Speedline - Accel - Microcel Cleaner  
  The MicroCel and MicroCel 2 are semi-automatic cleaning systems that utilize a
centrifugal cleaning process to provide superior cleaning results. The MicroCel
and MicroCel 2 are functionally identical with the difference being:
• The MicroCel is equipped with a large-opening shallow wash reservoir
intended for cleaning circuit boards exceeding 10 inches on a side. It is typically
equipped with a mounting fixture that accommodates varying board
sizes.
• The MicroCel 2 is designed to clean circuit boards and substrates up to 10
inches by 10 inches and is typically equipped with a cassette fixture capable
of holding a number of boards or substrates of uniform size.
Hereafter unless otherwise noted, MicroCel will be the term used to describe the
operation and characteristics of the MicroCel and MicroCel 2.
Theory of Operation

Products to be cleaned in the MicroCel are mounted in a fixture that is attached
to a shaft extending down from the robot head. A programmed sequence is then
initiated by the operator which automatically lowers the robot head, dispenses
solution, spins the board, drains the solutions and raises the robot head when the
sequence is complete. The operator can select rotation speed, duration and
number of reversals (cycles) for each interval of the wash, rinse and dry
sequence. Separate heater controls for elevating the temperatures of the wash
and rinse solutions and the drying air are operator adjustable.

The MicroCel harnesses centrifugal and coriolis energies by spinning the product
on center or about center within an enclosed chamber. A solvent immerses the
spinning product during the wash cycle. The harnessed energy forces the solvent
in a direction parallel to the plane of the product driving it under components with
very small clearances and into dead spaces. Adhered contamination is solubilized,
suspended in solution and driven off the product. Next is an optional immersion
DI rinse process. During the spray rinse cycle, the MicroCel dispenses a second
solvent on the top and bottom of the spinning product flushing away residual
contamination and wash solvent. The drying cycle is accomplished by continuous
spinning of the product while introducing hot air or nitrogen into the enclosed
process chamber.

Robot Head Lift Mechanism

The robot head is structurally mounted to the frame through two sturdy slide
assemblies. It is vertically driven by a pneumatic cylinder and support system to
provide smooth, reliable and safe motion. The robot has a 16” vertical travel that
requires about 5 seconds to complete. Check valves and the pneumatic logic
assure that the robot head will not fall in case of house air or electrical failure.
 
 
  • Microprocessor Control System
  • Cooling System
  • Chilled Water
  • Zero Discharge
  • Zero Discharge Resistivity Readout
  • Rinse System
  • Heating System
  • Spill Containment
Microprocessor Control System  
Automatic operation of the MicroCel is performed by a Mitsubishi F series
programmable logic controller (PLC). Using relay ladder language, all the system
parameters, interlocks, timing and supervision are programmed into the controller.

Cooling System

The standard wash reservoir contains a blanked-off flange to accept a cooling
system option. The cooling system using a 3/8” diameter stainless steel coil with
customer supplied tap water or a cool (chilled) water system to provide a
capability to reduce the temperature of the wash solvent. A thermostatic system
controls the water flow to maintain wash solvent at a preset temperature.

Chilled Water

This option will lower the temperature of the wash solution. The water must be at
the desired temperature before circulating in the MicroCel. Cooling water must be
at the desired temperature before circulating in the machine. Cooling water enters
the system through the fittings marked COOLING IN and COOLING OUT on the
right rear panel of the system. The temperature at which the solenoid valve
admits cooling water is set on a Cal-Stat thermostat probe above the resistance
temperature device (RTD) on the wash reservoir.

Zero Discharge

As an option, the MicroCel can be configured with a zero discharge system. With
this system water is not discharged from the machine when using certain semiaqueous
cleaning solutions, EC-7R for example, and subsequently no customer
drain facility is necessary.
The zero discharge system:
• collects all used rinse water from the process chamber,
• separates the cleaning solution from the rinse water,
• arrests microbial growth in the rinse water,
• filters the rinse water to 5 micron,
• passes the rinse water through a carbon absorption bed,
• recharges the rinse water to its previous deionized state,
• heats the rinse water for reuse, and
• returns the recovered cleaning solution (a few CCs per cycle) to the cleaning
solution reservoir where it is filtered for reuse.

Zero Discharge Resistivity Readout

The zero discharge option includes a resistivity probe and controller. The
controller provides digital readout of resistivity levels, setpoint, alarm and system
shut down when the resistivity level falls below set point. The controller is
mounted on a hinged panel behind the right front door panel. The probe is located
at the output of the mixed resin filter prior to the entrance of the rinse water into
the process chamber.

Rinse System

The MicroCel uses a 7 gallon passivated 316 stainless steel reservoir that
operates under pressure supplied by the customer’s tap water or DI water system
to provide rinsing capacity. When using recoverable solvents for rinsing, an
optional decanter and pump system is required. Refer to Zero Discharge option
later in this section. The rinse solution is gently sprayed onto the top and bottom
spinning board surfaces allowing centrifugal forces to cause effective rinsing.

Heating System

An optional heating system uses two 1.1 KW cartridge heaters inserted into 3/4”
diameter stainless steel heater wells located horizontally along the bottom of the
reservoir. These heater wells allow heater replacement without draining the
system. The system includes closed loop temperature controller and 2 cartridge
heaters.

Spill Containment

An optional drip pan is available to capture 110% of the machines liquid capacity.
Also available is a sensor that will initiate a system alarm when liquid is detected
in the drip pan.