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Slot-Die Coater User Manual


Slot-Die Coater

  • Precise
  • Space-Saving Design
  • High Coating Uniformity

Available From £7200

1. EU Declaration of Conformity (DoC)


Please refer to the full PDF or print user manual for the EU Declaration of Conformity (DoC) information.

2. Overview


Slot-die coating is an advanced thin-film deposition technique that is compatible with large-scale manufacturing processes such as roll-to-roll and sheet-to-sheet deposition systems. The technique is part of a class of coating techniques called ‘metered coating techniques’, in which the thickness of the deposited layers is solely dependent upon the rate of solution flow and the speed at which the substrate moves.

Ossila Slot-Die Coater
Figure 2.1 Ossila Slot-Die Coater

This compact slot-die coating system is aimed at research and development teams who are looking to transition away from techniques that are incompatible with large-scale processing, such as spin coating. The Ossila Slot-Die Coating System has been designed for simple operation, easy maintenance, and affordability. An integrated high-precision Syringe Pump allows for accurate and reproducible flow rates, which are essential for controlling thin-film thicknesses.

The substrate stage is levelled using a simple three-point levelling system combined with high-precision digital height gauges. Additionally, the stage incorporates a heating element allowing substrates to be heated up to 120°C.

The slot-die head is made from stainless steel, ensuring compatibility with a wide range of chemicals. The internal design of the head uses a simple ‘coat hanger’ manifold to distribute the solution evenly across the coating width, resulting in minimal thickness variation.

Slot-Die Coater gantry schematic
Figure 2.2 Slot-Die Coater gantry schematic
1 Digital Height Gauge
2 Manual Micrometer
3 Safety Clip
4 Slot-Die Head
5 Luer Lock Adapter
6 Gauge Roller
7 Heated Stage
8 Thumb Screw
Slot-Die Coater syringe pump schematic
Figure 2.3 Slot-Die Coater syringe pump schematic
9 Motor
10 Coupling
11 Lead Screw
12 Wing Nut
13 Rail Guide
14 Plunger Pusher
15 Plunger Clip
16 Flange Clip
17 Syringe Holder
18 Barrel Clamp

3. Specifications


The Slot-Die Coater specifications are shown in Table 3.1 and Table 3.2.

Table 3.1. Slot-Die Coater specifications

Maximum Hotplate Temperature 120°C
Maximum Travel Length 100 mm
Minimum Stage Speed 100 μm s-1
Maximum Stage Speed 50 mm s-1
Minimum Syringe Dispense Rate 0.021 µL/s for a 1mL syringe
Maximum Syringe Dispense Rate 1 mL/s software limit
Maximum Substrate Thickness 13 mm
Stage Surface Flatness <20 μm*
Stage Surface Roughness (RMS) 3 μm*
Stage Levelness <50 μm*
Power Supply Input: 90-264 VAC 50/60Hz Output: 24 VDC, 6.25 A
Dimensions

Width: 280 mm

Height: 190 mm

Depth: 360 mm

Weight <10kg

*Values determined at a stage temperature of 21°C.

Table 3.2. Slot-Die Coater head specifications

Slot-Die Head Material Stainless Steel
Slot-Die Head Coating Width 50 mm
Slot-Die Shim Thickness 100 μm
Luer Lock Adapter Stainless Steel M5 to Luer Lock Adapter
Tubing and Connector Material PTFE Tubing, high density PP Luer lock connectors

4. Warranty


The Slot-Die Coater is covered by Ossila’s two-year warranty. There are no user-serviceable parts in this unit other than the fuse (which is accessible externally). Any modification or alteration may damage the equipment, cause injury, or death. It will also void your equipment’s warranty. If servicing or repair is needed, please contact Ossila to organise a return. Our service department will also quote for any repairs to faults that occur outside the 2-year warranty period.

4.1 What the 2-year Ossila Warranty Includes

  • Free return shipping
  • Repair, spare parts, and replacement (at Ossila's discretion) of defective products due to faulty materials or workmanship
  • If any part is no longer available, Ossila will replace it with a functional replacement part

4.2 What the 2-year Ossila Warranty Does Not Cover

  • Normal wear and tear, including parts that might wear out over time
  • Damage from external sources such as weather, electrical outages, or power surges
  • Equipment that has been modified or serviced by anyone other than an Ossila engineer
  • Equipment that has been subjected to chemical damage through improper use
  • Equipment that has been operated outside the usage parameters stated in the User Manual associated with the equipment
  • Equipment that has been used to process any type of biological materials (viruses, bacteria, bodily fluids, etc.) due to not being able to handle items contaminated with biological waste
  • Equipment that has been rendered inoperable through accident, negligence, carelessness, misuse, contamination, improper maintenance, modification, or other external causes

5. Unpacking


5.1 Packing List

The items included in the Slot-Die Coating System are:

  • Slot-Die Coater
  • Power supply and power supply cord
  • Slot-Die Coater Head and connecting screws
  • (x5) 25 mm coating width 100 µm thick shims
  • (x5) 50 mm coating width 100 µm thick shims
  • Luer Lock to M5 thread adapter
  • PTFE tubing with Luer Lock adapters
  • Tube clip
  • (x2) LR44 batteries
  • User manual

5.2 Damage Inspection

Upon receiving the unit, examine the components for evidence of shipping damage. If damage has occurred, please contact Ossila directly for further action. The shipping comes with a shock indicator to show if the package has received an impact during transportation.

6. Safety


6.1 Warning

  • Only use the 24V power adapter and power cord supplied with the unit.
  • If using flammable or hazardous solvents, users are expected to be trained in their usage and carry out a risk assessment.
  • Keep the area around the machine clear, 1 m clearance above and 30 cm to the sides.
  • Keep clear of the machine while it is in operation.
  • If using hazardous solvents always use within a fume hood or controlled environment.
  • There are pinch points when in operation, keep hands clear of moving parts.
  • Hot plate temperatures can result in severe burns, use caution when operating at elevated temperatures. The LED will blink when the hotplate is heating up and will remain on once it has reached set temperature.
  • Do not use in an explosive atmosphere.

6.2 Use of Equipment

This Slot-Die Coater is designed to be used as instructed, which is under the following conditions:

  • Indoors in a laboratory environment (pollution degree 2).
  • Altitudes up to 2000 m.
  • Temperatures of 5°C to 40°C; maximum relative humidity of 80% up to 31°C.

The Slot-Die Coater is supplied with a 24 V DC / 6.25 A power adapter with a power cord for the country of purchase. This is in accordance with European Commission regulations and British Standards. Use of any other electrical power cables, adapters, or transformers is not recommended.

6.3 Hazard Icons

The following symbols can be found at points throughout the rest of the manual. Note and read each warning before attempting any associated operations associated with it:

Table 6.1 Hazard warning labels used in this manual.

Symbol Associated Hazard
General warning symbol General warning or caution, which accompanying text will explain
Electrical shock warning symbol Electrical shock
Pinch points warning symbol Pinch point
Hot plate warning symbol Hot surface

6.4 General Hazards

When installing or operating the Slot-Die Coater, there are several health and safety precautions that must be considered.

WARNING: Improper handling when operating or servicing this equipment can result in serious injury. Pay attention to the following hazards when operating this equipment.

Pinch points warning symbol

Pinch point and entanglement hazards are present during operation of the syringe pump and stage. As a precaution, users should avoid handling or leaning over the equipment during operation to avoid possible crushing or entanglement of hair and/or clothing. The unit weighs approximately 10 kg. Care should be taken when handling or moving the unit.

Electrical shock warning symbol

In the event of an emergency, the unit can be disabled by disconnecting the power cord from the power supply. Make sure that the power outlet for this cord is readily accessible to the operator.

Electrical shock warning symbol

Servicing should only be performed by an Ossila engineer. Any modification or alteration may damage the equipment, cause injury, or death. It will also void your equipment’s warranty.

6.5 Emergency Stop

The slot-die coater is fitted with an emergency stop button that can be pressed in the event of emergencies e.g. the trapping of objects within pinch points. When pressed, the emergency stop button cuts off the power to the system and a buzzer will turn on to indicate that the button has been pressed. The emergency stop button will remain pressed until the button is rotated clockwise and released. Once released, the system can be restarted by turning the unit off and on again using the on/off switch at the back of the unit. The emergency stop button should not be used for powering down the system after use and should only be used in emergency situations.

Ossila Slot Die Coater - red emergency stop button
Figure 6.1 The emergency stop button mounted to the front of the slot-die coater.

6.6 Tube Clip

A tube clip has been provided with the system. The clip chain attaches to the slot-die head using a simple washer. The clip itself can then be attached to any PTFE tubing that is connected to the system. This ensures that if the polypropylene connector becomes damaged during operation, the tubing is held in place and solution does not escape the system. The clip should be attached whenever the system is used.

Ossila Slot Die Coater - tube clip with chain attached to tubing to secure
Figure 6.2 The slot-die coater tube clip and chain is used to secure the tubing

6.6 Operational Safety

Any procedure involving the slot-die coater should have a suitable operating procedure, risk assessment and COSHH form(s) to ensure that the user is aware of the potential hazards inherent to the work they are undertaking. The following are safety points that should be noted by the user before any procedure is undertaken with the slot-die coater.

6.7.1 Pinch Points

Pinch points warning symbol

Both the syringe pump and the moving stage present the risk of pinch points to the user. It is recommended that any loose articles of clothing and hair are tied back and secured before using the system. In addition, we recommend that users do not place their hands near the moving sections when programs are running or when there is manual movement of the syringe pump or the stage.

6.7.2 Hot Plate

Hot plate warning symbol

The hot plate can be programmed to reach temperatures as high as 120°C. When the temperature is above 50°C, extreme care should be taken when placing and removing substrates. In addition, risk assessments should consider potential fire hazards that can occur when heating solvents to high temperatures. Many common solvents used within laboratories have a flash point below 120°C, leading to the risk of ignition. Adjust experimental parameters to reduce risk of solvent combustion.

6.7.3 Sources of Ignition

General warning symbol

Solvents can often be heated beyond their flash point, where any source of ignition can ignite the solvent. To minimize this risk users should ensure that no sources of ignition are placed close to the slot-die coating system.

6.7.4 Fire Hazard

General warning symbol

In the unlikely situation where solvents on the hotplate have ignited, the system is designed to contain any solvents either on the hotplate itself or on the baseplate below. This is to stop the spread of fire. Users are also recommended to leave at least 30 cm of space surrounding the entire system, and 1 m above the system, free from any other objects to reduce the possibility of the fire spreading.

7. Maintenance


7.1 Cleaning

Maintenance consists of periodic cleaning. The exterior of the instrument can be wiped with a clean, dry cloth to remove any oil, grease or dirt. Small amounts of solvent can be used to clean the stage and head once it has cooled to room temperature.

7.2 Repair and Service

Periodically, the rail guide and the lead screw should be lubricated with synthetic grease or oil to ensure smooth motion. Repairs or servicing not covered in this manual should not be performed. Contact Ossila if you have issues with your system.

8. Installation


The following procedure should be followed when setting up the unit for the first time.

  1. Place the unit on a solid, level surface. If necessary, the feet can be rotated to adjust their height and level the unit. Ensure the area is free from vibrations, temperature extremes and highly flammable or explosive materials. Keep the area surrounding the machine clear, with approximately 1 m clearance above the machine and around 30 cm clearance on the sides.
  2. Remove the cable ties that secure the gantry during shipping.
  3. Before plugging in the Slot-Die Coater, ensure the power switch on the unit is switched to the ‘0’ position (off).
  4. Connect the power supply connector to the Slot-Die Coater (shown in Figure 8.1).
  5. Insert one LR44 battery into each digital height gauge by removing the cap (shown in Figure 8.2).
  6. You may wish to turn the digital height gauges off when not in use to conserve battery life. This is done by pressing the ‘OFF/ON’ button. The digital height gauges are not powered or charged by the mains supply.
Plugging the power supply cable to the slot-die coater
Figure 8.1 Installation of the Slot-Die Coater by plugging in the power supply cable
Inserting the battery to the digital height gauge
Figure 8.2 Each digital height gauge should be fitted with one LR44 battery by removing the cap

9. Operating the Slot-Die Coater


9.1 Slot-Die Coater User Interface

The control panel of the Slot-Die Coater is shown in Figure 9.1. It consists of an LCD display, 11 control buttons and 2 indicators. The functions of the buttons are described in Table 9.1.

Slot-Die Coater LCD display and keypad
Figure 9.1 Slot-Die Coater LCD display and keypad

Table 9.1. Operational buttons and their associated functions

Button Name Function
Manual Mode button Manual Enter Manual Mode where the syringe driver and the slot-die stage can be moved
Program Mode button Program Enter Program Mode where saved programs can be selected and/or edited
Settings Mode button Settings Enter Settings Mode, where syringe properties can be defined, and hotplate temperature offsets can be added
Up button Up Navigating Up through menus; increasing selected values by 1; increasing unit size
Down button Down Navigating Down through menus; decreasing selected values by 1; decreasing unit size
Right button Right Navigating Right through menus, changing current program or step
Left button Left Navigating Left through menus, changing current program or step
OK button OK Press to select, edit, or accept changes
Stop button Stop Stop current running program
Start button Start Run currently selected program
Return button Return Return the stage to the home position

9.2 Program Operation

9.2.1 Turning the Unit on

  1. Turn the Ossila Slot-Die Coater power switch ON (position ‘1’). The bootup screen will show.
Bootup screen for Slot-Die Coater
  1. After the bootup, reset the stage to its ‘home’ position by pressing the “OK” button. This will move the stage to the furthest back point.
Popup message asking to confirm to reset stage to 'home' position
  1. Whilst the stage is moving to the ‘home’ position, the following message will be shown.
Message showing 'homing...'
  1. Once the system is at the ‘home’ position, the Program Mode page will be prompted.
Program Mode page

9.2.2 Settings Mode

The Settings Mode allows the user to input parameters related to the hotplate operation, syringe properties and stage homing. Edit mode can be entered by pressing “OK” on the required line. Entering edit mode on any parameter will turn the text of the parameter red.

  1. Press “S” to enter Settings Mode.
Settings mode page
    1. To switch the hotplate ON, navigate to the ‘Hotplate’ line and press “OK” to switch ON the hotplate. The ‘Heater’ LED will blink ON/OFF whilst the hotplate is heating and remain ON when it reaches the set temperature. You can switch OFF the hotplate by pressing “OK” again.
Hot plate warning symbol

Note: The Hotplate icon on the screen will blink RED while the hotplate is switched ON.

Settings mode page with hotplate icon blinking
  1. The hotplate temperature is set by navigating to the ‘Hotplate temp’ line and pressing “OK” to edit the value. To navigate between the digits, press the “Left” or “Right” buttons. To change the value of the selected digit, press the “Up” or “Down” buttons. Press “OK” again to exit the edit mode. The maximum set value allowed is 120°C.
Settings mode - select hotplate temperature
    1. The surface temperature of the hotplate may differ slightly from the displayed reading. To set the exact temperature value on the surface, a temperature offset can be applied by navigating to the ‘Temp offset’ line and pressing “OK” to edit. You can set the temperature offset by ±10 °C. To change the sign for ‘Temp offset’, navigate to the sign and press “Up” or “Down” to change it.

Note: An external temperature sensor is required to measure the surface temperature (not supplied). The displayed temperature has the offset applied and therefore will appear higher than the set point temperature when a positive offset is applied.

Settings mode - select offset temperature
    1. To change the syringe size, navigate to the ‘Syringe size’ line and press “OK” to enter edit mode. To change to different sizes of the syringe, press “Left” or “Right” to scroll between the pre-set sizes. Press “OK” again to exit the edit mode.

Note: The selected syringe size is displayed in the upper right corner within Program Mode.

Settings mode - select syringe size
    1. A custom syringe size can be entered by selecting ‘Cust’, which allows the syringe diameter to be manually entered.

Note: If the diameter value is not set, a warning will appear on the screen to notify the user.

Settings mode - selecting a custom syringe size
    1. The stage position is tracked across the slot-die coater operation. The user allows to set new HOME position for the system during current operation. To set the new stage home position, navigate to the ‘Stage Home’ line and press “OK” to edit. Press “Return” to set the new Home position based on the stage’s current position. Press “OK” again to exit the edit mode

Note: To change the stage position manually, go to Manual Mode.

Settings mode - selecting a new home location for the stage

9.2.3 Manual Mode

Manual Mode allows direct control over the syringe pump and stage positions. Entering edit mode on any parameter will turn the text of the parameter red.

Pinch points warning symbol

WARNING: Pinch points and entanglement

The rotation of the lead screw/coupling and the movement of the plunger pusher present entanglement and pinch hazards. Care should be taken when the system is running.

  1. To enter Manual Mode, press “M” located at the top left-hand side of the screen. The stage is pre-selected in Manual Mode. Press “Up” to select Stage (if not already selected).
Enter manual mode for stage
  1. The stage has pre-set speed values of 0.062 mm/s, 0.250 mm/s, 0.625 mm/s and 1.250 mm/s. To change the speed, press “OK” to choose the desired speed for Manual Mode.
Manual mode - select the speed of the stage
  1. To move the stage position manually, press “Left” or “Right” while ‘Stage’ is highlighted. The current position display will be updated automatically.
Manual mode - move the stage using the left and right buttons
  1. Press “Down” to select the ‘Syringe’
Enter manual mode for syringe
  1. The manual dispense rate of the syringe is calculated based on the selected syringe size in Settings Mode. Press “OK” to cycle through preprogramed values.
Manual mode - select the dispense rate of the syringe
  1. To dispense the solution manually, press “Left” or “Right” to move the syringe plunger position. The volume of solution dispensed will be automatically calculated and displayed.
Manual mode - use the left and right arrows to dispense the solution

9.2.4 Program Mode

Program Mode allows the user to set up a coating process by defining several parameters. Press the button to enter Program Mode. Entering edit mode on any parameter will turn the text of the parameter red.

  1. The unit can store up to 20 programs in memory with up to 50 steps in each. The current program can be changed by navigating to ‘Program’ with the “Up” button. Press “OK” to enter edit mode and press “Up” or “Down” to change the program number. Press “OK” to exit edit mode. Program number can also be changed using “Left” or “Right” without entering edit mode.
Enter Program mode - select a program number
  1. To change the number of steps in the program, navigate to steps line and press “OK” to edit the value. Press “Up” or “Down” to change the value. Press “OK” to exit edit mode.
Program mode - select the number of steps
  1. The size of syringe that has been selected in the Settings Mode appears in the top right corner. This value can be edited from the Settings Mode (see Section 9.2.2).
Program mode - the size of syringe is in the top right corner
  1. To change individual step parameter values, navigate to the ‘Step’ line. Press “OK” to enter edit mode and press “Up” or “Down” to change the value. Press “OK” again to exit edit mode. You can press “Left” or “Right” to change which step number is selected when not in edit mode.
Program mode - select a step to edit
    1. The coating length, coating speed and dispense rate can be set for each step. To edit the coating length, navigate to the ‘Coating length’ line and press “OK” to edit. The digit cursor will appear under the number.

If the coating length is set above the maximum length allowed (100 mm), a warning will appear to notify the user. The system will automatically calculate the remaining allowed length and set it in the current step.

Program mode - edit the coating length Warning message - maximum coating length exceeded
  1. To change the Coating Speed for the current step, navigate to the ‘Coating speed’ line and press “OK” to edit. The maximum coating speed allow is 50 mm/s. Coating speeds will round to the nearest value that the stepper motor can achieve.
Program mode - edit the coating speed
  1. To change the Dispense Rate for the current step, navigate to the ‘Dispense rate’ line and press “OK” to edit.
Program mode - edit the dispense rate
  1. If the dispense rate is set above the maximum allowed rate of the syringe, a warning will appear on the screen. Press “OK” to continue, and the system will autocorrect the rate to the maximum allowed rate value for the selected syringe size.
Warning message - maximum dispense rate exceeded
    1. To include the delay in the current step, navigate to the Stage delay and press “OK” to enter edit mode. The digit cursor will appear under the number. Users can navigate between the digits by pressing “Left” or “Right” buttons. To change the value of the selected digit, press “Up” or “Down” buttons. Press “OK” again to exit the edit mode.

Note: The stage delay is used to delay the coating at the beginning of the step but allow the syringe to still dispense at the set rate.

Program mode - edit the stage delay time

9.2.5 Assembly and Installation of the Slot-Die Head

The slot-die head can be assembled and installed while the unit is powered down.

  1. Make sure that the stainless-steel heads and are free of dirt or dust before assembling, or there may be defects within the coating. The head should be disassembled and cleaned after each use.
Clean heads, screws and shims.
  1. Select a shim with appropriate width for the substrate you wish to coat. Add the required number of shims to get the gap thickness required. Each shim is 100 μm thick.
Select an appropriate shim
  1. Clamp the shims between the two halves of the slot-die head and using the four shorter corner screws to clamp the slot-die head together. The screws should go through the half of the head with the socket for the Luer lock adapter first.
Clamping the shims
  1. If the micrometers are in contact with the gantry (top), retract them by turning anti-clockwise until they are no longer in contact (bottom).
Micrometers in contact with gantry Micrometers not in contact with gantry
  1. Place the slot-die head flush against both surfaces of the mounting bracket. Using the two longer bolt-on screws, attach the slot-die head to the slot-die system via the two gantry threaded holes. The side of the head with the socket for the Luer lock adapter should face outwards.
Attach the slot-die head to the system via the two gantry threaded holes.
  1. Place the Luer Lock adapter through the washer at the end of the safety clip. Attach the stainless-steel Luer lock adapter to the slot-die head. When not attached to the tubing, the safety clip chain should be kept off the stage to prevent it dragging during levelling.
Attach the stainless-steel Luer lock adapter to the slot-die head.

9.2.6 Levelling the Stage

The digital height gauges used to level the stage have a resolution of 1 µm. It is not possible to level the stage to this accuracy. Recommended levelling parameters are given in the procedure below. If substrate heating is required, the hotplate temperature should be set, thehotplate turned on and the stage allowed to reach the set point temperature before levelling the stage.

  1. Zero height gauges relative to the head:
  • In Manual Mode, use the “Right” button, move the stage so that the gauge rollers are no longer touching the top surface.
  • Turn the digital height gauges on by pressing ‘OFF/ON’ and set them to zero by pressing ‘Zero’.
Move the stage so that the gauge rollers are no longer in contact with the stage
  1. Level the stage across the width:
  • Using the “Left” button, move the stage so that the gauge rollers are on the top surface of the stage.
  • Using the left and right adjustment thumbscrews at the back of the stage, level the digital height gauges so that the readings on both dials are within 50 µm of each other. Press the ‘Zero’ button on both digital height gauges so they both read zero.
Gauge roller is in conatc with the top surface of the stage
  1. Level the stage across the length:
  • Using the “Left” button, move the stage so that the gauge rollers are now situated at the front end of the stage.
  • Using the front thumbscrew, adjust the height of the front end of the stage until the digital height gauges read close to zero on both sides.
  • The difference between either side should be no more than 50 µm.
Levelling the digital gauges
  1. The stage should already be at or close to the stage home position. To ensure this is the case return the stage to the stage home position by pressing the “Return” button. To increase the accuracy of the levelling, repeat steps 2 and 3.
Adjusting the front thumbscrew under the stage

9.2.7 Installing the Syringe

  1. There are two sets of holes on the plunger pusher to accommodate different sized syringes. The height of the plunger clip can be adjusted by changing which set of holes the securing screws pass through. The upper pair of holes can be used for large syringes, and the lower pair for small syringes.
Plunger pusher with two sets of holes for different sized syringes
  1. Fill your syringe with the desired quantity of solution. Ensure air bubbles are expelled from the syringe.
Solution filled syringe with no air bubbles
  1. Remove the barrel clamp by loosening the wing nut. Place the syringe in the syringe holder.
Removing the barrel clamp - undoing the wing nut.
  1. In Manual Mode, ensure ‘Syringe’ is highlighted and change the position of the plunger pusher by pressing the “Left” or “Right” buttons leaving sufficient space between the flange clip and the plunger clip to attach the syringe. Loosen the screws on the flange clip and the plunger clip as much as possible and insert syringe. The plunger clip can be moved vertically to better fit the syringe.
Attach the syringe using the clips
  1. Replace the barrel clamp and secure with the wingnut, then tighten the wingnut screws on the flange clip and the plunger clip until the syringe is secure.
Replace the barrel clamp and secure with the wingnut
  1. Connect the female end of the PTFE dispensing tube to the syringe
Female end of the PTFE dispensing tube connected to the syringe
  1. Connect the male end of the PTFE dispensing tube to the Luer Lock on the slot-die head and connect the safety clip to the tubing.
Male end of the PTFE dispensing tube connected to the Luer Lock on the slot-die head with safety clip attacehd to the tubing
  1. Pre-load the slot-die head. Using Manual Mode, move the plunger to push solution through the PTFE tubing until it reaches the head.
Slot-die head preloaded with solution.

9.2.8 Aligning the Slot-Die Head to the Substrate

If substrate heating is required, the hotplate temperature should be set, the hotplate turned on and the stage allowed to reach the set point temperature before aligning the substrate (see Section 9.2.2:Settings Mode for hotplate operation instructions). There is a slight expansion of the stage when heated which may affect the alignment and the readings on the digital height gauges.

Hot plate warning symbol

WARNING: Hot Surface

The hotplate is hot when heated and contact with skin can cause burns. Care should be taken when the system is running.

  1. Zero the digital height gauges to the top of the substrate.
    1. First place the substrate on the stage with the side which will be coated first closest to the front of the unit.
    2. Lower the gantry with both the micrometers until there is no longer a visible gap between the head and the substrate. The head should then be slowly lowered a few microns at a time either side, whilst sliding the substrate side to side. When the movement of the substrate becomes hindered, slowly raise the head a few microns at a time until the substrate is free to move.
    3. Repeat for the back of the substrate. Return to the front of the substrate and zero the digital height gauges.
Head and substrate in contact with no visible gap
  1. Set the gap height. Slowly raise the slotdie head using the micrometers, alternating between them in small steps, until the height gauges show the required gap (see Section 10.1).
Slot-die height gauges showing the required gap

9.2.9 Forming a Meniscus

Substrate with a meniscus formed on it from the head

Before coating, a meniscus of solution should be formed across the width of the substrate by dispensing a small amount of solution in the Manual Mode. The slowest dispense rate should be used to avoid dispensing too much solution onto the substrate, which can cause defects. Solution should be pumped until a small amount comes out of the head and forms a meniscus on the substrate surface.Alternatively, a program step can be used to perform this automatically.

9.2.10 Running a Program

Pinch points warning symbol

WARNING: Pinch points and entanglement

The rotation of the lead screw/coupling and the movement of the plunger pusher present entanglement and pinch hazards. Care should be taken when the system is running.

  1. Once the required parameters have been set in Program Mode, and both the slot-die head and syringe have been installed (see Sections 9.2.5 and 9.2.7 respectively), the program can be run by pressing the “Start” button. A green progress bar will appear showing the overall progress.
Program in progress - green bar with 5% completed

Note: If the stage delay is set in the program, the stage delay icon will appear blinking next to the elapsed time until delay time is up.

If the coating speed has not been set for all off the program steps, a warning will appear to notify the user. Running will be aborted until the speed is set.

Stage delay icon
  1. You can start coating at any stage position by positioning the stage in Manual Mode. However, the position is tracked so that it will not exceed the maximum travel distance of 100 mm. Where the total coating length plus the initial stage position exceeds this maximum travel distance, a warning will appear. The stage position should be put closer to the default home position (see Section 9.2.1: Turning the Unit On), or the coating length should be reduced.
Warning message - Distance travel exceeded, please reset to HOME

10. The Coating Process


General warning symbol

WARNING: Volatile solvents

When using volatile solvents, place the slot-die coater within a fume hood or controlled environment (e.g. a glovebox).

To use the slot-die coater, a general start-up procedure should be followed before coating should begin. There are several stages to this:

  1. Installing the slot-die head (Section 9.2.5)
  2. Setting the hotplate temperature (Section 9.2.2)
  3. Levelling the stage (Section 9.2.6)
  4. Installing the syringe (Section 9.2.7)
  5. Aligning the slot-die head with the substrate (Section 9.2.8)
  6. Forming a meniscus (Section 9.2.9)
  7. Setting the coating parameters & running the program (Section 9.2.10)

10.1 Gap Height

The gap between the slot-die head and the substrate is important to coat a defect-free film. For an indepth explanation of this please refer to Ossila’s “Slot-Die Coating: Guide to Troubleshooting Defects”.

To know the minimum gap height for coating a stable film you must first know what wet film thickness you are wanting to coat. If you are working from a dry film, you must begin by calculating the percentage volume of solids in solution. This can be done if the mass of the liquid, the mass of the solid, the density of the liquid, and the density of the solid are all known.

Formula to calculate percentage volume of solids in solution

The needed wet film thickness (twet) can then be calculated from final desired dry film thickness (tdry):

Formula to calculate the wet film thickness

As an initial number to work with, the viscous model approximation can be used. For this gap height (h) should be less than double the wet film thickness:

Viscous model approximation to calculate the gap height

It should be noted that the gap height above is only true for solutions with capillary numbers greater than approximately 0.1 to 0.25. For low capillary number solutions, where the viscosity or the speed of the stage is low, the minimum gap height is controlled by the equation below, where 𝐶𝑎 is the capillary number. This means higher gap heights can be used for low viscosity solutions.

Calculating the gap height for solutions with a low capillary number

10.2 Worked Example

For this example, a fluorescent dye in 1,1,2,2-Tetrachloroethane (TCE) was used, at a concentration of 20 mg/mL.

  1. The slot-die head was first assembled as described in Section 9.2.5. A single shim with an outlet width of 2.5 cm was used.
  2. The hotplate temperature was set at 80°C and the heater turned on (see Section 9.2.2).
Placing a shim onto the head
  1. Once the stage had reached its set point temperature, it was levelled following the instructions in Section 9.2.6 to a levelness of 50 µm i.e. the maximum absolute value seen on either digital height gauge was <50 µm across the length of the stage.
  2. A solution of dye in TCE (20 mg/mL) was prepared and filtered using a 0.45 µm PVDF (hydrophobic) syringe filter to ensure that no contaminants were present that can cause defects in the final film. A 5 mL syringe was filled with the solution and installed on the slot-die coater according to Section 9.2.7.
Filling a syringe with solution and connected it to the slot-die coater
  1. The slot-die head was lowered onto the substrate surface and retracted to give a gap of 100 µm. Experimentation to optimize the gap for a specific solution and substrate combination is strongly recommended.
Height gauges showing the retracted head height
  1. The coating parameters were programmed as described in Section 9.2.4 and theprogram run.
Slot-die dispensing solution onto a substrate
  1. The coated film is shown and achieved a film thickness of ~80 nm. Note that edge defects at the start and end of coating can be minimised by use of ‘sacrificial substrates’ before and after the main substrate wishing to be coated.
Coated substrate in a pink coloured solution
  1. The film shown above used a stage speed of 14 mm/s with a 4 µL/s flow rate.
Program running in progress - green bar showing 56% completed

11. Slot-Die Coater Troubleshooting


Table 11.1. Troubleshooting guidelines for the Ossila Slot-Die Coater

Problem Possible Cause Action
No power/display The power switch on the unit is in the OFF position Check the connection and ensure the power is turned ON
The power supply may not be connected properly Ensure the unit is firmly plugged in to the power supply and the plug is firmly connected to both the adapter and the working power socket
The fuse on the rear panel has blown Ensure the unit is unplugged. Check the fuse on the rear panel. If it has blown, replace with a suitably rated 5A slow blow fuse
The power supply adapter has a fault Contact Ossila for a replacement power supply adapter
No obvious cause If all the above causes have been considered, there may be a fault on the control board. Please contact Ossila for information
Motor Stalled (Syringe Pump) Syringe has hit first safety switch There is not enough solution in the syringe and the moving part of the pump has hit the safety switch. Load more solution into the syringe so the plunger is further back and try again The safety switch is triggered
Crash Warning The secondary safety switch has accidentally been triggered Switch the unit off and on again
The plunger pusher is triggering the secondary safety switch Rotate the lead screw by hand to move the plunger pusher closer to the centre of travel
Internal fault in the secondary safety switch If all the above has been considered there may be a fault with the secondary safety switch; contact Ossila for more information

Accessories

Compatible Substrates

Related Processing Equipment

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