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VOC |
: Volatile Organic Compounds |
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Simple definition |
: Fast evaporating solvents (alcohols) |
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EPA definition |
: Any Substance Containing > 1.0% Organic Material with a Vapor Pressure > 0.1mm Hg @ 20 °C. |
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In our industry |
: VOC-Free = Water-Based Solder Fluxes |
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Wave soldering with VOC-free fluxes may bring many advantages. However, some process considerations need to be taken into account. This becomes most obvious when you consider the differences in physical and chemical properties between isopropyl alcohol and water (the base for VOC-free fluxes).
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Properties |
H2O |
IPA |
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Melting point [°K] |
273.000 |
183.0000 |
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Boiling point [°K] |
373.000 |
355.0000 |
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Heat of fusion [kcal/mole] |
1.440 |
1.2800 |
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Heat of vaporization [kcal/mole] 25 °C |
10.510 |
10.8500 |
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Density of liquid [g/cc] |
1.000 |
0.7850 |
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Molar volume liquid [cc/mole] |
18.000 |
60.1000 |
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Vapor pressure at 273 °K [atm.] |
0.006 |
0.0424 |
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Dielectric constant 20 °C |
80.100 |
20.1800 |
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Dipole moment [Debye] |
1.840 |
1.5800 |
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Surface tension at 25 °C [mN/m] |
71.990 |
20.9300 |
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Viscosity 25 °C [mPa.S] |
0.890 |
2.0380 |
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Viscosity 75 °C [mPa.S] |
0.378 |
0.5760 |
Tips for the successful implementation of VOC-Flux technology
- Verify the compatibility of your type(s) of solder-resists with VOC-Free flux technology
- Work with board vendor(s) to reduce variation of the surface state of the solder resist:
o Curing rate
o Ionic contamination (Preferably under 0.5 micrograms/cm2 of NaCl-equivalents
- Reconsider the design of pallets with regard to water entrapment
- Old pallets partially may have delaminated. Water entrapment may be an issue!
- A good spray fluxer must have a nozzle positioned not too far from the board providing
o A quantifiable and controlled film thickness
o Minimum overspray
o Good thru-hole filling
- Medium wave length Infra Red preheating elements are preferred the 1st preheat zone
- Forced convection helps to create a good plateau temperature level in proceeding zones
- For recommended preheat profiles, see the User's Guidelines of the products concerned.
When - for one or more of the above reasons, or for any other reason - your process window currently appears too small for full VOC-free water-based fluxes, an excellent drop-in replacement for alcohol-based fluxes may appear to be Low-VOC fluxes!
Process Technology
Under this section you will find titles of technical papers published by Cobar specialists. You will also find information on Research Institutes that can help you in the process implementation of VOC-free.
Assistance VOC-Free & Low-VOC Process Implementation
Our experienced engineers are ready to help you on a personal basis with in-house seminars, specific process issues or on-the-spot troubleshooting.
VOC-Free Solder Pastes
The flux-systems in both our conventional and lead-free solder pastes are VOC-free. Moreover, they make an excellent performance in squeegee-printing as well as with Direct Imaging Systems. So, there is no need to change a flux-system when changing to another method of printing or when moving to lead-free! read more...
VOC-Free & Low-VOC fluxes
Lead-free and VOC-free fluxes go hand-in-hand! Both technologies generally require more heat. Moreover, the extra power of the activator-system in the water provides the right answer to the generally more difficult to wet non-leaded surfaces.
Also Low-VOC fluxes will provide a perfect match to the lead-free wave solder process. Moreover, they can be considered as a drop-in replacement for conventional alcohol-based fluxes. read more...
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