PD 955 M
SMT-Adhesive
Thermosetting Polymer SMT-Adhesive for High-Speed Dispensing

Description
PD 955 M 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 high-speeddispensing.
It allows for very low Z-Height-returns.
Special advantages
- Very wide processing window, no tendency to string.
- Specially developed for high-speed dispensing.
- Dispensing with very low Z-Height-return possible.
- 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).
- Constant batch-to-batch quality.
Physical characteristics
Colour: red
Density: 1.2 g/cc
Homogeneity: no particle >50 μm
Adhesion: ³ 25 N/mm2 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 ascending curves
[s-1] [Pa·s]
PD 955 M 30 10 - 40
Haake Rotovisco RV 20, PK 100, PK I/2°T,
plate/cone, without border, temperature: 23 °C.
Program: ascending curve 0-40 s-1, 6 min.
Electrical characteristics
Surface insulation resistance and electrolytic corrosion
property: see reverse.
Processing
The adhesive is suitable for machine and manual
dispensing.
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 125°C 150°C 180°C
8 ' 3 ' 1.5 ' 1 '
* Optimal curing conditions depend on the curing oven.
Cleaning
Before curing:
The uncured adhesive can be removed with Zestron HC and
other Zestron and Vigon cleaning materials - see separate
application recommendations.
The cleaned parts must be completely dry before installing
them in the machine.
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.
Packing
The adhesives PD 955 M can be filled in various machinespecified
syringes.

Storage
Storage time:
6 months in a refrigerator, at a storage temperature of 5 -
12°C.
Storage in a refrigerator is recommended.
Remark: Storage at temperatures >30°C should be
avoided.
See reverse for additional information

Test results with the SMT-adhesive PD 955M according to Siemens Norm SN 59651**
Report date: April 29, 1996
Item:* Test Requirements Results
2.1 Characteristics good visible colour, filled in syringes
bubble-free,
particle size < 50 μm
red colour
bubble-free
particles < 30 μm
2.2 Viscosity acc. to the agreement passed
3.1 Storage Conditions acc. to manufacturer´s data
6 months
passed
3.2 Open potlife min. 8 hours passed
3.3 Dispensability reproducible - without stringing passed
3.4 Tack time min. 8 hours passed
3.5 Components’ adhesion
before curing of adhesive
position change £ 0.15 mm < 0.1 mm
3.6 Cleanability completely cleanable Zestron HC
4.1 Curing characteristics acc. to manufacturer´s data 125 °C, 3 min.
4.2 Electrolytic corrosion effect known value should be no worse passed
according to IEC 426 than A 1.4
4.3. Surface insulation resistance > 1.1010 Ohm 3.4.1011 Ohm
(comb sample test)
4.4 Electrolytic corrosion effect no blistering, no dendritic growth passed
(comb sample test)
4.5 Mass loss at working temperature mass loss £ 1 % passed
4.6 Adhesive spreading during curing increase of diameter £ 10% passed
4.7 Components’ adhesion
after curing of adhesive
> 5 N/mm2 per component 0603: 15.6 N/mm2
0805: 14.4 N/mm2
1206: 15.9 N/mm2
SOT23: 11.2 N/mm2
SO14: 30.0 N/mm2
4.8 Components’ adhesion > 1 N with the component 1206 1.38 N
after curing of adhesive
(measured in soldering bath)
4.9 Reparability SMD replacement without damage passed
*According to SN 59651, Issue November 1994.
**The tests were performed in the Siemens Central Laboratory ZPL1TW22 in Berlin.
Person who performed the tests: Mr. Trodler