Bonding materials join the layers or attach a circuit to a support, but their roles differ. A low-loss dielectric bondply, a thermoplastic bonding film and an electrically conductive attachment film cannot be treated as equivalent layers.

Identify what must be joined

For multilayer RF circuits, investigate the compatible prepreg or bondply alongside each core. Examples include RO4450F, RO4450T, 2929 bondply and SpeedWave 300P. Product inclusion here does not establish that every combination is supported.

Follow the electric and thermal fields

A bonding layer in a stripline structure contributes to its electrical response. A film beneath a ground plane may chiefly affect heat transfer and mechanical attachment. COOLSPAN TECA has a thermally and electrically conductive attachment role; it should not be substituted for an insulating dielectric solely because both are called adhesive films.

Specify the result of lamination

State the intended cured dielectric spacing and copper pattern, then ask the fabricator to select a supported resin-flow and press process. Include storage condition, handling life and subsequent assembly exposure in the review. The lamination guide explains why an unpressed sheet thickness does not by itself determine the spacing in a finished board.

References in this family

material2929 Bondply: Properties, Uses & Design Notes2929 Bondply is an unreinforced thermoset bonding film for multilayer RF construction.materialCuClad 6250 Bonding Film: Properties, Uses & Design NotesCuClad 6250 is a thermoplastic bonding film used to join PTFE microwave laminates.materialCuClad 6700 Bonding Film: Properties, Uses & Design NotesCuClad 6700 is a thermoplastic bonding film for PTFE microwave constructions, with a higher bonding-temperature regime than CuClad 6250.materialCOOLSPAN TECA: Properties, Uses & Design NotesCOOLSPAN TECA is a silver-filled epoxy adhesive film that forms a thermally and electrically conductive bond.materialRO4450F: Properties, Uses & Design NotesRO4450F is a ceramic-filled, glass-reinforced thermoset bonding material for RO4000 multilayers.materialRO4450T: Properties, Uses & Design NotesRO4450T is a spread-glass, ceramic-filled thermoset bonding material offered in several thin constructions.materialRO4460G2: Properties, Uses & Design NotesRO4460G2 is a higher-Dk ceramic-filled thermoset bonding material in the RO4400 group.materialRO1200 Bondply: Properties, Uses & Design NotesRO1200 Bondply is a ceramic-filled, non-glass-reinforced PTFE bonding material intended for multilayer constructions using the RO1200 laminate platform.materialSpeedWave 300P: Properties, Uses & Design NotesSpeedWave 300P is a low-Dk, glass-reinforced thermoset prepreg available in multiple glass styles and resin contents.materialRO3000 Series Bondply: Properties, Uses & Design NotesRO3000 Series Bondply is an undensified PTFE-based bonding form for homogeneous RO3000 multilayers.materialRO4450B Historical Reference: Properties, Uses & Design NotesRO4450B is retained as a historical reference because the official CU4000 foil compatibility document names it among RO4000 bonding materials.material3001 Bonding Film Historical Reference: Properties, Uses & Design Notes3001 Bonding Film is retained as a historical reference because official RT/duroid fabrication guidance discusses its use in bonding constructions.

Choose bonding by interface function, supported processing and final thickness, not by matching a core's Dk alone.

Technical sources

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