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Heraeus Assembly SMT Adhesive PD955
© Coprise LLC. 2007 all rights reserved
PD 955 SMT-Adhesive
Thermosetting Polymer

SMT-Description:

PD 955 PY is a thermosetting single-component,
solvent-free polymer adhesive, developed
especially for the surface mounting of SMT
components on to PCBs and for use on bare
substrates.

The rheology is especially adapted for printing
application with thick stencils.

Special advantages:

* Ideal, high dot form and excellent consistency
of the glue dots.
* Specially developed for printing with thick
stencils.
* Very high green strength prevents component
movement during placement.
* Form stable glue dots.
* Excellent adhesion with standard and also
with difficult-to-glue components.
* Very low humidity absorption. Steep
temperature increases and very short curing
times are possible without danger of formation
of air bubbles or worse
adhesion.
* High surface insulation resistance (SIR).

Physical characteristics:

Colour: yellow
Density: 1.2 g/cc
Homogeneity: no particle >50 µm
Adhesion: 25 N/mm 2 at room
temperature, after curing in conventional box
oven, 5 min /125°C, Cu-nail on SO component,
with a low-stress incapsulation compound.

Viscosity:

Shear rate D Viscosity ascen. curve
[s -1 ] [Pas] PD 955 PY 30 50 - 150
Cone / plate, without border, 2° cone,
temperature: 23°C.
Processing:

The adhesive is suitable for printing with
metal and plastic stencils.

Processing temperature: 23-28°C

Processing humidity: <70% r.H.

Curing: The standard curing conditions are:
125°C/3'. Max. curing temperature should not
be higher than 200°C.
The minimum* curing times are shown in the
following list. 100 °C/8' 125°C/3' 150°C/1.5'
180°C/1'. * Optimal curing conditions depend
on the curing oven.

Cleaning:

Before curing:
In order to avoid an attack of the cleaning
medium on the stencil frame adhesive, a use of a specially designed cleaner, e.g. Zestron SD 301 is recommended.

When small dots are printed e.g. 0.5 mm, or
in case of a bad contamination of the stencil
with the glue, we recommend the use of
Zestron ES 200 for pre-cleaning and
afterwards Zestron SD 301 for final cleaning.
However the cleaning with Zestron ES 200 must be done very carefully, by hand, to avoid a contact of Zestron ES with the stencil
frame adhesive.

After curing:
Because of the known residual
thermoplasticity of the cured adhesive,
defective components can be easily replaced
by heating (with hot air) the cured adhesive
joint above 100°C.
After removing the component (torsion
movement), the hot air should be focused on
the remaining adhesive in order to remove it
with a sharp tool.

Storage:
Storage time: 6 months in a refrigerator, at a
storage temperature of 5 - 12°C.
Issue from 13.06.2002 WS-DK

Order information:

Call: 956-541-7393


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