Frame-and-Fill Protection

Successful Chip-on-Board manufacturing relies on securely protected wire bonded connections.  There are several options for this protection that include conformal coating, glob top, and frame and fill (also commonly referred to as dam and fill).  Each offers its own advantages, but the frame and fill method provides the highest level of protection with processing consistency. Benefits include:

  •          Superior moisture/environmental resistance
  •          Increased mechanical strength to the PCB
  •          Ability to maintain specific coverage dimensions and weight
  •          High voltage isolation
  •          Fragile component stability
  •          Mechanical shock resistance
  •          Security of thick, opaque protective layer
  •          Cosmetic appeal- molded appearance
  •          No material migration under surrounding components
  •          Low viscosity fill material eliminates voids under wires
  •          Small particle size filler to permit flow through fine wire gaps
  •          High Tg materials for minimal movement

A stable "frame" is filled with low-viscosity fill material and results in a homogeneous protective coating of sensitive components

For optimal processing speed, the Structalit® series of frame and fill epoxies from Panacol can be dispensed wet-on-wet.  The higher viscosity frame, and the lower viscosity fill materials have been formulated to form a single, homogeneous protective coating when fully cured. These Structalit® epoxies are black in color and cure quickly with heat.  They are scratch and chemical resistant, do not bleed, and have high glass transition temperatures (Tg) for minimal movement.

Also available for frame and fill are a selection of Vitralit® UV curable epoxies from Panacol.  The Vitralit® epoxies are translucent materials and can be cured with UV light.  This permits very fast, in-line curing cycles, which increases production throughput.  The low temperatures of UV curing are ideally suited for use with temperature-sensitive PCB components.  These UV epoxies also contain thermal cure catalysts, that facilitate curing in areas shadowed from UV light, and areas where the applied epoxy layer is particularly thick.  With the exception of translucency, the physical properties of the Vitralit UV epoxies are similar to the Structalit® epoxies.  Both possess low ion content, (less than 20ppm), which makes them suitable for microelectronics packaging.

The following tables identify Panacol’s selection of frame and fill adhesives.  Additional products are also available for complete PCB assembly solutions.  If standard products do not fully meet required performance, Panacol-USA can provide customized adhesive options. Technical Data Sheets (TDS) can be downloaded by clicking on the adhesive name below.
 

Frame-and-Fill adhesives for semiconductor applications (< 20 ppm)

Adhesive Application Viscosity [mPas] Base Curing Properties
Structalit® 5704 Frame-material for Frame&Fill 60,000-100,000 epoxy thermal Black color
stable frame
suitable in combination with fills Structalit 5717-5722
No bleeding
Very low ion content (<10ppm)
High glass transition temperature
Structalit® 5717 Fill-material for Frame&Fill 3,000-8,000 epoxy thermal Very good flowability
High glass transition temperature
No bleeding
Very low ionic content (<10ppm)
Suitable for semiconductors
Structalit® 5719 Fill-material for Frame&Fill 7,000-11,000 epoxy thermal Very good flowability
High glass transition temperature
No bleeding
Very low ionic content (<10ppm)
Suitable for semiconductors
Structalit® 5720 Fill-material for Frame&Fill 10,000-15,000 epoxy thermal Very good flowability
High glass transition temperature
No bleeding
Very low ionic content (<10ppm)
suitable for semiconductors
Structalit® 5721 Fill-material for Frame&Fill 15,000-20,000 epoxy thermal Very good flowability
High glass transition temperature
No bleeding
Very low ionic content (<10ppm)
Suitable for semiconductors

Frame-and-Fill adhesives for electronics applications (< 900 ppm)

Adhesive Application Viscosity [mPas] Base Curing Properties
Structalit® 5891 T Frame-material for frame&fill 80,000-150,000 epoxy thermal Black color
stable frame material, can be applied wet-in-wet with filling material, suitable for frame stacking
stable edges
resistant to shocks
Structalit® 5791 Fill material for frame&fill 100,000-150,000 epoxy thermal
Structalit® 5893 Fill material for frame&fill 6,000-10,000 epoxy thermal Black color
excellent flow properties
filling material for frame&fill applications
high resistance to heat and chemicals
certified to ISO 10993-5 standards
Structalit® 5894 Glob top encapsulation
Encapsulation of electronic components
Bonding of electronic components
Fill material for frame&fill
45,000-55,000 epoxy thermal Black color
excellent flow properties
filling material for frame and fill applications on PCBs,
very high resistance to heat and chemicals

UV-curable Frame-and-Fill adhesives (< 20 ppm)

Adhesive Application Viscosity [mPas] Base Curing* Properties
Vitralit® 1671 Frame material for frame & fill applications 9,000-14,000 epoxy UV
secondary heat cure
Stable frame compound
high ion purity
electronic grade adhesive
high temperature conductivity
low water absorption
Vitralit® 1650 Fill for frame&fill 6,000-9,000 epoxy UV Electronic grade
low ion content
suitable for chip protection
Vitralit® 1657 Fill for frame&fill 5,000-15,000 epoxy UV Low ion content
excellent chemical resistance
low water absorption
suitable for covering open bonded chips
Vitralit® 1680 Fill for frame&fill 5,000-8,000 epoxy UV Very high resistance to heat and humidity
electronic grade adhesive
low ion content
suitable for chip protection
Vitralit® 1691 Fill for frame&fill 20,000-40,000 epoxy UV
secondary heat cure
black color
high ion purity
electronic grade adhesive
high temperature resistance
fast surface curing with UV light

*UV = 320 - 390 nm