PEM Whitepaper - Page 23

APPENDIX

**Table A1 - Package Related Failure Mechanisms Identified with Plastic and Hermetic IC's**
DESCRIPTION	STRESS/SOURCE	RESPONSE	ACCELERATING TEST	PLASTIC	HERMETIC
Cracked Die	Thermal	Electrical Short/Open	Temperature Cycle	X	X
Cracked Die	Mechanical	Electrical Short/Open	Impact Shock		X
Wire Breaks	Thermal	Electrical Open	Temperature Cycle	X	X
Wire Breaks	Mechanical	Electrical Open	Vibration, Centrifuge		X
Wire Lifts	Thermal	Electrical Open	Temperature Cycle	X	X
Wire Lifts	Mechanical	Electrical Open	Vibration, Centrifuge		X
Wire Lifts (intermetallic)	Thermal	Electrical Open	High Temperature Storage	X	X
Cracked Package Seals	Thermal	Loss of Hermeticity	Temperature Cycle		X
Cracked Package Seals	Mechanical	Loss of Hermeticity	Impact Shock		X
Corroded Seals, external (Pin-to-Pin Shorts)	Moisture	Loss of Hermeticity	Humidity, Salt Atmosphere		X
Interface Delamination	Thermal	Reduced Moisture Resistance	Temperature Cycle	X
Internal Water Vapor	Package Assembly	Al Corrosion	Low Temperature Bias Life		X
Moisture Ingress	Moisture	Al Corrosion	Temperature/Humidity/Bias Autoclave, HAST	X
SMD Cracked Package (Popcorn Effect)	Thermal	Reduced Moisture Resistance/Elect. Opens	Humidity/Solder Shock Sequence	X
Metal Deformation/ Cracked Passivation	Thermal	Electrical Shorts/Opens	Temperature Cycle	X
Lifted Die	Thermal Mechanical	Electrical Shorts/Open Thermal Designation	Temperature Cycle Impact Shock, Centrifuge		X
Die Attach Voids	Package Assembly	Thermal Dissipation Low D/A Strength Cracked Die	Bias Life Temp Cycle, Centrifuge	X	X
Loose Die Attach, Sealing Materials, and Particles	Package Assembly	Electrical Shorts	Vibration/Shock PIND		X

**Table A2 - Comparison of General Industry Sampling & Qualifications for Military Hermetic Versus Automotive Plastic Microcircuits**
DESCRIPTION OF TEST	MILITARY HERMETIC (Mil. Std. 883)			AUTOMOTIVE PLASTIC (Typical)
DESCRIPTION OF TEST	LTPD	#LOTS	DURATION	LTPD	#LOTS	DURATION
Burn-In 100%	(PDA = 5%)	All	168 Hours	(PDA = 0.5-2.0%*)	All	48-168 Hours
Operating Life Qualification	5	1	1k Hours	2 - 3	1 or 3	1k - 2k Hours
Biased Humidity Qualification	Not Specified	Not Specified	Not Specified	2 - 3	1 or 3	1k - 2k Hours
Temp Cycle Qualification	15	1	100 Cycles	1.5 - 3	1 or 3	1k Cycles
Mechanical Qualification	15	1	- - -	Not Specified	Not Specified	Not Specified
Group A Sampling	2	All	- - -	1	All	- - -
* Values are for when PDA is specified. Sample burn-in to LTPD of 2% typically performed when PDA not specified. Note: This chart compares similar stress conditions with the exception of biased humidity and mechanical.

**Table A3 - Reliability Monitors - Comparison of Military Hermetic and Intersil Plastic**
HERMETIC MILITARY (MIL-STD-883) QUALITY CONFORMANCE INSPECTION (QCI)			PLASTIC COMMERCIAL MATRIX MONITOR
DESCRIPTION	SAMPLE/ ACC. NO.	FREQUENCY	DESCRIPTION	SAMPLE/ ACC. NO.	FREQUENCY
Group B Resistance to Solvents Bond Strength Solderability(8 Hours Steam Age)	3/0 22/0 10/0	Each Lot Each Lot Each Lot	Matrix I HTOL (125�C or 175�C, 48 Hours) HAST (135�C/85% R.H., 48 Hours) Autoclave (96 Hours) Thermal Shock (200 Cycles)	45/0 45/0 45/0 45/0	2X/Month 2X/Month 2X/Month 2X/Month
Group C HTOL (125�C, 1k Hours)	45/0	1X/12 Months	Matrix II HTOL (125�C, 1k Hours) THB (85/85, 1k Hours) Autoclave (192 Hours) Storage Life (150�C, 1k Hours) Temp Cycle (1k Cycles)	45/0 45/0 45/0 45/0 45/0	1X/Month 1X/Month 1X/2 Months 1/2 Months 1X/2 Months
Group D 1. Physical Dimensions 2. Lead Integrity 3. Thermal Shock (15 Cycles) Temp Cycle (100 Cycles) Moisture Resist (10 Cycles) 4. Shock Vib. Var. Freq. Acceleration 5. Salt Atm. (24-240 HPS) 6. Internal Wafer Vapor 7. Adhesion of Lead Finish 8. Lid Torque	15/0 15/0 15/0 15/0 15/0 3/0 15/0 5/0	1X/6 Months 1X/6 Months 1X/6 Months 1X/6 Months 1X/6 Months 1X/6 Months 1X/6 Months 1X/6 Months	Matrix III Solderability (8 Hrs. Steam Age) Brand Adherence Lead Integrity Physical Dimensions Flammability UL-94 SPC Monitored (Eqv. to Hermetic) Bond Strength Die Shear Solderability >4 Hours Steam Age >8 Hours Steam Age	22/0 15/0 15/0 11/0 5/0 SPC SPC - Z Chart Recording Recording	2X/Month 1X/Month 1X/Month 1X/Month 1X/Quarter 1X/Shift 1X/Oven/Cycle 1X/Shift 1X/Week
Note: Mil-Std-883 requires assembly locations to have an additional monitor program to Mil-Std-976 (i.e., Bond Strength/Die Shear, etc.) which has not been covered by this table.

Table A4 - Best Industry Practices - Design for Reliability and Continuous Improvement

DIE RELATED

IMPACT ON RELIABILITY

Electric (E) Field Plating

Reduces mobile ion instability

Particulate & Contaminant Control

Lowers defects in oxides and ionic contamination

Layout considerations for high stress areas.

Reduces stress cracking of passivation at die corners.

Denser passivation, sandwich layers of SiO2/SiNx

	Better integrity against fabrication defects.
	Robust to thermomechanical stress.
	Better moisture/ion barrier.

Passivation overlap of die oxide edges.

Provides moisture/ion barrier

Advanced planarization for reduced stress

Reduced metal displacement and passivation damage.

Wear-out failure mechanisms eliminated from useful life at the die level.

Elimination from useful life the intrinsic wear-out failure mechanisms EM (Electromigration), TDDB (Time Dependant Dielectric Breakdown), Hot carrier injection, Corrosion, and Device Stability.

Reliability critical process node list.

SPC control of variables effecting quality and reliability

PACKAGE RELATED

IMPACT ON RELIABILITY

Mold compounds:

Higher glass transition temperatures.

	Less thermomechanical stress at high temperatures
	More robust to thermal cycling

Low ionic (Low Halides, and Alkali) compounds

Reduced corrosion and increased device stability

Use of modified filler material.

Reduced point stress damage on die surface.

Low stress mold compounds
for large die and complex
geometries.

Reduced passivation cracking and metal deformation

Ion getters.

Corrosion reduction and greater device stability.

Reduced frame retardants

High temperature stability and corrosion reduction

Automated in-line mold machines

	Less wire sweep.
	Less voids in plastic
	Better control of molding process

Die attach materials with low stress, low ionics.

	Less stress on die
	Increased device stability

Lead lock holes, moisture groves, locking bars on lead frame.

	Increased moisture resistance and corrosion reduction.
	Increased mechanical integrity

Optimum die to paddle spacing.

Lower stress on die

Automated assembly processes

No human handling, less contamination, and less process variability

SPC critical node list and process monitors.

Variability reduction and Continuous Improvement.

EXPANDED MATERIALS CHARACTERIZATION

IMPACT ON RELIABILITY

Acoustic Microscopy

	CSAM
	SLAM

Non destructive analysis of Plastic products for voids, die cracks, and delamination isolation. DOX with CSAM yields Continuous Improvement.

Thermal Characterization Methods:

	Differential scanning calorimetry
	Thermogravimetric analysis
	Thermomechanical analysis

Broader materials characterization and referencing enhances continuous improvement of raw materials.

Moisture weight gain/loss measurements

	Determine sensitivity to delamination and popcorn cracking.
	Material analysis
	Determine dry pack requirements.

Applications of dye penetrants

Being further developed to enhance tracing moisture ingress on lead frame to Plastic interfaces.

**Table A5 - ASIC Wafer fabrication, 6", Critical Node List Example**
MAJOR FLOW STEP	CRITICAL PARAMETER	TYPE OF CONTROL	CRITICAL NODE YES/NO
EPI Deposition P-Diffusion Sink Deposition Nitride Dep & Etch Local Oxidation BN Drive Gate Oxidation Poly Deposition Poly Doping Poly Etch DMOS Drive N+/P+ Ion Implant Interlevel Dielectric First Metal Deposition First Metal Etch Intermetal Dielectric Sec. Metal Deposition Second Metal Etch Passivation Deposition In-Line Probe	Sheet Resistance EPI Thickness Oxide Thickness Sheet Resistance Post Etch Dimension Oxide Thickness Sheet Resistance Oxide Thickness Poly Thickness Sheet Resistance Post Etch Dimension Oxide Thickness Sheet Resistivity Oxide Thickness Deposition Rate Thickness Post Etch Dimension Thickness Reflectivity Oxide Thickness Deposition Rate Post Etch Dimension Passivation Thickness Device Parameters	XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R Z-Chart XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R XBAR-R Z-Chart XBAR-R Test Site Sample	YES YES YES YES YES YES YES YES YES YES YES YES NO YES YES YES YES YES YES YES YES YES YES NO
Note: Other general or tool related critical controls such as Capacitance Voltage (CV) test for the cleanliness of furnaces and deposition tools are maintained in-line.

**Table A6 - Plastic DIP Assembly Critical Node List**
MAJOR FLOW STEP	CRITICAL PARAMETER	TYPE OF CONTROL	CRITICAL NODE YES/NO
Wafer Mount Saw Die Visual QC Lot Acceptance Die Attach Die Attach Cure Wire Bond QC Lot Acceptance Mold Chemical Deflash Mold Cure Trim/Form Solder DIP QA Lot Acceptance Brand QA Lot Acceptance To Test	Kerf width, DI Resistivity Visual Quality Visual Quality Visual Quality Oven Temp Die Shear Pull Strength Visual Temp Force Ball Shear Visual Quality Visual Quality X-Ray Visual Quality Oven Temp Visual Quality Visual Quality Solder Thickness Solderability Visual Quality Brand Perm Visual Quality	XBAR-R Monitor AQL AQL NP-Chart XBAR-R Z-Chart XBAR-R NP-Chart XBAR-R XBAR-R XBAR-R AQL NP-Chart AQL NP-Chart XBAR-R NP-Chart AQL XBAR-R AQL NP-Chart AQL AQL	NO YES YES NO YES YES YES NO YES YES YES YES YES NO YES NO

Table A7 - Best Practices Recommended for PEM Handling and Board/System Processing

PROBLEM

PREVENTION

Storage

	Environmental vapors in ambient and moisture can be corrosive to the leads of packages and cause dendritic growth on insulating surfaces between leads.
	Storage environment if moist can lead to moisture uptake in plastic. With voids or delamination, accumulation of monolayers of moisture and contaminants can change pH or conductivity of moisture sufficiently to start galvanic corrosion of metallization.

	Control environmental ambient gases. Dry N2 storage.
	Eliminate Human handling of product.
	Dry N2 purge storage, minimize storage time.

Storage in moist environments may lead to "Popcorn Cracking" or delamination in certain surface mount device packages during solder reflow operations.

	Dry pack (sensitive package types)
	Store surface mount devices at <30�C and <55% R.H.

Electrostatic Discharge (ESD) - applicable to hermetic and PEMs

	Human handling without proper ESD prevention can lead to damaged products.
	Dropping parts out of tubes or in handlers onto a grounded surface can lead to triboelectric charge damage as well as non destructive oxide charging (surface leakage and reflected leakage).
	Handlers that have ESD hot zones due to a lack of grounding or oxidized surface such as anodized surfaces, floating rails, etc., can cause ESD damage.
	Conformal coating materials sprayed on PCB's can develop extreme ESD potential. Also sprayed DI water is an ESD source.

	Use monitored wrist straps at work station, with ionization if necessary.
	Reduce sliding packages on insulated surfaces.
	Reduce dropping distance or purge with ionization.

	ESD gauge all handlers, pick and place machines, belt transports and transition points for charged surfaces. Improve grounding and charge dissipation
	Adjust coating and cleaning processes to minimize charging, i.e., use ionization, add CO2 to DI water, etc. Low pressure applications.
	Follow Mil-Handbook 263,
	ESD Control Handbook Mil-Std 1686, JEDEC, Pub 108-A

Handling to Prevent External Contamination

Human handling contaminants (body oils, salts, makeup, lotions) on the external surfaces of a package may diffuse through plastic with moisture, leading to ionic instability or corrosion.

	Use automated pick and place equipment.
	If handled, use clean, ESD safe cots or gloves which have been shown not to transfer residuals or ionic contaminants to surfaces.
	Thorough board cleaning.

Processing Without Halides

Halides in flux or cleaning agents or residual halides on boards may diffuse through the plastic with moisture and lead to corrosion of bond pads, interconnect and lead frame.

	Use high purity electronic grade halide free flux's and paste as well other high purity chemicals in board assembly or coat processes.
	Thorough board cleaning.

Alkali Metal Ion Free Processing

Alkali metal Ions (positive or cations) such as Na+, Li+, K+ are mobile and can cause surface leakage and device drift.

	Use high purity electronic grade materials, gases, and liquids that certify as alkali free.
	Control particle counts and analyze residue for alkali metals. Eliminate sources.
	Eliminate human handling.
	Thorough board cleaning.

Surface Mount Device Solder Reflow

Thermal Shock due to temperature gradient and peak/temperature/time excursions in combination with sufficient absorbed moisture can lead to delamination of mold compound to die, paddle, and lead frame.

	Sensitive surface mount device packages not dry packed should be baked dry at 125�C for 24 hours and used within 48 hours on board attach.
	Use pre-heating in the solder attach process.
	Monitor temperature profiles of the solder attach equipment
	Pay special attention to the temp/time dwell of the peak solder temperature zone.
	Standards - IPC, JEDEC A112

Metallic Free Processing

Fine pitch packages, (<25 mils) are susceptible by their reduced lead pitch to residual solder and metallic fines which react with bias and moisture to cause leakage and shorts.

	Clean up residual solder paste and residual solder.
	Eliminate sources of metallic fines in automated equipment.
	Conformal coat PCB or selected surface mount devices.

Proper board packaging.

Mil Plastic - 30 AUG 94