Lot Acceptance Testing (LAT)

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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%

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

10 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

12pcs / 9pcs

10pcs / 5pcs

5pcs

Custom Configurations Available Upon Request

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

Lot Acceptance Testing (LAT)

Advantages

Electrical Specifications

Conformance Testing

Qualification Testing

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