Handbook of Solvents - George Wypych - ChemTech - Ventech!

14.8 Electronic industry 899
14.8.2.1.4 Water-based cleaning agents based on MPC � Technology
(MPC = Micro Phase Cleaning)
Figure 14.8.4. MPC � cleaning technology.
Cleaning agents based on MPC Technology
can be formulated either neutral or alkaline.
The media combine the advantages
of solvent and aqueous-based formulations
revealing an extremely large process window.
2,3 The principle of MPC systems is
shown in Figure 14.8.4.
The MPC media are based on formulations
consisting of alkoxypropanols and
water. Their phase behavior is dependent
on the temperature, agitation, and the
dragged in contamination. The microphase,
which is generated through temperature or media agitation, is responsible for the removal of
the lipophilic components of the contamination. The ionics are removed by the aqueous
phase. 12 Since the ability to keep the organic contamination in the microphase is limited
through the degree of loading, the lipophilic substances are expedited into the aqueous
phase. Due to their lipophilic character, they precipitate out of the fluid and can be removed
by a simple filtration device. As a result the loading of the cleaning fluid with contamination
is minimal thereby minimizing the amount of organic components that finally pollute the
subsequent rinsing stages. 3
Alkaline pH, that is essential for the saponification process, can be realized through
biochemical buffer systems, predominately aminoalkanoles.
Due to the described cleaning principle, extremely long bath life times can be guaranteed
with excellent cleaning results. 2,3,12 The MPC � media are tailor made for all kinds of
different cleaning equipments such as high and low pressure spray systems, spray under immersion,
and ultrasonic applications. 3 These cleaning agents based on MPC � Technology
also contain low quantities of volatile organic compounds. However, due to this state of the
art technology the percentage of VOCs are reduced to a minimal level.
14.8.2.1.5 Advantages and disadvantages of aqueous cleaning media
Prior to the implementation of a cleaning process in a production line, the following criteria
need to be taken into consideration:
1) Cleaning performance
The substrates that have to be cleaned should be free of all kinds of residues that might
have some negative influence on the functionality of the substrates. The contamination consist
predominantly of flux residues, solder paste or SMT adhesive. Another important aspect
with respect to the cleaning result is the compatibility between substrates and the
cleaning chemistry. It is painless to remove the contamination while destroying the substrates.
2) Process reliability and process costs
Every engineer tries to implement a process with a wide process window, and minimizing
potential problems during production. While evaluating a cleaning process, the process
parameters should be stable over a long period of time. As a result the equipment down
time can be minimized, due to maintenance thereby optimizing the overall process cost.