premolded qfn packages for rf & mems applications -...
TRANSCRIPT
Premolded QFN packages for
RF & MEMS applications
Andy Longford – PandA Europe
ACP ... for MEMS
2PandA Europe - 2010
• MEMS sensory devices require Air-Cavity packages in
order to contact the media to be sensed ...
• The ACP is usually made up of 3 parts;
– a copper leadframe,
– a molded body (open, and not sealed)
– a lid.
• The ACP QFN type construction enables:
– Excellent thermal management
– Short Interconnects (for microwave applications up to 20-25GHz.)
– Small size “real estate”
– Multi options for lidding
Elements of a QFN package
Cover material **
Lid seal
Sidewall material**
Lid to lead seal
Base material and finish
**Sidewall and lid could be 1 piece … See Type 1
Or Sidewall and base could be one piece (Cavity Package approach)
Background
• “Standard” QFN options
1. Flat base + Cavity Lid = RJR type
2. Cavity base - Flat lid = :
1. Mirror
2. SemPac
3. Quick Pack
4. QLP
3. Cavity base – Cavity Lid = IEP type
Type 1• RJR types
Custom ACP QFN leadframes
Type 2
• Mirror Semiconductor– A Matrix array of (transfer)molded cavity
QFN units
• Sempac– As with Mirror, Transfer molded parts either
singulated or in arrays
• QuikPak– Plasma etched out ‘dummy’ package units
from standard QFN assembly lines
• QLP – A singular QFN package option from early
website ...
– Note QPL blue material
Type 3
• Cavity Base, Cavity Lid –
– Unique leadframe design
• Matrix format with ground i/o
– Unique Cavity Body
• Allows optional fill and seal
– Unique “waffle” lid
• One piece alignment
– Simplifies assembly processes
• Leadframe assy & transport
• Alignment and post assy dicing
RF component Package needs:
• Low height
• Air cavity
• Non-metallic lid
• Ground plane Die pad
• RF type I/O (ground signal ground)
• Short lead lengths
• Cost effective assembly ...
QFN for RF/MEMs Applications
• Low height
• Air cavity
• Lid options
• Leadframe options
• Scalable in sizes
• Gel seal compatible
• Cost effective assembly ...
New QFN Package options ...
• QFN IEP – Inverted Exposed Pad
– Interplex design project for
Improved Thermal management
of Power devices
• Downpad QFN
– New design for high frequency
applications ....
Down Pad QFN
• New Design Issues:
– Flatness of Die pad ?
– Die pad should not
have raised edge
– Molding cannot be
done with flat Plate
(not an RJR style)
– Cost ....?
Flat form base,
Cavity lid and
downpad frame
IEP design ...
• Basic design, 2 leadframe style
• Utilise “Cimptech” Molding
iQLP ...
• “Quantech” Polymer
• Process defined
• LCP type Materials
• Meets MSL3
• Direct Bond to Copper
• AuSi Eutectic compliant (420˚C)
• CTE match to Copper
• High Strength LCP
• Quantech is an expensive LCP
• Specialist Process – costs
• Developed for LDMOS
• QFN .... not ready yet
• Market ?
• Cost ?
• Quantities ?