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Specify the TerraGreen variant before the board

An Isola TerraGreen PCB is not a complete material specification until the exact TerraGreen designation and construction are recorded. TerraGreen, TerraGreen RF/MW, TerraGreen 400G, 400GE and 400G2 must not be treated as alternate spellings. A search for the family name often combines three jobs: understanding its electrical properties, deciding whether a variant fits a channel, and obtaining a fabrication quotation. This page connects those jobs without collapsing their evidence into one generic table.

Begin with the laminate name written on the engineering drawing. If it says only TerraGreen, resolve the intended grade before comparing prices. Describe the frequency or channel requirement, the proposed stackup and the allowed substitution policy. You can request a material and fabrication review with these open questions clearly marked; using the calculator first is optional.

A traceable reference for the unsuffixed material

The checked for this guide has a January 4, 2024 footer. It reports typical Dk 3.44 at 2, 5 and 10 GHz using IPC-TM-650 2.5.5.5. The corresponding Bereskin-stripline Df values are 0.0033, 0.0032 and 0.0032. It also reports Tg 200掳C by DSC. These figures refer to the unsuffixed document, not the entire TerraGreen family.

The document footer identifies revision E while its revision notes include an F entry. Preserve the dated document and resolve that discrepancy with the material source when specifying acceptance data. A website headline, a saved catalogue and a construction table may have different revision histories. That is a reason to keep the source with the design record, not a reason to select whichever number looks most favorable.

Family identity and electrical comparison are separate checks

The manufacturer's and provide distinct product records. Their existence does not settle procurement availability for your thickness and foil, and it does not authorize moving between variants. Keep the exact designation in the RFQ and ask for construction-specific evidence. Compare values only after their measurement conditions are understood.

At a minimum, match frequency, method, conditioning and the relevant construction description. If one source provides a product-summary Dk and another gives an extracted design Dk, do not calculate a percentage improvement as though they were the same measurement. If a condition is missing, state it as unresolved. An honest incomplete comparison is more useful than a precise-looking result built from incompatible records.

Compare dielectric-loss scenarios on a common basis

The worksheet isolates the dielectric contribution of a uniform, low-loss, homogeneous TEM transmission line. It asks for both permittivity and loss tangent at a common frequency. Its comparison is deliberately withheld when the data conditions differ or remain unresolved. It is not a microstrip field solver, a laminate recommender or a high-speed channel simulator.

The example uses the unsuffixed material's 10 GHz reference values for scenario A and an explicitly hypothetical lower loss tangent for scenario B. Scenario B is not a named TerraGreen product. Change only one input at a time to understand sensitivity, then replace the example with your documented construction data. Never read the lower calculated dielectric term as a total board-loss or bit-error-rate guarantee.

Separate dielectric loss from the complete channel

In the worksheet, dielectric attenuation is approximated by 8.686 脳 蟺 脳 frequency 脳 length 脳 square root of relative permittivity 脳 loss tangent, divided by the speed of light. Use SI units inside the expression; the interface converts GHz and millimeters. A 100 mm line at 10 GHz with relative permittivity 3.44 and loss tangent 0.0032 gives approximately 0.540 dB of dielectric-only attenuation. Halving its uniform length halves this modeled term.

That calculation omits conductor skin effect, copper roughness, plating, bends, vias, launches, return loss and radiation. It also assumes a suitable low-loss TEM model. A measured connector-to-connector channel can therefore have substantially different insertion loss. Use PCB impedance planning for the geometry discussion and bring the actual channel model to the fabrication review. A good material decision includes the signal path that the system will really use.

Build a stackup that preserves the comparison

Suppose two candidate constructions use different glass styles, foil profiles or pressed dielectric thicknesses. Their electrical differences cannot be assigned to the resin system alone. Ask for a layer-by-layer proposal showing those changes before comparing fabrication cost. Record the finished conductor definition, not just the starting copper weight, and identify solder-mask coverage on critical outer-layer traces.

A hybrid board can place a lower-loss construction where it serves a defined path while using another approved construction elsewhere. The engineering review must still address bonding compatibility, dimensional movement and the transition between reference structures. The economic benefit cannot be inferred from the area of expensive material alone; process complexity, material purchasing increments and verification can change the result.

For a repeat order, preserve the construction and the measurement basis together. A substitution approval should describe which data were reviewed, which parts of the stack changed and which validation remains necessary. Do not use a family name as the change record. If a supplier proposes a different suffix or copper treatment, ask for the difference in writing before accepting a nominally identical quotation.

Halogen-free is one requirement, not a complete approval

Environmental declarations, material electrical measurements and finished-board acceptance answer different questions. Request declarations for the exact material designation and revision needed by your product program. Do not infer whole-product compliance from a material data-sheet badge. Components, finishes, assembly processes and the product's regulatory scope may introduce separate requirements.

A practical evidence plan might include a material identity record, the approved fabrication stack, dimensional inspection, connectivity testing and a specifically defined impedance or RF coupon. The required selection depends on the design and purchase specification. State the specimen, measurement method and acceptance source instead of asking for an undefined premium inspection package. That allows a supplier to quote the actual work and the receiving team to interpret the results.

Decide by the channel and manufacturing problem

For a digital backplane, the critical review may concern long routes, connector interfaces, reference continuity and the complete channel budget. For a mixed-signal RF board, the important questions may instead include phase, launch geometry and the copper profile on shorter critical paths. The family label does not choose between these priorities. Describe the operating band, route structure and measurement planes so the discussion reaches the actual engineering constraint.

If the project is still comparing brands, start with the Isola material family guide and then narrow the choice to a documented construction. If I-Tera MT40 is a candidate, its fabrication and stackup page addresses the material-to-board handoff. These are alternative review paths, not assertions that the materials are equivalent. The eventual quotation should refer to the selected, approved construction.

Budget the exact variant and verification scope

Two TerraGreen quotations can differ because they contain different suffixes, glass, foil, panel utilization or test deliverables. Align those items before comparing the unit prices. Board positions per production panel should already account for tooling margins and coupons; the tool does not calculate nesting. Expected usable fraction is a planning assumption, not the probability of delivering the order on time.

All allowances are entered by you. The model adds whole-panel manufacturing allowances, separately identified board extras, one-time setup and one-time verification. It is an uncalibrated planning estimate, not a current material price list. Enter the exact variant in the source field. Avoid charging again for foil, drilling or inspection already included in a supplied panel allowance. Tax, shipping and assembly require an explicitly stated scope.

For the final request, include the fabrication data, stackup, quantity, intended date and documents defining the critical electrical requirements. The PCB Manufacturing service route provides the broader procurement context. A downloaded worksheet is an optional attachment; it does not automatically populate Contact or upload project files.

Common TerraGreen specification questions