Lot Acceptance Testing (LAT)

 Printable PDF version of datasheet

Advantages

Lot Acceptance Testing provides screening and qualification tests to enable the use of Ohmcraft’s standard parts in flight applications (Aerospace/Space).  Ohmcraft can screen and qualify its resistor products to MIL-PRF-55342, MIL-PRF-49462, NASA EEE-INST-002 (Level 1 or Level 2) or a custom test plan.  LAT Testing includes but is not limited to:

  • Thermal Shock
  • Solderability
  • Short Term Overload
  • Power Conditioning
  • TCR
  • Terminal Strength
  • High Temperature Exposure
  • Load Life
  • Resistance to Solvents

Electrical Specifications
                                                                                                                

Value R

R Ω 

Resistance Value in kΩs, MΩs, GΩs, or TΩs

Tolerance

± X% at <Test voltage> V

Resistance Tolerance measured at specified voltage

TCR

< [Ordering Coder TCR] ppm/ºC (Hot to TmaxºC, Cold to TminºC)
< 2*[Ordering Coder TCR] ppm/ºC (Hot to 125ºC, Cold to -55ºC)

TCR referenced to 25ºC

Working Voltage

<Application voltage> V

Voltage across the resistor during application operation

Max Voltage Rating

<Max Voltage> V

Maximum Voltage based on resistance value or case rating

Max Power Rating

<Max Wattage> W

Maximum Wattage based on resistance value or case rating

Conformance Testing

 Pre-Cap Visual Inspection:

        Prior to Conformance Test

 Conformance Test - 100% Screening

                      Visual Inspection:

                               i. Magnification: 30x to 60x

                      Mechanical Inspection:

                      DC Resistance

                               i. Per MIL-STD-202, Method 303
                               ii. Measured at specified test voltage for resistance tolerance

                      Thermal Shock:

                               i. Per MIL-STD-202. Method 107, Test Condition B (modified)
                               ii. 5 cycles (MIL-PRF-55342), 10 cycles (NASA Level 2) or 25 cycles (NASA Level 1)
                               iii. Min. temp -55ºC, Max temp 125ºC

                      High Temperature Exposure (SMT):

                               i. 100 hours at 125ºC

                                                                                         - or -

                       Power Conditioning (Leaded):

                               i. 100 hours at Working Voltage at 25ºC

                       Final DC Resistance:

                               i. Per MIL-STD-202, Method 303
                               ii. Measured at specified test voltage for resistance tolerance

                       Conformance PDA: 5% (NASA Level 1 or MIL-PRF-55342), 10% (MIL-PRF-49462) or 15% (NASA Level 2)

 

13 pcs

 

 

100%

 

3pcs. (minimum)

100%


 

100%



 

100%

 

 

100%

 

100%


 

Qualification Testing


 

1)  Group 1:

a. Conformance Testing: Basic Screening

2)  Group 2:

a. Solderability

         i. MIL-STD-202, Method 208

b. Resistance to Solvents (Leaded)

         i. MIL-STD-202, Method 215

3)  Group 3:

a. Temperature Coefficient (TCR)

         i.  Per MIL-STD-202, Method 304
         ii. Reference Temperature: 25ºC

b. Low Temperature Storage

         i.  -65ºC no load dwell for 24±4 hours
         ii. +25ºC ambient no load dwell for 2-8 hours

c. Low Temperature Operation

         i.   -65ºC no load dwell for 1 hour
         ii.  Working Voltage for 45 minutes
         iii. +25ºC no load dwell for 24±4 hours

d. Short Time Overload

         i. 2x Working Voltage for 5 seconds

4)  Group 4:

a. Resistance to soldering heat

         i.  MIL-STD-202, Method 210
             Test Condition B (modified)
         ii. 260ºC for 20 seconds

b. Terminal Strength (Leaded)

         i.  MIL-STD-202, Method 211
             Test Condition C
         ii. 16 ounces ± 1 ounce for 10 seconds

 

NASA Sample Size
(Level 1 / Level 2)

 

100%

 

3 pcs / 3 pcs

 

3 pcs / 3 pcs

 

 

10 pcs / 6 pcs


 

10 pcs / 6 pcs


 

10 pcs / 6 pcs



 

10 pcs / 6 pcs

 

 

9 pcs / 6 pcs



 

9 pcs / 6 pcs

 


 

5) Group 5:

a. Shock (Leaded)

         i. MIL-STD-202, Method 213B
            Test Condition I

b. Vibration (Leaded)

         i. Per MIL-STD-202, Method 204, Test Condition D

6) Group 6:

a. Load Life

        i.  Per MIL-STD-202, Method 108
        ii. Working Voltage for 1000 or 2000 hours at 25ºC

7) Group 7A:

a. Resistance to Bonding Exposure (SMT)

        i.  Solder mounted to a ceramic test plate
        ii. 4-12 hours stabilization at 25ºC\

7) Group 7B:

a. Solder Mounting Integrity (SMT)

        i.  Solder mounted to a ceramic test plate
        ii. 2kg, 90º Angle, 30 seconds minimum

8) Group 8: -- No Applicable Tests--

9) Group 9:

a. High Temperature Exposure

        i. 125ºC for 100 hours

 

NASA Sample Size
(Level 1/Level 2)

 

9pcs / 6pcs


 

9pcs / 6pcs

 

 

12pcs / 9pcs


 

 

10pcs / 5pcs


 

 

10pcs / 5pcs


 

 

 

5pcs

Custom Configurations Available Upon Request

Please consult with our knowledgeable sales staff for help
specifying custom parts to meet your needs.