Edge Bonding Implementation

Versal Adaptive SoC 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. AMD requires the use of the Zymet UA-2605-B edge-bonding material. 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, AMD recommends the parameters shown in the following table.
Table 1. Process Parameters for Edge Bonding
Process Parameter Range Specification
Needle size Range: 25—15 gauge, where needle diameter (D) is 20 gauge (0.91 mm) typical
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 (6 mm/sec typical)
Value pressure Range: 10 to 60 psi (14.5 psi typical)

The adhesive is dispensed along the perimeter of the assembled component at a width of 2.5–3.0 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. AMD 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.

To ensure proper mechanical bonding between the package and PCB, the edge bonding feature must penetrate the edge bonding material under the package substrate by 1.8 mm. This requirement is necessary for packages with coplanarity ≤ 200 µm, and BGA pitch of 1 mm or 0.92 mm, to pass physical qualification tests such as thermal cycle, power cycle, and shock and vibration requirements. It is necessary for special applications such as telecom, industrial, and data center applications.

Important: Some package devices have an overhang substrate that can result in the first row of the BGA not being covered by edge-bonding material. In other scenarios, the first BGA row could cover up to 90% of the BGA. See the following scenarios.
Figure 1. Edge Bonding Scenarios

Figure 2. Edge Bonding Adhesive Placement Parameters

Component Clearance Surrounding Edge Bond

An adjacent component clearance surrounding the AMD 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.