Description
QSil 563 silicone potting compound is a two-part, 100% solids addition cure silicone from CHT, made for potting and encapsulating electronics that need thermal conductivity and a UL 94 V-0 flame rating. The cured material is hard with a low modulus, and CHT describes it as readily repairable. Made in the USA. Potting means filling an enclosure with liquid silicone that cures around the components, which protects them from moisture, shock, and vibration and gives heat a path out.
Key Product Details
| Property | Value |
|---|---|
| Chemistry | Two-part addition cure (platinum cure) silicone, 100% solids |
| Mix Ratio | 1:1 by weight |
| Color | Part A white, Part B yellow, mixed material yellow |
| Viscosity | Part A 4,000 cps, Part B 5,200 cps, mixed 4,600 cps |
| Specific Gravity | Part A 2.07, Part B 2.13 |
| Gel Time at 25 °C (77 °F) | 140 minutes |
| Cure Conditions for Listed Properties | 15 minutes at 150 °C (302 °F) |
| Hardness | 46 Shore A |
| Tensile Strength | 120 psi (0.83 N/mm²) |
| Elongation | 55% |
| Thermal Conductivity | ~0.88 W/m-K (hot wire method) |
| Useful Temperature Range | -55 to 204 °C (-67 to 399 °F) |
| Dielectric Strength | 460 V/mil |
| Dielectric Constant | 4.57 at 1,000 Hz |
| Dissipation Factor | 0.007 |
| Volume Resistivity | 6.52 x 1013 ohm-cm |
| Flame Rating | UL 94 V-0 at 3.0 mm |
| UL File Number | QMFZ2.E205830 |
| Shelf Life | Best used within 24 months from date of manufacture |
| Storage | Original unopened container, not above 38 °C (100 °F) |
| Country of Manufacture | USA |
Performance in Production
- The 1:1 ratio is by weight. Part A and Part B have slightly different specific gravities, so weigh each side on a scale instead of measuring by volume.
- Use Part A and Part B from the same lot number, as the TDS directs.
- Gel time is the point where the mix turns solid or semi-solid, and it runs 140 minutes at 25 °C. Plan the pour well inside that window and test with your own batch size.
- Air trapped during mixing should be pulled out under vacuum. Machine-mixed material does not normally need de-airing.
- At about 0.88 W/m-K, the cured silicone gives heat a path out of the potted assembly. With 100% solids and no solvent added, there is no solvent to flash off during cure.
- 46 Shore A with 55% elongation gives a firm cured material that stays a low modulus silicone. CHT calls it readily repairable, which matters when a potted assembly may need service.
- The UL 94 V-0 rating is listed at 3.0 mm. Check your potting depth against the UL file before you specify it.
- The cured properties above were measured after 15 minutes at 150 °C. CHT lists QSil 563 as an RTV grade but does not publish a room temperature full cure time, so confirm your cure schedule on a test part before production.
Common Applications
- Potting electronic assemblies and control modules that need heat moved away from components
- Encapsulating circuit boards where a UL 94 V-0 flame rating is required
- Power supply and transformer potting
- LED driver and lighting module potting
- Protecting electronics in industrial equipment from moisture, shock, and vibration
- Potted assemblies that may need repair or service later
Available Sizes
| Package | Kit Contents | Mixed Total | SKU |
|---|---|---|---|
| 2 Kg Quart Kit | 1 Kg Part A / 1 Kg Part B | 2 Kg (4.4 lb) | QTM-QSIL563A/B-4LBK |
| 10 Kg Gallon Kit | 5 Kg Part A / 5 Kg Part B | 10 Kg (22 lb) | QTM-QSIL563A/B-20LBK |
| 44 Kg Pail Kit | 22 Kg Part A / 22 Kg Part B | 44 Kg (97 lb) | QTM-QSIL563A/B-100LBK |
| 440 Kg Drum Kit | 220 Kg Part A / 220 Kg Part B | 440 Kg (970 lb) | QTM-QSIL563A/B-1000LBK |
SKUs are unchanged from the earlier 4 lb, 20 lb, 100 lb, and 1000 lb kits, so existing reorders use the same item numbers.
Related Products
- CHT QSil 553: UL 94 V-0, thermally conductive, black, 1:1 mix
- CHT QSil 556: UL 94 V-0, low viscosity, room temperature cure, black, 1:1 mix
- CHT QSil 573: thermally conductive, light gray, 1:1 mix
- All encapsulants and potting compounds
How Potting With QSil 563 Works
The steps below follow the CHT technical data sheet.
- Confirm Part A and Part B carry the same lot number.
- Mix Part A and Part B thoroughly before combining them.
- Combine the two parts at 1:1 by weight. By hand, weigh both parts into a clean plastic or metal container about three times the volume of the material and mix. With automatic equipment, use a system that mixes at 1:1 by weight.
- De-air hand-mixed material under vacuum at 29 inches of mercury. The material expands during the process, so intermittent evacuation may be needed.
- Pour or dispense into the assembly before the mix reaches gel at 140 minutes (25 °C).
- Let it cure. CHT publishes cured properties after 15 minutes at 150 °C, so confirm your own cure schedule on a test part.
The TDS does not list adhesion to specific housing materials or a primer requirement. Call us before specifying QSil 563 where the cured silicone also has to bond to the enclosure.
Frequently Asked Questions
What is QSil 563 used for?
QSil 563 is used to pot and encapsulate electronic assemblies that need a thermally conductive, flame-rated silicone. Potting silicone, silicone potting compound, and silicone encapsulant all describe the same type of product. QSil 563 is a two-part addition cure system from CHT.
What is the mix ratio for QSil 563?
The mix ratio is 1:1 by weight. Weigh Part A and Part B on a scale and use matching lot numbers. Measure by weight, since the two parts have slightly different specific gravities.
Is QSil 563 UL 94 V-0 rated?
Yes. QSil 563 carries a UL 94 V-0 rating at 3.0 mm under UL file number QMFZ2.E205830. The rating is listed at that thickness, so check your design against the UL file.
How thermally conductive is QSil 563?
QSil 563 has a thermal conductivity of about 0.88 W/m-K, measured by the hot wire method. That is the published figure for the cured material.
Does QSil 563 need a primer?
The TDS does not list adhesion data or a primer requirement for QSil 563. If the cured silicone has to bond to your housing, call us at (800) 220-1966 and test on your actual parts before production.
What is the shelf life of QSil 563?
QSil 563 is best used within 24 months from the date of manufacture. Store it in the original unopened container at no more than 38 °C (100 °F). Material past the date on the label may still be usable, and CHT advises checking the properties you need before you use it.
Is QSil 563 made in the USA?
Yes. QSil 563 is made in the USA. CHT USA runs its manufacturing facility in Richmond, Virginia.
What sizes does QSil 563 come in?
QSil 563 comes in four two-part kits: 2 Kg, 10 Kg, 44 Kg, and 440 Kg mixed total. CHT now supplies these in kilogram sizes in place of the earlier 4 lb, 20 lb, 100 lb, and 1000 lb kits, so older purchase orders may still show the lb sizes.
Questions on fit for your potting application? Call (800) 220-1966 or email [email protected].
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