9890 1 IN X 36 YD 3M, 9890 1 IN X 36 YD Datasheet - Page 5

• Manufacturer Part Number: 9890 1 IN X 36 YD
• Description: THERM COND ADH 10MIL 1"X36YD
• Manufacturer: 3M
• Type: Acrylic Adhesiver

Specifications of 9890 1 IN X 36 YD

• Size / Dimension: 1.00" W x 36 yd Roll
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 3M9592; 70006178894

Technical Bulletin
System Design and Performance for 3M
II. High/Low
III. Bond Building/
Temperature
Performance
(continued)
Rework
Heat and Humidity
The adhesive absorbs very little moisture (< 0.2% by weight), therefore the presence
of humidity does not in itself lead to loss of adhesion. However, metal substrates
prone to formation of loosely bound oxides may suffer accelerated mechanical failure
when in contact with Tapes 9882, 9885, and 9890 Tapes under these conditions.
Examples of such metals include copper, iron, and in some cases, untreated aluminum.
Therefore it is advised that such metals be passivated with appropriate coatings or
treatments before applying the adhesive.
Low Temperatures (² 20¡C)
Temperatures below the glass transition temperature, Tg (-20¡C to 30¡C), cause the
adhesive to become a glassy, rigid material, compared to its rubbery state above Tg.
Low temperatures do not in themselves harm the adhesive or the bond strength.
However, below Tg the bonded parts are more prone to delamination from applied
stresses such as high frequency shock, or from internal stresses such as those due to
mismatched coefficients of thermal expansion of the substrates (e.g. ceramic bonded
to aluminum). Vibration damping, a useful property of the adhesive in the rubber
state, it is also reduced at low temperatures.
Temperature Cycling
Temperature cycles that drop below -20¡C or dwell well above 85¡C may cause
failures as described in the other section above. Delaminations from coefficient of
thermal expansion mismatch may combine with the oxidation effect to cause
additional failures not found when the conditions act separately. For moderate
temperature cycles the adhesive actually can be beneficial to stress relief of rigid
assemblies. Because its modulus is below that of metals or ceramics, some of the
shear stress from temperature cycling may be taken up in strain of the adhesive,
helping to protect the bonded parts.
Information is presented below on the rates of bond building of the 3Mª Thermally
Conductive Tapes 9882, 9885, and 9890 on various material surfaces and a general
procedure for rework.
In general the adhesion strength of bonds made with these tapes increases over time
(the Òdwell periodÓ) a process called bond building. The bond building effect is not
due to a curing reaction, since the adhesive is a fully cured material. Rather the cause
is due to a combination of mechanical and chemical forces that act over time.
Mechanical interlocking occurs from the flow of the adhesive on a microscopic scale
into pores of the substrate. Surface forces establish in a wetting phenomenon the rate
and extent of which depends on the chemistry of the substrate. The degree of bond
building therefore depends on the details of the substrate surface and chemical
makeup. Examples of quite different bond building characteristics on ceramic and
anodized aluminum substrates are give on the following page.
TM
Thermally Conductive Tapes 9882, 9885, 9890
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