2929 Bondply is an unreinforced thermoset bonding film for multilayer RF construction. It provides the adhesive dielectric between already patterned cores, so its flow, final thickness and electrical properties belong in the stackup model. Its role is different from a self-supporting copper-clad laminate.
Material system
Unreinforced thermoset bonding film
Technical properties
| Property | Reported value | Conditions / source |
|---|---|---|
| Process dielectric constant | 2.94 ± 0.05 | Typical; 10 GHz, 23°C, Z direction; IPC-TM-650 2.5.5.5.1. Source |
| Dissipation factor | 0.003 | Typical, 10 GHz, 23°C; IPC-TM-650 2.5.5.5; direction is not separately recorded here. Source |
| Thermal conductivity | 0.4 W/(m·K) | Typical; ASTM C518, 80°C; through-thickness thermal conduction. Source |
| CTE, X axis | 50 ppm/°C | Typical; 0°C to 150°C, IPC-TM-650 2.4.41; cured bondply. Source |
| CTE, Y axis | 50 ppm/°C | Typical; 0°C to 150°C, IPC-TM-650 2.4.41; cured bondply. Source |
| CTE, Z axis | 50 ppm/°C | Typical; 0°C to 150°C, IPC-TM-650 2.4.41; cured bondply. Source |
| Thermal coefficient of dielectric constant | -6 ppm/°C | Typical; -50°C to 150°C, IPC-TM-650 2.5.5.5 (modified temperature measurement); 10 GHz. Source |
| Water absorption | 0.1 % | Typical; D24/23, ASTM D570. Source |
Typical reported values are not a purchase specification. Process Dk, design Dk and values measured at different frequencies are not interchangeable.
Selection and design notes
- Consider it when a thin bonding layer and compatible thermoset process suit the chosen RF cores. Calculate the resin volume needed to fill etched copper topography rather than selecting plies only from a nominal dielectric-spacing target.
- If fields cross the bondline, include its dielectric constant and loss in the model. A thin adhesive may still influence stripline impedance or coupling when it occupies a meaningful fraction of the field region.
Thickness and copper options
The datasheet lists 1.5, 2.0 and 3.0 mil films with percentage tolerance; final bondline depends on flow and copper topography.
Bondply has no standard copper cladding of its own. Identify the surfaces and foil treatments it must bond.
Fabrication considerations
- Use the 2929 processing guidance for storage, handling and the actual press cycle. The selector's press-temperature entry is an orientation value, not a complete time, pressure and cooling recipe. Qualify fill and final thickness on the real copper pattern.
Application fit
- RF multilayer bonding
- Thin dielectric bondlines
- Hybrid microwave stackups
Limits and substitution checks
- Do not treat nominal film thickness as guaranteed finished dielectric spacing. Excess flow, incomplete fill and incompatible surface preparation can undermine a design even when the electrical table looks suitable. The unreinforced film also does not provide the same dimensional role as a glass-reinforced prepreg.