening; decide explicitly whether purchasing needs a guaranteed limit, a lot certificate, an agreed qualification result or simply identification of the specified grade. Do not turn every brochure value into an acceptance requirement without checking how it can be measured.

4. Make electrical and surface requirements measurable

For controlled impedance, identify each net class, its target and tolerance, signal layer, reference plane, and the test or coupon arrangement to be agreed. Ask for the proposed stack-up before final approval. A dielectric constant by itself cannot define a finished trace geometry.

Name the surface finish and the areas to which it applies. Gold-plated contacts and solderable pads may have different requirements. Specify the applicable finish standard or project specification, thickness acceptance criteria and measurement locations. If converting units, 1 microinch equals 0.0254 micrometre; a conversion does not establish the correct finish thickness for the application. The gold-thickness tool helps check units before review.

5. Agree on evidence and acceptance

List the required inspection, electrical test, dimensional reports, traceability and packaging. Name any applicable standard with its revision and agreed class where relevant. A laminate’s stated conformance must not be presented as certification of the finished board or the fabricator. Resolve conflicts among the purchase order, drawing and referenced standards before releasing the job.

Worked example: closing an incomplete specification

Hypothetical planning example, not a qualified stack-up or a manufacturing offer. A team requests an eight-layer instrumentation board with the note “Arlon polyimide, 1.6 mm, gold finish.” The table shows what must be resolved before this note becomes a release package.

The example deliberately leaves tolerances and process settings undecided. Inventing them would hide the work still required. A clear open-item list is more useful than a complete-looking drawing built from unapproved assumptions.

A final release checklist

• The drawing, stack-up and fabrication data carry matching part and revision identifiers.
• Every material has an exact designation, assigned role and substitution rule.
• Finished dimensions, copper requirements, holes and surface finishes have agreed acceptance criteria.
• Electrical and environmental requirements are explicit, with unresolved items identified.
• The inspection plan states what evidence accompanies the boards.
• The fabricator has acknowledged the final package and its exceptions.

For the next step, review the manufacturing handoff process or submit your stack-up, fabrication files and open questions for an engineering review. Material availability, suitability and quotation terms require project-specific confirmation.

Manufacturer references

Consulted 8 October 2026. No document revision was visible in the retrieved web-page extracts. The checklist and hypothetical example above are original editorial guidance, not a manufacturer-approved fabrication procedure.

• Arlon EMD: 85N product information — material identity and laminate/prepreg context.
• Arlon EMD: controlled-flow prepreg applications — bonding roles and controlled resin movement.