NEPP - NEPAG PEMs Evaluation Information

NASA's use of Commercial-off-the-Shelf (COTS) Plastic Encapsulated Microcircuits (PEMs) electronic components in Space applications has raised serious concerns and issues about their inherent reliability, quality and design performance robustness. To fully understand, to assess and to mitigate risks, NASA is undertaking a thorough investigation and extensive screening and packaging evaluations on various COTS components from selected manufacturers.

This website provides background information about this investigation and the published results. For more information about this effort, contact Mike Sampson or Mike Sandor. Link to PROJECT OVERVIEW

Bookmarks for this page:

Test Flow (starting at the top)

Die Oriented Qualification Tests

Package Sample Qualification

Package Moisture Resistance

Results

High Speed Op-Amp

Precision Voltage Reference

Packaging Moisture Resistance Final Report

MSL Evaluation Results

MSL and Moisture Resistance Test Results

CSAM Data for the Multiplexer

Other Supporting Documents including:

Activation Energy Calculator

Reliability of Low Tg in COTS PEMs for Space

Moisture Test Terminology Compared

DRAFT COTS PEMs Guideline Document

The following is an example of the Test Flow used in the evaluation:

Step	Screen	Required	Reject Criteria	Special Instructions
1	DPA	1. SEM / Cross section of steps,via, contacts 2. Xray Fien Focus 3. Glass transition temperature for plastic package(2 ea/date code). Ref: Mil-Std-1580B	Any abnormal processing especially with metalization. Thinning, voids, notches, or apparent abberations will be recorded.
2	Serialization	Laser Serialization or other means for traceability
3	1^st Electricals	+25°C, 70°C, 0°C, test to data sheet, Read & Record		Calculate/Compare Vendors AOQL from rejects.
3A	FITS Verification Sample Static B/I	1000 Hr. 125ºC B/I, +25°C, 70°C, 0°C with functional subgroups, R&R at 168 hrs, 500 hrs, 1000 hrs	B/I conditions for devices with T_op-max < 125ºC: 105°C: 105ºC for 2300 hrs 85ºC: 85ºC for 2620 hrs
4	Temp Cycle	-65°C to 150°C	10 cycles ; Mil-Std-883 method 1010 Cond C
5	X-ray	MIL-STD-883, Method 2012	Inspect for wire sweep (top view)
6	C-SAM	Inspect for delamination and or cracks between LF & MC, die surface to MC, die attach to die pad, die pad to MC.	Delamination, voids, or cracks: >10% of area. Rejects will be identified and recorded. Photographs will be reviewed by the Specialist
7	Electricals	+85°C, +125°C, -40°C, -55°C, test to datasheet	Any part failing to meet data sheet parametrics at the temperatures specified. Data to be recorded/reviewed for outliers.	Bag and tag/ remove hard failures
8	Dynamic Burn-In	168 hours @ +125°C, Vcc = max rating	B/I conditions for devices with T_op-max < 125ºC: 105°C: 105ºC for 400 hrs 85ºC: 85ºC for 440 hrs	Junction temp <25C below Tg. Parts to be bagged and tagged
9	Electricals	+25°C, +70°C, +85°C, +125°C, -40°C, -55°C with functionality	Data to be recorded/reviewed for outliers/drifters
10a	Screening Data Analysis & Formatting
10b	Screening Data Engineering Review/QCI Sample Selection
Die Oriented Qualification Sampling Tests
11	Dynamic Burn-In Life Test	1000 hr., 125ºC	Life test conditions for devices with T_op-max < 125ºC: 105°C: 105ºC for 2300 hrs 85ºC: 85ºC for 2620 hrs	Junction temp <25C below Tg.
12	End Point Electricals	+25°C, +70°C, +85°C, +125°C, -40°C, -55°C, test to datasheet	Any part failing to meet data sheet parametrics at the temperatures specified. Data to be recorded/reviewed for outliers/drifters	Do interim R/R at 250 & 500 hrs for 1000 hr life. Do interim R/R at 500, 1000 and 1500 hr for 2000+ hr life test.
13	DPA	Die visual inspection/Bonding inspection at die pad and lead frame		Photo documentation required. Perform destructive bond pull on virgin & screened samples for each date code, 5 pcs per date code (3 min). Sniff for Bromine and Phosphorous released agents.
Package Oriented Qualification Sampling Tests
14	Lead Solder Heat Exposure	1^st Half of Samples: Surface Mount Heat Exposure Ref JESD22-A113-B Applicable Steps: Para 3.1.2 Para 3.1.4 Para 3.1.6 VPR only	2^nd Half of Samples: Resistance to Soldering Heat Exposure Ref JESD22-B106-B Notes: para 4.2;Solder bath will be 315C+or-10C Hermeticity tests are not applicable to PEMs	All parts must be accepted for mark permanency before commencing with Group D testing.
14A	Post Electricals	25ºC, test to data sheet
15	Temp Cycle Qual	Ta = -65ºC to +150ºC	1000 cycles; Mil-Std-883 method 1010, Cond C
16	Post Temp Cycle Electricals	+25°C, +85°C, +70°C, +125°C, -40°C, -55°C, test to data sheet	Data to be recorded and statistically compiled	Do interim R/R at 500, and 700 cylces. Perform 100% CSAM and do DPA on 4 pcs upon completion
17	HAST Qualification	130C/85% RH, JESD22-A110-B, 96 hrs		For part type with 85ºC T_op-max, lot is spilt (11 and 11 pcs). Conditions for 1st lot is 110ºC/85% RH for 264 hrs. Conditions for 2nd lot is 130ºC/85% RH for 96 hrs.
18	Post HAST Electricals	+25°C, 85°C, 0°C, +125°C, -40°C, -55°C, test to data sheet	Data to be recorded, within 48 hrs of ramp-down, and statistically compiled	Perform 100% CSAM and do DPA on 4 pieces upon completion.
19	Vibration	MIL-STD-883, Method 2007, Cond. A (20 g’s)
19A	Post Electricals	Test to data sheet at 25ºC
20	Cold Startup	8 hr soak, minimum at -55ºC, unbiased		Test at nominal Vcc supply for functionality (in situ at -55ºC). Test at 25ºC to data sheet with R&R
Package Moisture Evaluation
1	CSAM	Topside, backside, thruscan
2	Flux/Pretinning	Using Sn/Pb	Water soluble flux used
3	Temperature Cycling	JESD22-A113-B
4	Bake	100ºC, 24 hrs	Intended to remove moisture
5	Moisture Sensitivity Test	MSL 1 or 3	Moisture level selected is per the mfr’s guarantee	Volt Diff Amplifier was level 3, all other devices were level 1
Subflow for type of soldering environment (22 pieces through each subflow 6a, 6b and 6c). All parts saw all subflows Except, Op-Amp, Analog MUX and Volt Reference did not go through the 6b flow.
6a	Hand Soldering	Each lead exposed to heat for 5 sec max, tip temp = 335ºC max
6b	IR/Convection	Ref JESD22-A113-B, 245 - 250ºC max
6c