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Heraeus Assembly Paste Tack Flux TF38
Low Residue No Clean Tack Flux


TF38 is a low residue no clean tack flux
designed for use in the attachment of chips to
various substrates. This tack flux series is
based on a synthetic oligamer and rheology
modifier. The use of these raw materials
provides for a higher tolerance to thermal
cycling and compatibility with most underfill
compounds. TF38 leaves a minimal clear
residue that may be left on the
substrate or removed with cosolvents and/or

Physical Properties:

% Solids 19.0+/-0.3%
Viscosity 1 @25°C 8 to14 Kcps
Peak Tack Force 2 2.6 g/mm 2
Density 0.9+/-.05 g/ml
1 Haake PK100 viscometer, PQ1B sensor @
13.6 S *1
2 IPC TM-650- 2.4.44

Residue Properties:

Flux Activity 1 LO
>1 *10 8 Ohms
>2 *10 4 Megaohms
Electromigration 2 Pass
Copper Mirror 1 Pass
Cl - /Br - (AgCrO4)1 Pass
1 IPC J-STD-004 2 Bellcore TR-NWT-000078

Stencil Printing:

Typical printing protocols for solder pastes
apply. Contact printing with the stencil
thickness being equivalent to the desired flux
deposit should be used. Metal squeegees
should be used to minimize scooping.

Attack angles of 45° are optimal.
Stencil life of eight hours can be obtained
if the ambient conditions are controlled to
below 25°C and relative humidity
between 40 and 60%

Dip Application:

Bumps should be dipped to 0.5 mils or
slightly less to transfer sufficient volume.
Flux depth on the applicator should be set
to allow for enough flux to be present to
compensate for the maximum variability of
bump height on the chip to leave the
minimum deposit on the smallest bump.

Flux depth should also be maintained to
keep flux a minimum of 1.0 mil from the
chip surface to avoid flux creep on the die
surface. Applicator life of 8 hours can be
achieved if the ambient conditions are
maintained below 25°C and relative
humidity between 40 and 60%.

Order information:

Call: 956-541-7393
production solutions for
Service: 956-541-7393