SQ™ is a negative tone epoxy photoresist specifically formulated for microfluidics and PDMS molding. Sensitive to Near-UV, i-line and broadband wavelengths, it is a great alternative to SU8.
SQ™ uses superior epoxies, now adapted to microfluidics, with improved optical transparency, particles and filter-ability, and lot-to-lot consistency. This makes SQ™ outperform standard SU-8 when it comes to soft-lithography.
Film thickness from 2 to 100 µm in a single coating, up to 200 µm with a double coating.
General
SQ superior photoresist for microfluidics
SQ has been developped with superior specifications to address applications as demanding as microelectronics. This SQ for microfluidics inherits from this development and shows outstanding performances when used for soft-lithography.
SQ for Microfluidics offers the following advantages:
- Superior cleanliness
- Excellent reproducibility
- Improved consistent surface energy for soft-lithography in Microfluidics
- Thourough Quality Control
- Better lot-to-lot consistency
- Fully compatible with SU-8 processes
5 types are available, for typical thicknesses as follows:
- SQ-2 for around 1 to 4 µm
- SQ-5 for around 3 to 11 µm
- SQ-10 for around 8 to 22 µm
- SQ-25 for around 11 to 48 µm
- SQ-50 for around 25 to 100 µm
Easy to switch from SU-8 epoxy photoresists
When switching to SQ, you won't have to modify your workflow: SQ shares the same protocol (see the Protocol tab).
While we advise you to use SQ Developer, a premium grade chemical, you can also use your usual SU-8 developer, or standard PGMEA.
Just like SU-8, SQ is available in different types (SQ-2 to SQ-50) depending on the aimed thickness, and in various packaging (from 100 mL to 4 x 4 L), always at a very affordable price!
5 reasons to switch from SU-8 to SQ
PLUG-N-PLAY
SQ™ is fully compatible with established SU-8 lithographic processes. Pull out SU-8 negative epoxy and plug in KemLab SQ™.
LOWER PRICING
SQ™ is designed to be competitive in the market with prices that beat the competition. Better quality for less cost.
SUPERIOR RAW MATERIALS
Start with better materials, make a better product. SQ™ uses a superior quality resin specially designed for the microelectronics industry. This superior resin manufacturing process produces a cleaner, more consistent negative epoxy photoresist with fewer particles, more transparency, and fewer microbubbles.
BETTER OPTICAL TRANSPARENCY
SQ™ resin material is visually cleaner, less yellow and more transparent resulting in improved transmission and resistance to oxidative yellowing versus SU-8.
APPLICATION-FOCUSED QUALITY CONTROL
Value-added testing was identified and implemented to benefit specific microfluidic and optical industry requirements.
PDF Datasheet
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Safety DataSheet
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Specifications
| General Properties |
| Tone |
Negative |
| Max Single Coat Thickness, µm |
100 |
| Aspect Ratio |
10:1 |
| Storage Condition / Shelf Life |
15-30°C / 1 yr |
| Mechanical Properties |
| Softening Point / Tg |
210°C |
| Young’s Modulus |
2.0 GPa |
| Coeff. of Thermal Expansion, CTE |
52 ppm/°C |
| Tensile Strength |
60 MPa |
| Thermal Conductivity |
0.2 – 0.3 W/m·K |
| Thermal Stability |
315°C |
| Electrical Properties |
| Dielectric Constant (relative), 1 GHz, 50% RH |
4.0 |
| Dielectric Loss, 1 GHz |
~0.02 |
| Dielectric Strength (V/µm) |
112 |
| Volume Resistivity (Ω·cm) |
~2.5 x 1016 |
Protocol
SUBSTRATE PREPARATION
SQ™ adheres to variety of substrates; including silicon, gold, aluminum, chromium, and copper. For maximum adhesion, substrates should be clean and dry prior to applying SQ™ photoresist.
SPINCOATING
Film thickness is targeted using the spin speed curves shown below. The coat program uses a 5 - 10 second spread cycle. Spin time at final speed is 30 seconds.
SQ Spin Speed vs. Film Thickness
SOFTBAKE
The recommended softbake for the SQ™ utilizes a two-step bake on a contact hot plate in order to minimize film stress and adhesion issues. See the table below for details.
EXPOSURE
SQ™ is designed for near UV (300-400nm) exposure wavelengths. Exposure dose will vary depending on the exposure tool set, film thickness, and process conditions. Nominal exposure doses are shown in the table below. If you know the typical lamp surface power density of your illumination device, you can use our dedicated calculator to get personalized exposure times.
POST-EXPOSURE BAKE (PEB)
Recommended PEB time is adjusted according to film thickness in order to ensure sufficient crosslinking of the resist film. A two-step PEB is recommended to reduce film stress which can lead to cracking and/or adhesion loss. See the table below for details.
DEVELOPMENT
SQ™ is designed for use with KemLab SQ™ Developer. SU-8 Developer and PGMEA can be used but with no guarantee on the optimal performances of the resist. SQ™ can be developed using immersion, puddle or spray puddle. Thicker films benefit from refreshing developer during the develop step; such as with a double puddle. Rinse developer off substrate with isopropyl alcohol (IPA) and dry. See the table below for recommended development time.
HARDBAKE
SQ™ can be hardbaked for permanent applications that would benefit from further crosslinking.
Bake at > 120°C for at least 5 minutes (hot plate). A short hardbake can fuse cracks caused by film stress. For permanent structures, temperatures above 150°C are recommended: oven bake will increase crosslinking with minimal increase in stress.
*Exposure time is given by the ratio of the given Exposure Dose value and the power density of your illumination device.
For instance, for a source with 35 mW/cm² power density, exposure time for a 2 µm thick film is 200/35 = 5.7 s.
FAQ
How is SQ different than SU-8?
SQ is a direct substitute for most applications. The epoxy resin used in SQ is originally designed and manufactured for the microelectronics industry; ensuring superior cleanliness and lot-to-lot reproducibility.
Which exposure wavelenght should I use?
SQ™ is designed for near UV (300-400nm) exposure wavelengths, including the commonly used i-line (365 nm). Nominal exposure doses are shown for broadband exposure with a 360 nm cutoff filter.
How should I store SQ negative epoxy?
The SQ resist series shows excellent resistance to temperature extremes in terms of performance and shelf life. It is recommended however that for best performance and resist life that the material be stored at room temperature.
Can I use SU-8 Developer or PGMEA with SQ?
Yes, you can use it. KemLab cannot guarantee the optimum performance of the resist with these other developers.
How do I remove SQ?
SQ is a permanent resist and very difficult to remove after cross-linking. However, it can be removed using plasma etching, laser ablation, etc.
Is there a double coat process recommendation for larger thicknesses?
Yes. See the dedicated guide here.
