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TECHNOLOGY RELIABILITY

Overview of Substrates Level Reliability Tests

DSEM engages with an external laboratory that is ISO 17025 and ISO 9001:2000 certified where all the stress tests were performed.

Select stringent tests were chosen among the potential application of the substrates.
  • Thermal Stress Test- Mechanical stress is induced in the substrates where some parts are not free to expand or contract in response to changes in temperature. The purpose of this test is to determine whether the substrates can withstand the thermodynamic effects of the extreme heat to which they are exposed during assembly like surface mount, rework or repair process.
 
  • Temperature Cycling –Mechanical stress is induced by the alternating high and low temperature extremes. Permanent changes in electrical and/or physical characteristics can result in these mechanical stresses. This is to test the ability of the substrates to resist extremely low and extremely high temperature as well as their ability to withstand cyclical exposures to these temperature extremes.
 
  • Autoclave (Pressure Cooker Test) – This is to assess the ability of the substrates to withstand the severe temperature coupled with high humidity condition. This test will accelerate corrosion in the metal parts.
 
  • Wet High Temperature Storage – This is to assess the reliability of the substrates at long term storage at elevated temperature and humidity condition. This test will accelerate oxidation, intermetallic growth and other failure mechanisms that are triggered by elevated temperature /humidity with time.
 
  • Withstanding voltage test – This test consist of the application of a voltage higher than the rated voltage for a specific time between mutually isolated portions of the substrates and between isolated portions and ground. This is used to prove that the substrates can operate safely at its rated voltage and withstand momentary over potentials due to switching or surges and other similar phenomena. It serves to determine whether insulating and /or conductor spacing are adequate.
     
 
  • End point Measurements are as follows:
 
o   Visual/Mechanical
§ Visual Inspection (No peeling, blistering, and other manifestation that may affect the functionality and workability of the substrates)
§ Plating Adhesion Test ( IPC TM 650 method 2.4.10)
§ C-Scanning Acoustic Microscope (To check layer delamination)
o   Electrical Test ( Open/Short ; < 10Mohm is short)
  
Substrates Level Reliability Test Result
Tests
Reference
Conditions
Results
Electrical     (Failure Criteria)
Vis/Mech (Failure Criteria)
Thermal Stress
IPC TM 650 Method 2.6.8
3 X Lead-free reflow; 260°C Peak
0 failure         (note 4)
0 failure      (notes 1,2,3)
Solder Dip, 300°C, 60 seconds
0 failure        (note 4)
0 failure     (notes 1,2,3)
Temperature Cycle (TMCL)
JESD 22-A104
-40°, 150° C, 100 cycles (15 mins dwell, 5 mins transfer)
0 failure        (note 4)
0 failure    (notes 1,2,3)
Autoclave (PCT)
JESD 101- A
121 °C, 100% RH, 96 Hrs., 15 psig
0 failure        (note 4)
0 failure     (notes 1,2,3)
Wet High Temp Storage (WHTS)
JESD22-A101
85% RH, 85 °C, 168 Hrs.
Unbiased
0 failure        (note 4)
0 failure    (notes 1,2,3)
Withstanding Voltage Test (Alox: 75 microns min. thickness)
IPC TM 650 Method 2.5.7
2500 Volts, 30 sec test time
0 failure                      (no insulation break/rupture)
Notes:
1.     No peeling, blister nor obvious damage to the substrates.
2.     No plating metal and/or solder mask lifted with the adhesive tape.
3.     No layer delamination
4.     No short circuit
  
 
Overview of LED Reliability Tests
LED Arrays typically does not encounter catastrophic failures of which such failure the LED emits no light or very little light at normal current levels, as long as the product is handled and operated within the limits specified in the LED array application notes.
Parametric failures are failures that cause key characteristics to shift outside of acceptable bounds. The most common parametric failure for High Power LED is permanent Light Output Degradation over Operating life. Because heat is the crux of this light output degradation, the substrates’ thermal management property plays a vital role in inherently designing a reliable LED assembly.
The reliability tests performed are based on Semiconductor Qualification Test methodologies defined by JEDEC.
The test result proves that AloxTM Metal Substrate is able to support the requirements of thermal diffusivity and conductivity of High Power LEDs.
 

 LED Qualification Test Results

Test items
Reference
Stress Condition
Duration
Failure Criteria
Test Result
Temperature Cycling (TMCL)
JESD22-A104
-40° C, +120° C
15 mins Dwell
5 mins transfer
200 cycles
Note 1,2
0 failures
High Temperature Operating Life (HTOL)
JESD22-A108
85° C Board Temperature
Tj must not be exceeded
1000 hours
Note 1,2,3,4,5
0 failures
Temperature Humidity Operating Life (WHTOL)
JESD22-A101
MSL 1 Precond
85° C case temperature
85% Humidity
1000 hours
Note 1,2,4,6
0 failures
High Temperature Storage Life (HTSL)
JESD22-A103
120° C Ambient
1000 hours
Note 1,2,3,4,5
0 failures
Low Temperature Storage Life (LTSL)
JESD22-A103
-40° C Ambient
1000 hours
Note 1,2,3,4,5
0 failures
Room Temperature Operating Life (RTOL)
JESD22-A108
55° C Board Temperature
1000 hours
Note 1,2,3,4,5
0 failures
Low Temperature Operating Life (LTOL)
JESD22-A108
-40° C Board Temperature
1000 hours
Note 1,2,3,4,5
0 failures
Power Temperature Cycle (PTMCL)
JESD22-A105C
-40° C , 85° C
16 mins Dwell
42 mins transfer
4 mins off, 5 mins on
100 cycles
Note 1,2,3,4,5
0 failures
Mechanical Shock (MS)
JESD22-B104A
1500g; 0.5ms; 5 shocks/axis
NA
Note 1,2
0 failures
Mechanical Vibration (MV)
JESD22-B103A
20-2,000Hz; random;
4 mins; 4x/axis
NA
Note 1,2
0 failures
Solderability
JSTD-002
260° C +/- 5° C
10+/-1 sec
NA
Note 1,2
0 failures
Salt Atmosphere
JESD22-A107
5% salt solution;
 35+/- 5° C
pH =6.0-7.5 at 35° C
Deposition rate 34g/m2 /24 hrs
48 hours
Note 7
0 failures
ESD I (Human body model)
JESD22-114
8kV
NA
Note 1,2
0 failure
ESD II (Machine model)
JESD22-A115
400V
NA
Note 1,2
0 failure

Notes:

1. No Catastrophic Failure   5. Change in white color point, deltaX, deltaY<+/-0.01
2. No Parametric Failure   6. Lumen maintenance >50%
3. Lumen Maintenance >70%   7. No illegible marking
4. Change in Vf<10%