Frame&Fill Adhesives
Frame-and-fill processes are used to protect highly sensitive areas or sensitive information on electronic circuit boards. In the first step, a high-viscosity barrier – the so-called frame – is applied. In the next step, this area is filled with low-viscosity filler material – the fill. Frame and fill offers two primary advantages: Barrier and potting (fill) heights can be kept to a minimum, and the frame and fill combine to form a homogeneous protective coating. With this precise process, specific areas on the PCB can be protected from mechanical and environmental impact factors.
Structalit® frame&fill adhesives from Hoenle are formulated to be completely compatible with each other. Both materials can be optimally dispensed wet-on-wet. The highly thixotropic frame prevents the lower viscosity fill from migrating into undesired areas on the PCB. The frame and fill are then cured in a single step.
Structalit® brand frame&fill adhesives are black, one-component epoxy resin adhesives that cure thermally. They have a high glass transition temperature, are extremely scratch and chemical resistant, and do not bleed.
Hoenle also offers Vitralit® brand adhesives, which are translucent, UV-curing epoxy-based frame&fill materials. These UV-curable adhesives can likewise be dispensed wet-on-wet and then cured in seconds under UV or UV LED light. These UV epoxy resins are equally robust against temperature and environmental influences. Some of these UV-curable adhesives can be thermally post-cured to ensure that the adhesive also polymerizes reliably in shadowed areas or when applied in thicker layers. The advantage of UV-curable frame&fills is their fast curing at low temperature. Rigid and flexible circuit boards containing temperature-sensitive components can be processed in-line, in a continuous production flow.
Hoenle offers frame&fill adhesives with a low ion content with less than 20 ppm, making them particularly suitable for chip encapsulation on electronic circuit boards.
In the following tables you will find a selection of Hoenle adhesives suitable for Frame&Fill applications. Other products or customized solutions are available on request. Technical data sheets can be downloaded by clicking on the adhesive name.
| Adhesive | Application Areas | Viscosity [mPas] | Base | Curing * | Special Properties |
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60,000-100,000 (Rheometer, 25 °C, 10s^-1) | epoxy | thermal |
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3,000-8,000 (Rheometer, 25°C, 10s^-1) | epoxy | thermal |
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7,000-11,000 (Rheometer, 25°C, 5s^-1) | epoxy | thermal |
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10,000-15,000 (Rheometer, 25°C, 5s^-1) | epoxy | thermal |
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80,000-150,000 (Rheometer, 25 °C, 10s^-1 ) | epoxy | thermal |
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45,000-65,000 | epoxy | thermal |
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6,000-10,000 (Rheometer, 25°C, 10s^-1) | epoxy | thermal |
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20,000-30,000 (Rheometer, 25 °C, 20s ^-1) | epoxy | thermal |
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9,000-14,000 (Rheometer, 10s^-1) | epoxy | UV secondary heat cure |
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3,000-5,000 | epoxy | UV |
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20,000-40,000 | epoxy | UV secondary heat cure |
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*UV = 320 – 390 nm VIS = 405 nm
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