Design and Implementation of VLSI Systems (EN1600) Lecture 32: Pad Frame Design and Packaging
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Transcript of Design and Implementation of VLSI Systems (EN1600) Lecture 32: Pad Frame Design and Packaging
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S. Reda EN1600 SP’08
Design and Implementation of VLSI Systems(EN1600)
Lecture 32: Pad Frame Design and Packaging
Prof. Sherief RedaDivision of Engineering, Brown University
Spring 2008
[sources: Weste/Addison Wesley – Tanner Manual]
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S. Reda EN1600 SP’08
Packaging choices
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S. Reda EN1600 SP’08
Chip-to-Package Bonding
• Traditionally, chip is surrounded by pad frame– Metal pads on 100 – 200 mm pitch
– Gold bond wires attach pads to package
– Lead frame distributes signals in package
– Metal heat spreader helps with cooling
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S. Reda EN1600 SP’08
Pad frame
So far we looked at core designThis lecture we look at pad frame design
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S. Reda EN1600 SP’08
MOSIS AMI 0.5u Tiny Chip frame
Tanner reserves one of the left pins for VDD and one of right pins for GND
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S. Reda EN1600 SP’08
Generic pad layout
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S. Reda EN1600 SP’08
ESD protection
• Static electricity builds up on your body– Shock delivered to a chip can fry thin gates– Must dissipate this energy in protection circuits before it
reaches the gates
• ESD protection circuits– Current limiting resistor– Diode clamps– Diodes must be large to sustain significant current
• Example: Consider charge on human body discharged at a rate (current) = 10 uA for 1us at to a capacitor C=0.025pF → Voltage buildup = 400V destroys the transistor gate
PADR
Diodeclamps
Thingate
oxides
Currentlimitingresistor
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S. Reda EN1600 SP’08
Example 1: PADARef offers basic ESD protection
Simplest pad
metal 2 distributes VDDmetal 1 distributes signal D
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S. Reda EN1600 SP’08
Example 2: PADOUT
Pad has internal buffer
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S. Reda EN1600 SP’08
Automatic generation of pad frame in Tanner Tools
1.Add the pad library to your S-Edit design2.Modify your design to use the pads.
Naming convention: if you name nets getting into a pad as PAD_L1 places the pad at the first left location in the pad frame.
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S. Reda EN1600 SP’08
Automatic generation of pad frame in Tanner Tools
3. In L-Edit, change SPR setup to
Use the new library with the pads and press initialize setup
In padframe setup, Change the layout size to 1.5mm x 1.5mm
In padroute setup, make sure you have these design rules
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S. Reda EN1600 SP’08
Automatic generation of pad frame in Tanner ToolsFinally run the place and route and make sure to mark “PadFrame generation” and “Pad route”
You might get a few DRC violations in metal2 that you would need to fix yourself