OPTOLINQ TMC-688H | Transparent Mold Compound

Harmonization Code : 3907.30.00.90 | Polyacetals, other polyethers and epoxide resins, in primary forms; polycarbonates, alkyd resins, polyallyl esters and other polyesters, in primary forms : Epoxide resins : Other

OPTOLINQ TMC-688H | Transparent Mold Compound

Main features

Low Lumen Decay
High Glass Transition Temperature
Superior moldability and reliability

Product Description

OPTOLINQ TMC-688H is an optically clear epoxy molding compound specifically designed for the encapsulation of applications that require low lumen decay and low stress molding. Its high glass transition temperature ensures good performance in high-temperature environments.

OPTOLINQ TMC-688H offers excellent moisture resistance, maintaining performance even in high temperature and humidity conditions. TMC-688H stands out with its superior moldability and reliability, ensuring good quality and precision in optoelectronic device molding.

A variant of TMC-688H is also available with a lower modulus associated with a reduced glass transition temperature.

OPTOLINQ TMC-688H comes in different sizes to meet various mold design requirements. Contact us for custom sizes or other specific requirements.

Key Features

High IR Transparency: Ensures superior infrared light transmission for optimal device performance.
Low Moisture Absorption & Excellent Moisture Resistance: Effectively prevents moisture ingress, safeguarding long-term reliability.
Reliable Under Harsh Conditions: Maintains consistent performance in environments with elevated temperature and humidity.
High Adhesion & Low Stress: Provides strong, durable bonding with minimal internal stress, reducing the risk of delamination or cracking.

Typical Applications

LED indicative devices
In/outdoor Display
Backlight Source
White light products

Versions Available

Standard low modulus optical molding compound - TMC-688L
High glass transition temperature - TMC-688H

Alternative to: XX-830 Series, XX-831 series

Specifications
Additional Information

Technical Specifications

General Properties

Specific Gravity

Specific Gravity
Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume.

For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless.

1.25

Physical Properties

Spiral Flow @ 175°C

170 ±70 cm

Mechanical Properties

Flexural Modulus
Flexural Modulus @ 25°C	3.55 N/mm2

Flexural Strength
Flexural Strength @ 25°C Flexural Strength @ 25°C Flexural strength, also known as modulus of rupture, or bend strength, or transverse rupture strength is a material property, defined as the stress in a material just before it yields in a flexure test. This is the flexural strength tested at Room Temperature, 25°C	120 N/mm2

Molded Shrinkage

1.5 %

Thermal Properties

Coefficient of Thermal Expansion (CTE) Coefficient of Thermal Expansion (CTE) CTE (Coefficient of thermal expansion) is a material property that is indicative of the extent to which a material expands with a change in temperature. This can be a change in length, area or volume, depending on the material. Knowing the CTE of the layers is helpful in analyzing stresses that might occur when a system consists of an adhesive plus some other solid component.
Coefficient of Thermal Expansion (CTE) , α1 Coefficient of Thermal Expansion (CTE) , α1 CTE α1 (alpha 1) is the slope of the Coefficient of thermal expansion in a temperature range below the Glass transition temperature (Tg). It explains how much a material will expand until it reaches Tg.	60±20 ppm/°C
Coefficient of Thermal Expansion (CTE), α2 Coefficient of Thermal Expansion (CTE), α2 CTE α2 (alpha 2) is the slope of the Coefficient of thermal expansion in a temperature range above the Glass transition temperature (Tg). It explains the extent to which a material will expand after it passes Tg.	180±20 ppm/°C

Gel Time Gel Time Gel time is the time it takes for a material to reach such a high viscosity (gel like) that it is no longer workable. It is usually measured for different temperature conditions and even though it does not refer to full cure it is advisable to never move or manipulate the material after it reached its gel time since it can lose its desired end properties.
Gel time @ 150°C	25-60 Sec

Glass Transition Temperature (Tg)

Glass Transition Temperature (Tg)
The glass transition temperature for organic adhesives is a temperature region where the polymers change from glassy and brittle to soft and rubbery. Increasing the temperature further continues the softening process as the viscosity drops too. Temperatures between the glass transition temperature and below the decomposition point of the adhesive are the best region for bonding.

The glass-transition temperature Tg of a material characterizes the range of temperatures over which this glass transition occurs.

>145 °C

Curing Conditions

Curing Schedule

Curing Schedule
Curing schedule is the time and temperature required for a mixed material to fully cure. While this applies to materials that cure with heat, there are also other materials that can be cured with UV.

Even though some materials can cure on ambient temperatures, others will require elevated temperature conditions to properly cure.

There are various curing schedules depending on the material type and application. For heat curing, the most common ones are Snap cure, Low temperature cure, Step cure and Staged cure.

Recommended cure type, schedule, time and temperature can always be found on the Technical data sheets.

Cure Time

2.5–4 min

Transfer Time

75 ±25 s

Additional Information

OPTOLINQ TMC-688H Series Technical Specifications

Property	Unit	TMC-688H	TMC-688L
Transmittance at 400 nm (1 mm)	%	>85	>85
Pellet Color	–	White	White
Specific gravity	–	1.25–1.3	1.25–1.3
Spiral flow at 150 °C	cm	170 ± 70	170 ± 70
Glass transition temperature (Tg)	°C	>145	>115
Coefficient of thermal expansion, α1	ppm/°C	60 ± 20	75 ± 25
Coefficient of thermal expansion, α2	ppm/°C	180 ± 20	190 ± 20
Gel time at 150 °C	s	25–60	25–60
Mold Shrinkage	%	<1.5	<1.5
Flexural strength	MPa	>120	>120
Flexural modulus	GPa	3.55 ± 0.25	3.05 ± 0.15

Processing Instructions

Before use, allow TMC-688H to reach room temperature (20±5 °C, 40±15% RH) for a minimum of 24 hours for larger pellets and 12 hours for smaller ones, ensuring the bag remains unopened to prevent moisture contamination.
For TMC-688H in larger sizes, preheating can be performed using standard RF equipment. Preheating must be done slowly to achieve uniform temperature.
Apply an outer releasing agent, such as silicones or fluorinated compounds, to the mold surface to facilitate easy release from the mold dies.
Prior to molding with TMC-688H or any new material, the mold should be cleaned thoroughly. To prepare the mold, the initial three shots should be cured for 5–10 minutes. After this initial preparation period, you can reduce the curing time to a level that provides sufficient hot hardness for effective release.

Storage and Handling

OPTOLINQ TMC-688H is available in pressed pellets in a wide range of sizes to meet specific customer needs. To ensure product integrity, keep it away from oxidizing materials. For long-term storage, maintain a cold environment, ideally at –10°C or lower. The shelf life under this condition is 6 months.