QFN

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 3x3 to 10x10 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