3M
™
VHB
™
Tapes
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.
Adhesive
— Substrate
High surface energy
Low surface energy
— Substrate
Adhesive
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
Estimate of % of Maximum
3M™ VHB™ Tape Adhesion
100%
Lo
G
en
NOTE:
Low surface energy
adhesive may be less
affected by surface energy.
w
M
er
al
tu
ra
Pu
re
rp
Te
m
ul
ti-
50%
pe
Pu
rp
NOTE:
Foam type can
affect and/or limit maximum
adheisve strength.
M
od
ifi
os
os
ed
Ad
e
e
he
Ad
ve
Ad
Ac
si
he
he
ry
si
ve
si
lic
ve
0%
Surface Energy (Dynes/cm)
HIGH
400-1100
Aluminum
Stainless Steel
Copper
Zinc
Tin
Lead
Anodized Aluminum
Glass
42-50
Kapton
®
Phenolic
Nylon
Alkyd Enamel
Polyester
Epoxy Paint
Polyurethane
MEDIUM
38-39
ABS
Polycarbonate (Lexan
®
)
PVC
Noryl
®
Acrylic
Polane
®
Paint
Powder Paint
36-37
PVA
Polystyrene
Acetal
Kynar
®
Paint
Powder Paint
LOW
18-33
EVA
Polyethylene
Polypropylene
Tedlar
®
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.
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.
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3M [ 3M ELECTRONICS ]
