Step 2 - Solvent Drying
Approximate recommended drying times for PTM-Series Stencil Print (SP) type Phase Change Material (based on 0.25mm – 0.3mm thickness):
- 15 hours @ 25°C
- 3.5 hours @ 50°C
- 20 mins @ 80°C
- 2-3 mins @ 100°C
Solvent evaporation vs Time in open airPlease note that times are based on the part's temperature and are best measured using a thermocouple. As a pro tip, it is also possible to determine the time required based on the 20-22% height reduction of the Phase Change Material
Different types of Stencil Print materials will dry in different times and temperatures. We generally offer SP, SPM and SPS version. You can imagine them as Normal, Medium and Slow dry. In Room temperature, normal pastes dry pretty fast, at ~2.5 hours. Medium pastes can take up to two days while Slow versions can dry for more than two days... Of course this changes into minutes at 100°C. At 100°C, Normal ones take ~2.5minutes, Medium ones ~7 minutes and Slow ones can take more than 10 minutes to dry.
Thickness Shrinkage
All of our PCM materials come in both Pad and Paste versions (SP). The SP versions are identical to the pads, with the main difference being the added solvent that makes them more viscous. With this form come a couple of questions, first one being, "How much does the solvent shrink and how does this affect the final bondline thickness?".
To answer this we printed in a few different target thicknesses, namely 0.2mm, 0.25mm and 0.3mm. Then we put these samples in the oven for 20 minutes at 80°C for the solvent to dry and measured the outcome. From the resulting thicknesses, we concluded that, regardless of the print thickness, the dry version is ±20% thinner than the thickness right after print. So, for example, to get a 0.25mm final (dry) bondline we need a 0.3mm initial thickness.
Sample # | Thickness right after print (mm) | Thickness after Solvent dry (mm) | Height reduction |
1 | 0.299 | 0.239 | 20.07% |
2 | 0.247 | 0.195 | 21.05% |
3 | 0.194 | 0.154 | 20.62% |