www.bergquistcompany.comAll statements, technical information and recommendations herein are based on tests we believe to be reliable, andTHE FOLLOWING IS MADE IN LIEU OF ALL WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING THE IMPLIEDWARRANTIES OF MARKETABILITY AND FITNESS FOR PURPOSE. Sellers’ and manufacturers’ only obligation shall be toreplace such quantity of the product proved to be defective. Before using, user shall determine the suitability of the productfor its intended use, and the user assumes all risks and liability whatsoever in connection therewith. NEITHER SELLER NORMANUFACTURER SHALL BE LIABLE EITHER IN TORT OR IN CONTRACT FOR ANY LOSS OR DAMAGE, DIRECT,INCIDENTAL, OR CONSEQUENTIAL, INCLUDING LOSS OF PROFITS OR REVENUE ARISING OUT OF THE USE ORTHE INABILITY TO USE A PRODUCT. No statement, purchase order or recommendations by seller or purchaser notcontained herein shall have any force or effect unless in an agreement signed by the officers of the seller and manufacturer.

APN_LBEA1805_0914

Liqui-Bond®Thermally Conductive Liquid Adhesive Materials - Epoxy

Liqui-Bond® EA Application Note

Liqui-Bond® EALiqui-Bond® EA is a family of epoxy based, liquid dispensable,thermally conductive adhesive materials. These materials aredispensed as a liquid onto the target surface. As the components are assembled, the material will wet-out to theadjacent surfaces, filling even the smallest gaps and air voids.Liqui-Bond® EA is ideally suited for applications where a structural bond is needed and can be utilized in a wide range of power supply, telecom, digital, lighting and automotive applications.

Liqui-Bond® EA Key Performance BenefitsLow Pre-Cured Modulus: Minimal Stress During Assembly

Because Liqui-Bond® EA is dispensed and wet-out in its liquidstate, the material will induce very low stress on componentsduring the assembly process. Liqui-Bond® EA can be utilized tointerface the most fragile and delicate devices where the use of a standard pad or tape may cause device damage.Excellent Conformability to Intricate Geometries

Liqui-Bond® EA materials are able to conform to intricatetopographies, including multi-level surfaces. Due to its increasedpre-cured mobility, Liqui-Bond® EA can fill small air voids,crevices, and holes where a pad or tape cannot, reducing overall thermal resistance to the heat generating device and its heat sink. Lower Material Usage

Liqui-Bond® EA can be supplied in large containers for use withhigh-volume automated dispensing. Automated dispensing allowsfor precise placement of the material with minimal materialwaste and greatly reduces the application time of the material.

Material CharacteristicsThixotropic Behavior

Thixotropic is defined as the measure of a material’s internalcohesive characteristics (material consistency) combined withits target adhesive characteristics (ability to adhere to the target surface). This characteristic is intended to provide anindicator of how the material will behave in the assemblyprocess, after dispensing and prior to cure.Viscosity Dependence on Shear Rate

Due to the above-mentioned thixotropic characteristics ofmost Liqui-Bond® EA materials, special consideration should

be given to the test method(s) used to determine viscosity ofthese materials. The material viscosity is dependent on shearrate, different measurement equipment testing under differentshear rates will produce varied results. When comparingapparent viscosities of multiple materials, it is important toensure that the data was generated using the same testmethod (and therefore the same shear rate).Working Time

Liqui-Bond® EA is a two-part material that will not experiencepremature crosslinking during storage, handling and dispensing.Once the material is mixed, the material begins to crosslink orcure. The rate of cure depends upon the surface area to massratio of the adhesive and the thermal mass of the assemblyitself. The curing reaction of the Liqui-Bond® EA generatesheat and self-heating of the adhesive can occur during cure. Working time is when the cure reaction rate begins toincrease significantly and assembly operations should be completed prior to this timeframe. Liqui-Bond® EA will start to cure once the material is mixed. Working time is heavilydependent on temperature. Working time will decrease withtemperatures above 25°C and increase with temperaturesbelow 25°C.

The Bergquist Company - Asian HeadquartersHong KongPh: 852-2690-9296Fax: 852-2690-3408

The Bergquist Company - European HeadquartersNetherlandsPhone: 31-35-5380684Fax: 31-35-5380295

The Bergquist Company -North American Headquarters18930 West 78th StreetChanhassen, MN 55317Phone: 800-347-4572Fax: 952-835-4156

Cure Time

Liqui-Bond® EA materials cure relatively quickly at room temperature. Typical cure schedules are noted in the productdata sheets. Curing at higher temperatures will result in significantly faster reaction and a slightly stronger bond.Thermal and dielectric properties are not affected by the cure schedule or cure state.

Fixturing During Cure

A minimum of 5psi fixturing pressure throughout the curecycle is recommended to prevent the components from shifting during cure. The duration of the fixturing variesdepending on the cure profile. At room temperature, the fixture can typically be removed after two hours. Bond Line Thickness

To obtain optimal adhesive strength, a final bond line thicknessof <10 mil (250 μm) is recommended. Above this thickness,the Liqui-Bond® EA will provide thermal transfer but will havea lower bond strength.

Usage Recommendations

Containers

Sample Sizes: Bergquist typically supplies two-part systemsamples in 50cc cartridges.Order Sizes: Bergquist offers a wide range of container sizesfor its products. TwinDual cartridges are available in 50cc,200cc, and 400cc sizes. Liqui-Bond® EA is also availablein1200cc (Qty 2, 600cc cartridges) and 7-gallon (Qty 2, 3.5-gallon pails) kit sizes for volume production. Other special and custom container sizes are available upon request. Bergquist does not recommend repackaging of material from one container size to another due to the risk of air entrainment and contamination.

Operating Temperature Ranges

For the epoxy based Liqui-Bond® EA, the continuous useoperating temperature range is typically from –40°C to 125°C(-40°F to 257°F) for extended periods of time, except whenotherwise noted on product specific data sheets. Note however, that at both the low and high end of the temperature spectrum, the behavior of the materials and theperformance in specific applications can require additionalattention to ensure suitability for the conditions. Dispensing

Manual: Bergquist offers applicator guns and static mixingequipment for products supplied in dual cartridge form. Theuse of industry standard applicator guns and static mixing nozzles are an inexpensive means for dispensing product forsampling and low volume production. Manual hand triggeredguns are available for 50cc, 200cc, and 400cc cartridge sizes.Pneumatic operated guns are also available for 200cc and400cc cartridge sizes. Automated: Bergquist Liqui-Bond® EA supplied in high volumecontainer kits can be dispensed via automated dispensingequipment for high-speed in-line manufacturing. Bergquist containers are designed for use in dispensing units for quickand easy loading and unloading. High volume container sizesare 1200cc, and 7-gallon kits. Automated Dispensing Equipment Alliances

Bergquist has aligned with several experienced automated dispensing equipment vendors to further assist our customers in creating an optimized dispensing process. For informationregarding dispensing equipment, contact your local Bergquistrepresentative.Mixing Tolerances

Two-part materials must be mixed to a 1-to-1 ratio by volume within a +/-5% tolerance to ensure proper curedhardness, adhesive strength, working time and cure time. Iflight colored streaks or marbling are present in the materialafter mixing, then the mixing was inadequate. Continue mixinguntil the color is consistent with no streaks. In order to ensureconsistent material characteristics and performance, Bergquisttwo-part systems are always to be used with matching part Aand B lot numbers. Static Mixing Nozzles

Disposable plastic static mixing nozzles are used to mix partsA and B together at the desired ratio. Static mixers can beattached to the ends of cartridges or mounted on automateddispensing equipment. They are reliable, accurate and inexpensive to replace after extended down times. Unlessotherwise indicated, mixing nozzles with a minimum of 21mixing elements are recommended to achieve proper mixing.

When first using new two part containers, Bergquist recommends purging sufficient material through a static mixeruntil a uniform color is noticed, to ensure complete mixing.Material should not sit idle in the mixing tube longer than thestated working time of the material, otherwise material willbegin to thicken and eventually cure in the mixer. If this occursthe mixer should be disposed of and replaced with a newmixer. As temperature increases, working time decreases.Therefore, if the ambient temperature at the point of dispensing is greater than 25°C, there may be a need tochange out the mixing nozzle more frequently than the statedworking time would indicate. The actual frequency of mixerchange-out should be determined by the customer, based ontheir specific environmental operating conditions.Surface Preparation

All surfaces should be thoroughly cleaned and degreased withsolvents such as acetone, isopropyl alcohol (IPA), mineral spirits, naphtha, or methyl ethyl ketone (MEK). Allow the surface to dry completely prior to applying the material.Depending on the surface, certain cleaning techniques maygive better results than others. Customers should determinethe best cleaning technique for their application. De-Airing

Air entrainment in the material should be avoided wheneverpossible. Proper design and use of dispensing equipment canhelp to minimize the introduction of air. The absence of airwill optimize thermal and electrical performance and minimizethe probability for corona, arcing, and electrical failure in high-voltage applications. Bergquist takes every precaution tominimize the presence of air in its liquid material.Rework

The possibility to rework an assembly after cure is applicationspecific. Typically rework is not recommended.Chemical Exposure

Bergquist cured liquid adhesives are generally very resistant tofuels, solvents, oils, acid, and alkali solutions. The exception isstrong oxidizing agents, such as concentrated sulfuric acid solutions, which can decompose the adhesive systems. Solventsand fuels may cause the elastomers to swell and become softunder heavy exposure. However, when the adhesives areallowed to dry out they will return to their original size andhardness. Note however, that Liqui-Bond® EA is designed forintermittent exposures only. Bergquist recommends that customers test the material in the application under actual service conditions to confirm compatibility. Compatibility

While silicones will not inhibit the cure of Liqui-Bond® EA ,they can prevent wet out of the substrate, which can lead to a

weak bond. All surfaces to be bonded should be cured andsilicone-free. Additionally, the Liqui-Bond® EA product linecontains components that can prevent addition cure of silicones and the two types of materials should be kept out of contact with one another.If there are potential compatibility questions or concerns, it isrecommended that a test be run to determine suitability in agiven application. Incomplete surface cure at the interfacebetween the questioned substrate and Bergquist material indicates an incompatibility. Shipping and Storage

Unless otherwise indicated on product data sheets, two-partLiqui-Bond® EA materials should be stored in the original sealedcontainer at 5-30°C and <60% relative humidity. If stored atreduced temperatures, materials should be placed at room temperature and allowed to stabilize prior to use. Unless otherwise noted, all cartridges and tubes should be stored inBergquist defined packaging with the nozzle end down to helpminimize air voids within the material and help minimize potential liquid migration around the end caps/plugs.Separation/Settling

Under normal storage conditions at 25°C there will be minimal settling of most Liqui-Bond® EA materials during theshelf life. However, some amount of settling (typically up to5% by weight) is inherent with highly filled materials and cannot be avoided. When dispensing from a new cartridge orpail, it is recommended to purge sufficient material until a uniform consistency is achieved. The B side of the material may also take on some surface yellow discoloration where the material is exposed to humidair. This discoloration is typical and will not influence the performance of the Liqui-Bond® EA adhesive.Shelf Life

Bergquist two-part Liqui-Bond® EA material has a defined shelflife measured from the date of manufacture, when stored inthe original sealed container in a climate controlled environment at 5-30°C and <60% relative humidity. Shelf lifefor specific Bergquist materials is identified on product datasheets. Short periods of time above the recommended storage temperature, such as during shipping, have not beenshown to affect the material characteristics. Bergquist does notadvocate using material beyond the recommended shelf lifeand is unable to recertify material that has expired. In order toensure timely use of product, Bergquist recommends a first-expire-first-out (FEFO) inventory system. Bergquist is notable to ensure the full stated shelf life from the time of customer receipt. Bergquist will ship these products with noless than 80% of the stated shelf life remaining.

Liqui-Bond® EA 1805 at Various Cure TemperaturesLap Shear Strength, Alum to Alum

Adh

esiv

e St

reng

th(p

si)

1200

1000

800

600

400

200

0

Cure Time (Minutes)

150°C Cure

1 2 4 8 16 32 64 128 256 512

125°C Cure

100°C Cure

75°C Cure

50°C Cure

25°C Cure

Cure Temp (°C)150

125

100

75

50

25

5

10

20

30

60

600

Cure Time (min)

Cure Time

Liqui-Bond® EA materials cure relatively quickly at room temperature. Typical cure schedules are noted in the productdata sheets. Curing at higher temperatures will result in significantly faster reaction and a slightly stronger bond.Thermal and dielectric properties are not affected by the cure schedule or cure state.

Fixturing During Cure

A minimum of 5psi fixturing pressure throughout the curecycle is recommended to prevent the components from shifting during cure. The duration of the fixturing variesdepending on the cure profile. At room temperature, the fixture can typically be removed after two hours. Bond Line Thickness

To obtain optimal adhesive strength, a final bond line thicknessof <10 mil (250 μm) is recommended. Above this thickness,the Liqui-Bond® EA will provide thermal transfer but will havea lower bond strength.

Usage Recommendations

Containers

Sample Sizes: Bergquist typically supplies two-part systemsamples in 50cc cartridges.Order Sizes: Bergquist offers a wide range of container sizesfor its products. TwinDual cartridges are available in 50cc,200cc, and 400cc sizes. Liqui-Bond® EA is also availablein1200cc (Qty 2, 600cc cartridges) and 7-gallon (Qty 2, 3.5-gallon pails) kit sizes for volume production. Other special and custom container sizes are available upon request. Bergquist does not recommend repackaging of material from one container size to another due to the risk of air entrainment and contamination.

Operating Temperature Ranges

For the epoxy based Liqui-Bond® EA, the continuous useoperating temperature range is typically from –40°C to 125°C(-40°F to 257°F) for extended periods of time, except whenotherwise noted on product specific data sheets. Note however, that at both the low and high end of the temperature spectrum, the behavior of the materials and theperformance in specific applications can require additionalattention to ensure suitability for the conditions. Dispensing

Manual: Bergquist offers applicator guns and static mixingequipment for products supplied in dual cartridge form. Theuse of industry standard applicator guns and static mixing nozzles are an inexpensive means for dispensing product forsampling and low volume production. Manual hand triggeredguns are available for 50cc, 200cc, and 400cc cartridge sizes.Pneumatic operated guns are also available for 200cc and400cc cartridge sizes. Automated: Bergquist Liqui-Bond® EA supplied in high volumecontainer kits can be dispensed via automated dispensingequipment for high-speed in-line manufacturing. Bergquist containers are designed for use in dispensing units for quickand easy loading and unloading. High volume container sizesare 1200cc, and 7-gallon kits. Automated Dispensing Equipment Alliances

Bergquist has aligned with several experienced automated dispensing equipment vendors to further assist our customers in creating an optimized dispensing process. For informationregarding dispensing equipment, contact your local Bergquistrepresentative.Mixing Tolerances

Two-part materials must be mixed to a 1-to-1 ratio by volume within a +/-5% tolerance to ensure proper curedhardness, adhesive strength, working time and cure time. Iflight colored streaks or marbling are present in the materialafter mixing, then the mixing was inadequate. Continue mixinguntil the color is consistent with no streaks. In order to ensureconsistent material characteristics and performance, Bergquisttwo-part systems are always to be used with matching part Aand B lot numbers. Static Mixing Nozzles

Disposable plastic static mixing nozzles are used to mix partsA and B together at the desired ratio. Static mixers can beattached to the ends of cartridges or mounted on automateddispensing equipment. They are reliable, accurate and inexpensive to replace after extended down times. Unlessotherwise indicated, mixing nozzles with a minimum of 21mixing elements are recommended to achieve proper mixing.

When first using new two part containers, Bergquist recommends purging sufficient material through a static mixeruntil a uniform color is noticed, to ensure complete mixing.Material should not sit idle in the mixing tube longer than thestated working time of the material, otherwise material willbegin to thicken and eventually cure in the mixer. If this occursthe mixer should be disposed of and replaced with a newmixer. As temperature increases, working time decreases.Therefore, if the ambient temperature at the point of dispensing is greater than 25°C, there may be a need tochange out the mixing nozzle more frequently than the statedworking time would indicate. The actual frequency of mixerchange-out should be determined by the customer, based ontheir specific environmental operating conditions.Surface Preparation

All surfaces should be thoroughly cleaned and degreased withsolvents such as acetone, isopropyl alcohol (IPA), mineral spirits, naphtha, or methyl ethyl ketone (MEK). Allow the surface to dry completely prior to applying the material.Depending on the surface, certain cleaning techniques maygive better results than others. Customers should determinethe best cleaning technique for their application. De-Airing

Air entrainment in the material should be avoided wheneverpossible. Proper design and use of dispensing equipment canhelp to minimize the introduction of air. The absence of airwill optimize thermal and electrical performance and minimizethe probability for corona, arcing, and electrical failure in high-voltage applications. Bergquist takes every precaution tominimize the presence of air in its liquid material.Rework

The possibility to rework an assembly after cure is applicationspecific. Typically rework is not recommended.Chemical Exposure

Bergquist cured liquid adhesives are generally very resistant tofuels, solvents, oils, acid, and alkali solutions. The exception isstrong oxidizing agents, such as concentrated sulfuric acid solutions, which can decompose the adhesive systems. Solventsand fuels may cause the elastomers to swell and become softunder heavy exposure. However, when the adhesives areallowed to dry out they will return to their original size andhardness. Note however, that Liqui-Bond® EA is designed forintermittent exposures only. Bergquist recommends that customers test the material in the application under actual service conditions to confirm compatibility. Compatibility

While silicones will not inhibit the cure of Liqui-Bond® EA ,they can prevent wet out of the substrate, which can lead to a

weak bond. All surfaces to be bonded should be cured andsilicone-free. Additionally, the Liqui-Bond® EA product linecontains components that can prevent addition cure of silicones and the two types of materials should be kept out of contact with one another.If there are potential compatibility questions or concerns, it isrecommended that a test be run to determine suitability in agiven application. Incomplete surface cure at the interfacebetween the questioned substrate and Bergquist material indicates an incompatibility. Shipping and Storage

Unless otherwise indicated on product data sheets, two-partLiqui-Bond® EA materials should be stored in the original sealedcontainer at 5-30°C and <60% relative humidity. If stored atreduced temperatures, materials should be placed at room temperature and allowed to stabilize prior to use. Unless otherwise noted, all cartridges and tubes should be stored inBergquist defined packaging with the nozzle end down to helpminimize air voids within the material and help minimize potential liquid migration around the end caps/plugs.Separation/Settling

Under normal storage conditions at 25°C there will be minimal settling of most Liqui-Bond® EA materials during theshelf life. However, some amount of settling (typically up to5% by weight) is inherent with highly filled materials and cannot be avoided. When dispensing from a new cartridge orpail, it is recommended to purge sufficient material until a uniform consistency is achieved. The B side of the material may also take on some surface yellow discoloration where the material is exposed to humidair. This discoloration is typical and will not influence the performance of the Liqui-Bond® EA adhesive.Shelf Life

Bergquist two-part Liqui-Bond® EA material has a defined shelflife measured from the date of manufacture, when stored inthe original sealed container in a climate controlled environment at 5-30°C and <60% relative humidity. Shelf lifefor specific Bergquist materials is identified on product datasheets. Short periods of time above the recommended storage temperature, such as during shipping, have not beenshown to affect the material characteristics. Bergquist does notadvocate using material beyond the recommended shelf lifeand is unable to recertify material that has expired. In order toensure timely use of product, Bergquist recommends a first-expire-first-out (FEFO) inventory system. Bergquist is notable to ensure the full stated shelf life from the time of customer receipt. Bergquist will ship these products with noless than 80% of the stated shelf life remaining.

Liqui-Bond® EA 1805 at Various Cure TemperaturesLap Shear Strength, Alum to Alum

Adh

esiv

e St

reng

th(p

si)

1200

1000

800

600

400

200

0

Cure Time (Minutes)

150°C Cure

1 2 4 8 16 32 64 128 256 512

125°C Cure

100°C Cure

75°C Cure

50°C Cure

25°C Cure

Cure Temp (°C)150

125

100

75

50

25

5

10

20

30

60

600

Cure Time (min)

www.bergquistcompany.comAll statements, technical information and recommendations herein are based on tests we believe to be reliable, andTHE FOLLOWING IS MADE IN LIEU OF ALL WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING THE IMPLIEDWARRANTIES OF MARKETABILITY AND FITNESS FOR PURPOSE. Sellers’ and manufacturers’ only obligation shall be toreplace such quantity of the product proved to be defective. Before using, user shall determine the suitability of the productfor its intended use, and the user assumes all risks and liability whatsoever in connection therewith. NEITHER SELLER NORMANUFACTURER SHALL BE LIABLE EITHER IN TORT OR IN CONTRACT FOR ANY LOSS OR DAMAGE, DIRECT,INCIDENTAL, OR CONSEQUENTIAL, INCLUDING LOSS OF PROFITS OR REVENUE ARISING OUT OF THE USE ORTHE INABILITY TO USE A PRODUCT. No statement, purchase order or recommendations by seller or purchaser notcontained herein shall have any force or effect unless in an agreement signed by the officers of the seller and manufacturer.

APN_LBEA1805_0914

Liqui-Bond®Thermally Conductive Liquid Adhesive Materials - Epoxy

Liqui-Bond® EA Application Note

Liqui-Bond® EALiqui-Bond® EA is a family of epoxy based, liquid dispensable,thermally conductive adhesive materials. These materials aredispensed as a liquid onto the target surface. As the components are assembled, the material will wet-out to theadjacent surfaces, filling even the smallest gaps and air voids.Liqui-Bond® EA is ideally suited for applications where a structural bond is needed and can be utilized in a wide range of power supply, telecom, digital, lighting and automotive applications.

Liqui-Bond® EA Key Performance BenefitsLow Pre-Cured Modulus: Minimal Stress During Assembly

Because Liqui-Bond® EA is dispensed and wet-out in its liquidstate, the material will induce very low stress on componentsduring the assembly process. Liqui-Bond® EA can be utilized tointerface the most fragile and delicate devices where the use of a standard pad or tape may cause device damage.Excellent Conformability to Intricate Geometries

Liqui-Bond® EA materials are able to conform to intricatetopographies, including multi-level surfaces. Due to its increasedpre-cured mobility, Liqui-Bond® EA can fill small air voids,crevices, and holes where a pad or tape cannot, reducing overall thermal resistance to the heat generating device and its heat sink. Lower Material Usage

Liqui-Bond® EA can be supplied in large containers for use withhigh-volume automated dispensing. Automated dispensing allowsfor precise placement of the material with minimal materialwaste and greatly reduces the application time of the material.

Material CharacteristicsThixotropic Behavior

Thixotropic is defined as the measure of a material’s internalcohesive characteristics (material consistency) combined withits target adhesive characteristics (ability to adhere to the target surface). This characteristic is intended to provide anindicator of how the material will behave in the assemblyprocess, after dispensing and prior to cure.Viscosity Dependence on Shear Rate

Due to the above-mentioned thixotropic characteristics ofmost Liqui-Bond® EA materials, special consideration should

be given to the test method(s) used to determine viscosity ofthese materials. The material viscosity is dependent on shearrate, different measurement equipment testing under differentshear rates will produce varied results. When comparingapparent viscosities of multiple materials, it is important toensure that the data was generated using the same testmethod (and therefore the same shear rate).Working Time

Liqui-Bond® EA is a two-part material that will not experiencepremature crosslinking during storage, handling and dispensing.Once the material is mixed, the material begins to crosslink orcure. The rate of cure depends upon the surface area to massratio of the adhesive and the thermal mass of the assemblyitself. The curing reaction of the Liqui-Bond® EA generatesheat and self-heating of the adhesive can occur during cure. Working time is when the cure reaction rate begins toincrease significantly and assembly operations should be completed prior to this timeframe. Liqui-Bond® EA will start to cure once the material is mixed. Working time is heavilydependent on temperature. Working time will decrease withtemperatures above 25°C and increase with temperaturesbelow 25°C.

The Bergquist Company - Asian HeadquartersHong KongPh: 852-2690-9296Fax: 852-2690-3408

The Bergquist Company - European HeadquartersNetherlandsPhone: 31-35-5380684Fax: 31-35-5380295

The Bergquist Company -North American Headquarters18930 West 78th StreetChanhassen, MN 55317Phone: 800-347-4572Fax: 952-835-4156