Cleaning is the removal of undesirable substances, thin films or residues from a surface. The ability to perform delicate cleaning without damage to the underlying part is a critical benefit of MicroBlasting.
Coating Removal Circuit Board

Where Used

Thermocouple MgO removal

AEROSPACE

  • Thermocouples – removing MgO to expose contacts for bonding on heat-sensing harnesses
  • Circuit boards – conformal coating removal for replacement of failed components
  • Ceramic components – removing metalization
  • Turbine blades – cleaning casting material, laser remelt and coatings from air holes
  • Wire stripping
  • Gyro blocks – removing polishing compound
Dental Mold Cleaning

DENTAL LAB

  • Crowns – removing oxides from surface
  • Pressable ceramics – divesting (Empress Process)

FOSSILS

  • Fossil preparation – removing the matrix surrounding an embedded fossil

ART RESTORATION

  • Paintings – removing residues
  • Cleaning stone masonry
Stent Automated Surface Finish Preparation

MEDICAL

  • Guidewires – removing PTFE coatings
  • Conformal coating removal
  • Ceramic components
  • Pacing leads
  • Stents – removing oxides and HAZ from laser-cut Nitinol stents
  • Heart valves – removing graphite core on mechanical valves
  • Pacemakers – removing excess encapsulation material
  • Catheters
  • Defibrillator leads – selectively removing silicone insulation to expose an electrical conductor
Hot runner nozzles residue removal

INDUSTRIAL CONTROLS

  • Conformal coating removal
  • Molds – removing EDM recast and discoloration
  • Hot runner nozzles – cleaning residue buildup to increase lifespan of expensive nozzles
  • Ceramic components
Turbine Blade Surface

POWER GENERATION

  • Turbine blades
  • Solar panels – edge deletion
  • Solar panels – selective exposure of the molybdenum layer
Probe ring epoxy removal

ELECTRONICS

  • Probe cards – removing excess epoxy
  • Trimming resistors
  • Wire stripping
  • Conformal coating removal
  • Ceramic components

How to

The selective cleaning process uses the abrasive qualities of MicroBlasting to carefully erode layers of unwanted material from a base substrate. The process takes advantage of the different physical properties of the two layers. Brittle materials can be removed from soft ductile layers, or soft ductile layers can be removed from brittle layers. The difference between selective cleaning and controlled erosion is that controlled erosion is performed on a single material type or layers of material with the same properties.

Removing a soft ductile material from a brittle base substrate

  • Abrasive selection: Use a sharp abrasive that will cut through the soft ductile layer, but not hard enough to erode the brittle substrate underneath. The most common starting point for these applications is sodium bicarbonate due to its needle-like shape and soft composition. Plastic media and walnut shell are also frequently used.
  • Particle velocity: During the development phase, start at a low velocity/pressure to avoid damage. Gradually increase pressure to speed up the removal process, but use caution as high particle velocities may cause damage to the substrate.

Removing a brittle layer from a soft ductile substrate*

  • Abrasive Selection: A dense abrasive, like aluminum oxide or glass bead, transfers energy into the brittle layer, fracturing it. When it strikes the ductile layer, a broad area absorbs and then releases the energy of the striking abrasive. The elastic nature of the substrate keeps it from eroding.
  • Particle velocity: The soft ductile substrate could be burned if too much energy is transferred to the target. Gradually increasing pressure speeds up the removal process, but high particle velocities may cause damage to the substrate.

*MicroBlasting works well when the brittle layer has strong cohesive forces and weak adhesion properties.

Manual/Automatic

MicroBlasting is a flexible process for selective cleaning. A manual system is ideal for lower volumes. High variation in part geometry or blast location benefits from the skilled eye of an operator. For instance, excess epoxy on probe rings unevenly distributes, and fossils come in all shapes and sizes—from trilobites to T-Rexes.

Some applications may be good candidates for automation, but lack the volume. During the prototyping phase of a new pacemaker, the design is optimized in low volume. Once this technology moves into production, MicroBlasting transitions seamlessly from manual stations to automated systems. The core blaster stays the same. Automation provides parts handling and control over the process. This means that the whole process does not need to be re-qualified, it can simply be expanded.

Pacemaker Cleaning
Twist Wrist in Comco JetCenter Automated MicroBlasting
Fossil Rock Artifact Cleaning

PTFE Removal from Guidewires

Guidewires are typically coated with PTFE to improve lubricity. It is far more effective to coat guidewires in long reels than in individual lengths. After the wire is coated and cut to length, sections of the coating need to be removed. The critical aspects of this application are:

  • the delineation from coated to uncoated must be sharp.
  • the coating must be completely removed.
  • the integrity of the wire must be maintained.

Sodium bicarbonate is an ideal abrasive media for this application because of its physical properties and water solubility. The particles are sharp enough to cut through the PTFE’s long fibrous strands, but soft enough to leave the guidewire unharmed. Sodium bicarbonate is listed as a 3 or 3.5 on Mohs. It is ideal for interventional use, because it leaves no residue following a standard cleaning process.

PTFE Guidewire Removal
Fossil Matrix Removal

Matrix Removal on Fossils

Removing the calcium and rock layers that surround a fossil is challenging and tedious. This matrix can be closely bonded to the fossil itself. While a pneumatic hammer may be used to make the initial “rough” cut, a skilled operator must remove the remaining matrix. The highest potential for damage to a fossil happens during the removal of the final layer. MicroBlasting’s accuracy and control combined with the right abrasive reduces risk to priceless artifacts during this critical operation.

Common abrasives for matrix removal are sodium bicarbonate and pumice. Both abrasives chip away at a brittle matrix without damaging the delicate fossil underneath. The process should be done in a customized WorkStation equipped with a magnifier to enhance control and precision.

Conformal Coating Removal on PCBs

Traditional processes for testing and removing components from printed circuit boards involve either chemicals or extreme heat, both of which have significant drawbacks. MicroBlasting’s accuracy is effective on high-value boards and other applications where the coating only needs to be removed from selected areas. Blasting parameters can be configured to differentiate between coating material and the board. Abrasive can be quickly changed to handle a wide variety of different coating types, such as polyurethane, acrylics and parylene.

Plastic media is sharp enough to cut through the coating, but soft enough to protect the solder mask on the board. Plastic media is commonly coated in a static dissipative material to minimize ESD buildup.

Sodium bicarbonate is a better choice for tougher coatings. The sharp, needle-like shape of sodium bicarbonate cuts through epoxy and urethane. Blasting at low pressures prevents these sharp particles from damaging the solder mask. Sodium bicarbonate is also water soluble, simplifying cleanup.

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