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What is an Isola 370HR PCB?

An Isola 370HR PCB uses the 370HR epoxy laminate and prepreg system in a specified circuit-board construction. It is a material choice within a finished multilayer design, not a standalone guarantee of reliability. The grade, layer structure, drilled holes, copper, fabrication process and thermal exposure must be considered together.

The identifies typical Tg of 180掳颁 by DSC and Td of 340掳颁 by TGA at 5% mass loss. It also reports Z-axis CTE values of 45 ppm/掳C below Tg and 230 ppm/掳C above Tg. These are supplier material data, not 吃瓜tv acceptance limits or a continuous operating-temperature rating.

This page focuses on translating thermal-material information into a useful manufacturing review. The Isola material selector covers the family-level choice. If the actual bottleneck is signal attenuation on a long route, compare the electrical requirements before assuming that a thermally robust grade solves the channel problem.

Why Z-axis expansion matters around plated holes

A board expands differently through its thickness and along its plane. A plated through-hole is mechanically coupled to the material around it, so the relevant reliability question involves geometry and constraint as well as material expansion. Thicker boards, hole diameter, wall-copper distribution and the complete thermal history all belong in the review.

The transition in resin response makes a single constant-CTE assumption particularly incomplete when a thermal excursion crosses Tg. That does not mean crossing Tg causes immediate failure. It means the material's response changes and the actual structure must be qualified for the intended exposure. A simple calculation can illustrate sensitivity, while a test plan establishes evidence for the construction.

Separate material screening from finished-board acceptance. A microsection can document geometry, but a single image does not establish fatigue life. A connectivity test identifies opens and shorts under its test conditions, but it does not prove every interconnection survives the future environment. The appropriate evidence depends on the customer's product requirements and agreed qualification method.

Explore two-slope Z-expansion sensitivity

Enter starting thickness, the temperature interval, an assumed transition and constant CTE values on either side. The tool integrates those two temperature intervals and reports free thickness change. It illustrates sensitivity to board thickness and temperature range; it does not model duration, plated-hole stress or fatigue.

For the illustrative 1.60 mm board, heating from 20掳C to 240掳C with a transition at 180掳颁 divides the interval into 160掳C below and 60掳C above. Using 45 and 230 ppm/掳C gives a simplified free thickness change of 33.6 碌m, or 2.10%. Increasing starting board thickness doubles the absolute expansion if all other model inputs remain unchanged.

This result is not a reproduction of the supplier's measured total-expansion value. Real TMA response is not exactly two straight lines, and the temperature range, moisture and material state matter. Do not replace a datasheet measurement with this arithmetic or use the calculated expansion as an acceptance criterion. Carry the actual material and test references into the engineering review.

Specify the construction that will use 370HR

Identify which layers are signal, reference or power and which dielectric intervals control impedance. Define the copper requirement separately for inner and outer layers. Record the core and prepreg descriptions, glass style, resin content and proposed pressed thickness. These details determine what the manufacturer must source and build; 鈥�370HR, six layers鈥� leaves too much unresolved.

A symmetric layer count is not a complete balance check. Copper coverage can differ between opposite layers, and dense copper regions change local processing conditions. Review the artwork together with the stackup. Where thickness is critical to connectors or an enclosure, state the reference faces and tolerance instead of relying on a generic nominal board thickness.

The multilayer construction guide is the next step when layer assignments or core/prepreg planning are still open. The 370HR selection should become part of that controlled construction. It should not float independently in a purchase order while the actual fabrication drawing still calls out a different generic material.

Check the signal task separately from thermal performance

Thermal robustness and low electrical loss are different properties. Define the relevant signal frequencies, route lengths and loss or timing requirements. Keep the chosen material data associated with its test method and frequency. A headline dielectric number used for product comparison may not describe the particular glass/resin construction used for a controlled-impedance layer.

For a short control route, geometry and reference continuity may dominate the immediate layout review. For a longer high-speed route, loss and transitions may justify a more detailed material comparison. The FR408HR loss-budget page serves that separate task. Moving there does not imply FR408HR is a drop-in replacement for an already qualified 370HR build.

If impedance is specified, include the structure type, layer, target, tolerance and coupon requirements. The fabricator needs permission boundaries for any trace adjustment. A TDR result is useful evidence for the agreed structure, but it should be traceable to the correct revision and coupon. Avoid accepting a generic report that cannot be matched to the delivered construction.

Include the complete thermal history in the review

List lamination cycles, assembly passes, possible selective soldering and planned rework. A board exposed to multiple processes may experience a different history from the single-step example used in an early material discussion. Identify where profiles are known and where engineering still needs to measure or define them.

Storage and moisture handling are also process inputs. Use the relevant material and assembly guidance for the actual construction; do not prescribe one bake temperature for every board, finish or component condition. If a board has been stored or exposed beyond the expected interval, have the responsible process team establish a suitable handling decision.

For a repeat design, compare the new build with the approved one: same core/prepreg, foil, layer thicknesses, holes and acceptance plan. Any change should be documented before production. A material availability issue is a legitimate reason to propose an alternative, but it is not permission to keep the old material name on a different build.

Ask for evidence that matches the design question

The PCB quality-control page explains how manufacturing checks fit into a control plan. Agree the records needed for your order rather than assuming every possible test is included in a standard price. A useful inquiry names both the required result and how it will be verified.

Prepare a 370HR manufacturing and budget brief

The cost depends on the actual material purchase and construction, not simply the 180掳颁 Tg headline. Layer count, sheet utilization, copper, pressing stages, hole complexity, finish, coupons and documentation can change the quotation. Unusual material combinations may introduce procurement constraints even when the finished board area is small.

Leave prices blank to produce a technical RFQ brief. When you have a suitable quotation or allowance, record its source, date and scope before adding the unit, setup and validation amounts. The tool performs transparent arithmetic; it does not supply current factory rates or apply a generic FR-4 cost factor to 370HR.

Compare alternatives using the same quantities and evidence requirements. A proposal that omits qualification coupons is not automatically a like-for-like cheaper option. If the material or stackup changes, request a revised cost basis and technical review. The brief can be downloaded and manually attached to a direct inquiry without requiring an account.

370HR design and purchasing questions