Structural Adhesive Film

AF 555

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Product Application

Note: While this information is provided as a general application guideline based upon

typical conditions, it is recognized that no two applications are identical due to differing

assemblies, method of heat and pressure application, production equipment and other

limitations. It is therefore suggested that experiments be run, within the actual

constraints imposed, to determine optimum conditions for your specific application and

to determine suitability of product for particular intended use.

Note: Review and follow safety and precautionary information provided by

chemical supplier prior to preparation of this etch solution.

XVI. Surface Preparation

A thoroughly cleaned, dry, grease-free surface is essential for maximum

performance. Cleaning methods that produce a break free water film on

metal surfaces are generally satisfactory.

A. Aluminum: Phosphoric acid anodize (3M Test Method C-2780), Chromic acid

anodize with or without a chromate seal (3M Test Methods C-2801 or C-2782)

are preferred for maximum joint durability in moist environments. Optimized

FPL Etch has also demonstrated improved durability performance. Optimized

FPL Etch – 3M Company (3M Test Method C-2803 or ASTM D 2651)

1. Alkaline degrease – Oakite* 164 solution 9-11 oz./gallon of water at

190° ± 10°F for 10 to 20 minutes. Rinse immediately in large quantities of

cold running water (3M Test Method C-2802).

*Available from Chemetall Oakite, Berkeley Heights, NJ.

2. Optimized FPL Etch Solution (1 liter):

Material Amount

Distilled Water 700 ml plus balance of liter (see below)

Sodium Dichromate 28 to 67.3 grams

Sulfuric Acid 287.9 to 310.0 grams

Aluminum Chips 1.5 grams/liter of mixed solution

To FPL etch panels, place them in the above solution at 150 to 160°F (66 to 71°C)

for 12 to 15 minutes.

3. Rinse immediately in large quantities of clear running tap water.

4. Dry – Air dry approximately 15 minutes followed by a force dry at 140°F

(maximum).

5. Current theory suggests that both surface structure and chemistry play a

significant role in determining the strength and permanence of bonded structure.

It is therefore advisable to bond or prime freshly cleaned surfaces as early as

possible after preparing to avoid contamination and/or mechanical damage.

To prepare 1 liter of this solution, dissolve sodium dichromate in 700 ml of

distilled water. Add sulfuric acid and mix well. Add additional distilled water to

fill to 1 liter. Heat mixed solution to 66 to 71°F (150 to 160°F). Dissolve 1.5

grams of 2024 bare aluminum chips per liter of mixed solution. Gentle agitation

will help aluminum dissolve in about 24 hours.