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Design and Tape Selection Considerations

Choose the right tape for the substrate: Adhesives must flow onto the substrate surfaces in order to achieve intimate

contact area and allow the molecular force of attraction to develop. The degree of flow of the adhesive on the substrate

is largely determined by the surface energy of the substrate.

Use the right tape thickness: The necessary thickness of tape depends on the rigidity of substrates and their flatness

irregularity. While the 3M™ VHB™ Tapes will conform to a certain amount of irregularity, they will not flow to fill

gaps between the materials. For bonding rigid materials with normal flatness, consider use of tapes with thickness of 45

mils (1.1 mm) or greater. As the substrate flexibility increases thinner tapes can be considered.

Use the right amount of tape: Because 3M™ VHB™ Tapes are viscoelastic by nature their strength and stiffness is a

function of the rate at which they are stressed. They behave stronger with relatively faster rate of stress load (dynamic

stresses) and will tend to show creep behavior with stress load acting over a long period of time (static stresses). As a

general rule, for static loads, approximately four square inches of tape should be used for each pound of weight to be

supported in order to prevent excessive creep. For dynamic loads, the dynamic performance characteristics provided

on page 4 should be useful, factoring in the appropriate safety factors.

Allow for thermal expansion/contraction: 3M™ VHB™ Tapes can perform well in applications where two bonded

surfaces may expand and contract differentially. Assuming good adhesion to the substrates, the tapes can typically

tolerate differential movement in the shear plane up to 3 times their thickness.

Bond Flexibility: While an advantage for many applications where allowing differential movement is a benefit, the

tape bonds are typically more flexible than alternative bonding methods. Suitable design modifications or periodic use

of rigid fasteners or adhesives may be needed if additional stiffness is required.

Severe Cold Temperature: Applications which require performance at severe cold temperatures must be thoroughly

evaluated by the user if the intended use will subject the tape product to high impact stresses. A technical bulletin

“3M™ VHB™ Tape Cold Temperature Performance” (70-0707-3991-0) is available for additional information.

Adhesive

High surface energy

— Substrate

Adhesive

Low surface energy

— Substrate

This illustration demonstrates the effect of surface energy on adhesive interfacial contact. High surface energy

materials draw the adhesive closer for high bond strength.

Relationship of Adhesion and Surface Energy for 3M™ VHB™ Tape Adhesive Families

400-1100

Aluminum

Stainless Steel

Copper

Zinc

Tin

Lead

Anodized Aluminum

Glass

42-50

Phenolic

Nylon

Alkyd Enamel

Polyester

Epoxy Paint

Polyurethane

36-37

PVA

Polystyrene

Acetal

Powder Paint

18-33

EVA

Polyethylene

Polypropylene

Silicone

PTFE

NOTES: There are a wide variety of formulations, surfaces finishes and surface treatments available on substrate materials which can affect adhesion. This chart is intended

to provide only a rough estimate of the adhesion levels which can be expected on some common materials relative to a reference surface such as aluminum.

Light abrasion of surface will significantly increase adhesion levels on many materials, except when using tapes 4952/4932.

38-39

ABS

PVC

Acrylic

Powder Paint

100%

50%

0%

HIGH

LOW

MEDIUM

Surface Energy (Dynes/cm)

Multi-Purpose

Adhesive

General

Purpose

Adhesive

Low

T

emperature

Adhesive

NOTE: Low surface energy

adhesive may be less

affected by surface energy.

NOTE: Foam type can

affect and/or limit maximum

adheisve strength.