ESD Journal - The ESD & Electrostatics Magazine Corrosion Test Method

Purpose: To determine the corrosivity of the atmosphere in and contact with the inner surfaces of 3 - dimensional packages such as thermoformed,corrugated,injection molded and paperboard,etc.. This test method is designed to be application specific for the actual packages to be used. It is intended to be used in conjunction with but not replace the Contact Corrosivity Test Method 3005 of Federal Test Standard 101C and Mil-PRF-81705D.

Definitions:
Corrosion: Deterioration of a material by chemical action, usually as a result of oxidation, galvanic, acid, or alkali action. In this test method a visible change in the surface finish such as pitting or etching or the formation of loose or granular particles shall constitute corrosion.

Stain:Color changes formed only on the surface without any evidence of rust, pitting, etching, or deterioration of the surface. In this test stain shall be graded on a scale from 0 - 3 with three (3) being the worse.
0 = no noticeable changes - coupons appear the same as before the test
1 = slight color change which is barely perceptible in very few areas of the coupon
2 = color change which is perceptible in several areas
3 = severe color change of the coupon in general

Specimens: Specimens of the packages to be tested shall be taken at random. A minimum of three (3) specimen packages shall be used as a representative sampling of the package style to be tested.

All specimens shall be conditioned at 70- 76 degrees F, 45% - 55% RH for a minimum of 24 hours prior to beginning the corrosivity tests.

Test Coupons: The following metal coupons shall be used. Others more specific to the actual products to be packaged may be used also.

Low Carbon Steel , QQ-S-698, condition 5
Aluminum Alloy , QQ-A-250/4, 2024 bare
Copper, ASTM-B451, nominal thickness 0.014 inches or more
Silver Plated Copper, plating thickness 100 - 200 microinches
Tin-Lead Eutectic Solder (SN63) on Copper, thickness 200 - 500 microinches, J-STD-006
Stainless Steel, unified numbering system UNS31400
Kovar, ASTM-F15
All coupons shall be conditioned at 70- 76 degrees F, 9% - 15% RH for a minimum of 24 hours prior to beginning the corrosivity tests.
All coupons shall be clean of all contaminates prior to beginning tests. Cleaning and preparation methods shall conform to Federal Test Standard 101C, Method 3005

1. One each of the coupons shall be placed in each specimen package.
2. The coupons shall be arranged so that they are not in contact with each other. If the specimen packages are too small to hold all seven coupons without contact with each other, the number of specimen packages shall be increased to hold a total of three (3) coupons of each metal type.
3. The coupons shall be placed with one side in direct contact with the inside bottom of the specimen package.
4. The top side of the coupon shall be exposed unimpeded to the atmosphere of the inside of the package.
5. Each specimen package shall be closed as specified by the manufacturer.
6. Each specimen package shall be placed in a preconditioned chamber set to the following conditions: 118 - 122^dgrees F, 62% - 68% RH
7. The specimen packages shall remain at these conditions for 72 hours after which time they are removed and the coupons graded immediately.
Other conditions and periods of exposure may be used if they are determined to be more application specific to the package use.

Report:
1. Corrosion: determination of the existence of any corrosion. Comments shall be made on the observed severity of the corrosion.
2. Stain: grade of the stains observed on all coupons.
3. Test Conditions and coupons if different to those called out in this test method.

Pass/Fail Criteria:
No pass/fail criteria are implied in this test method. Each user of this test method must make the decision of pass/fail based on the application of the test packages.