Edge Bonding Implementation

Versal ACAP Packaging and Pinouts Architecture Manual (AM013)

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Edge bonding is the dispensing of an epoxy material around the periphery of the package after board mount. Xilinx requires the use of the Zymet UA-2605-B edge-bonding material. Edge bonding is not intended to under fill the package or contact the solder balls. This technique allows for component rework and improves the robustness of the mounted component by controlling the expansion and warpage of the board during normal operating conditions To place the adhesive while using an in-line soldering robot, Xilinx recommends the parameters shown in the following table.
Table 1. Process Parameters for Edge Bonding
Process Parameter Range Specification
Needle size

Range: 25 - 18 gauge

Recommended: 18 gauge

Needle height

Range: Above the device edge midpoint, or 0 to 1.5 mm below the top surface of the device

Recommended: 1.0 mm below the top surface of the device

Needle edge spacing

Range: Half to three quarters of needle outer diameter (D)

Recommended: Half of needle diameter (D/2), approximately 1.0 mm

Dispense needle speed

Range: 0.1 to 200 mm/second

Recommended: 9 mm/second

Value pressure

Range: 20 to 60 psi

Recommended: 1.2 kgf/cm² @17 psi

The adhesive is dispensed along the perimeter of the assembled component at a width of 3 mm and a height of 50% to 90% the substrate height, leaving a small section at the center of each edge unbonded, as illustrated in the following figure. This is to ensure that there is an outlet for any expansion of the air during processing. Xilinx recommends centering the opening on each side with a width of 25–30% the length of the package substrate. The exact locations and size of the openings can be varied depending on the design and rework.

Figure 1. Edge Bonding Adhesive Placement Parameters
Recommended: Curing conditions are 155°C for 10 minutes.

Component Clearance Surrounding Edge Bond

An adjacent component clearance surrounding the Xilinx device is necessary to have the 30° to 45° angle required for the edge bond dispenser to dispense the edge bond adhesive material. The surrounding component height and distance from the device is validated based on each unique product design layout.