FAQ: “I Have a Difficult Adhesive Mix Ratio. Can Appli-Tec Help?”

Mixing a two-part adhesive manually.

Mix ratio is the amount of resin and the amount of hardener needed to obtain the desired properties of the adhesive once it cures.

The impact of mix ratio on adhesive performance is critical: if not mixed correctly, an adhesive can be resin rich or hardener rich – impacting everything from cure rate, lap shear and viscosity to electrical, thermal, and outgassing properties.

Appli-Tec provides some of its materials as two-part kits, with Mix Ratio called out on the TDS. For example, the mix ratio for Appli-Tec’s 5336 Epoxy is 100 for Part A and 6 for Part B.

Appli-Tec 5336 epoxy mix ratio

While you can mix 5336 Epoxy in-house, 100 to 6 is a tough ratio to get exactly right.

Even with a calibrated scale, extra drops or not enough drops of the curing agent will result in a decline of performance: Hardness, Glass Transition Temperature, and Low Outgassing properties will be negatively impacted.

Other challenges: Vacuum degassing, instrument calibration, adhesive waste

Once mixed, the adhesive must be vacuumed degassed to remove air and prevent voids. The problems associated with voids include:

• Pitted surface (pictured)
• Reduced bond strength
• Decreased environmental resistance
• Lower thermal and electrical conductivity

Cured adhesive with voids (left) and properly degassed (right)

Testing ensures the material matches its specifications for Tg, shore hardness, and viscosity. While testing is relatively easy, a non-calibrated instrument results in data inaccuracy and/or production delays until the instrument has been professionally calibrated.

Engineers who opt to manually apply adhesives usually work with very small amounts: e.g. one, three or five grams.

The challenge here is potential material waste: If you’ve mixed 10 or 20 grams of adhesive, you have a lot left over. You’re now responsible for dealing with a complicated chemical waste stream.

The solution: Pre-Mixed and Frozen Adhesives by Appli-Tec

The advantages of using Pre-Mixed and Frozen (PMF) adhesives are many and include:

• The cost of maintaining a mix room, including instrument calibration
• Significant uptime – you simply thaw a syringe and go
• Less complicated waste stream
• Defect-free adhesives, every time

Most important, we handle all the mixing, degassing, and testing for you – as well as relieving you of the worry and stress of dealing with difficult mix ratios.

We can also custom formulate your adhesive to solve your unique application challenge or provide recommendations for discontinued materials.

To learn more, complete our RFQ form or send us an email. Our expert team will advise you on the best adhesive material as well as provide options for dealing with tough mix ratios.

Alisha Adams is the Research and Development Lead for Appli-Tec. Her expertise includes formulating epoxy and acrylate adhesives for the electronics market.

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