QFN Package Application

Scheme Description

Quad Flat No-lead (QFN) packages are based upon a copper lead frame that uses half-encapsulation technology to expose the rear side of the die pad. Typical die sizes are 3×3 to 10×10 mm, although smaller sizes are becoming more common.

There are three main family types：

Power QFN : thickness 1.5-2.5mm (~0.5mm copper lead frame)
Standard HE QFN : thickness 0.8-1.2mm (Up to 0.2mm copper lead frame)
Thin QFN : thickness 0.4-0.6mm (Up to 0.15mm copper lead frame)

Major Considerations:

• Cut quality:
• Chipping
• Burrs
• Lead smearing
• Melting
• Delamination

Blade life:

· end of life is usually caused due to end of exposure

Saw:

· 7223, Fully automatic dicing with built-in cleaning and UV curing, extended Y-travel for dual panel large size QFN’s and 2.4 kW High torque spindle.

Blade:

• 2”, 3” and 4” Resin blades “E”, “T” and “D” matrixes and Sintered Blades ”Q” matrix
• Diamond grit size: 45 – 105 microns for Resin blades and 40-55 microns for Sintered blades
• Thickness: .008” – .020”

Process Parameters:

• Feed rate: Half Etched substrates 30-100 mm/sec, Full Copper substrates 10-40 mm/sec
• Spindle speed: 2” : 25 – 30 krpm 3” : 15 – 25 krpm 4” : 8 – 15 krpm
• Multi panel mounting on UV tape
• Blade preparation – Mostly, override process over one substrate until reaching final feed rate