Page 15 of 20
©2011 Knowles Electronics
5. Environmental tests
5.1. Qualification tests
According to our milestone plan (Product Creation Process), a complete qualification test will be done
at design validation of products manufactured under serial conditions.
1x per year and product family a requalification takes place. The qualification process covers all tests
described under 5.5 and a complete inspection.
5.2. Reliability tests
1x per month and product family samples are taken and submitted to tests described under 5.5.2
5.3. Sample Size, Sequence
Unless otherwise stated 20 arbitrary new samples will be used to perform each test for both,
qualification and requalification test as described under 5.1 and 5.2.
5.4. Period of Shelf-Life
The period of shelf-life is 2 years.
5.5. Testing Procedures
5.5.1. Storage Tests
5.5.1.1. Cold Storage Test
Parameter Test Method and
Conditions
Duration Evaluation Standard
Low Temperature
Storage
(Ref. EN 60068-2-1)
-40°C
rel. humidity not
controlled
168h Measurements after 2 hours
recovery time.
All samples fully operable.
All acoustical parameters
according specification with
tolerances increased by 50 %.
5.5.1.2. Heat Storage Test
Parameter Test Method and
Conditions
Duration Evaluation Standard
Dry Heat Storage
(Ref. EN 60068-2-2)
+85°C
rel. humidity not
controlled
168h Measurements after 2 hours
recovery time.
All samples fully operable.
All acoustical parameters
according specification with
tolerances increased by 50 %.
