spotlight on silicones

7/28/2019 Spotlight on Silicones

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T E C H S P O T L I G H T

Spotlight on Silicones

Master Bond Inc. 154 Hobart Street, Hackensack, NJ 07601 USA

Phone +1.201.343.8983 | Fax +1.201.343.2132 | WhitePaper@masterbond.

Silicone adhesives deliver outstandingflexibility and high temperature

resistance in demanding applications


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Master Bond Inc. | TEL: +1 (201) 343-8983 | www.masterbod.com | [email protected]

Spotliht o SilicoesSilicoe adhesives deliver outstadi flexibilit ad hihtemperature resistace i demadi applicatios.

Choosi the riht adhesive for the iteded applicatio

ivolves more tha readi a few specificatios o a data

sheet. Istead, adhesive selectio is perhaps best viewed as

both a art ad a sciece, where selecti the best formula

for the job ivolves balaci ma properties. For example,

bod streth, flexibilit, temperature resistace, ease ofapplicatio, ad thermal coductivit are just a few of the

ma qualities to cosider whe selecti a adhesive.

The importace of each of these qualities ca be thouht

of o a cotiuum, where certai properties are of critical

importace to the applicatio ad other properties are of

lesser cocer.

Here we will take a look at silicoe adhesive sstems,

whose mai streth lies i their uique combiatio of

flexibilit, hih temperature resistace, ad more specialized

eieeri properties.

Sloe Teholoy Overvew

Silicoe adhesives are available as both oe ad two-part

sstems for use i bodi, seali, coati, potti, ad

ecapsulatio applicatios. Oe-part liquid ad paste

sstems are the easiest to use because the require o

mixi. Also kow as room temperature vulcaizi

compouds (RTVs), the cure b usi moisture available

i the eviromet. I cotrast, two-part sstems cure b

usi a polmerizatio reactio that takes place with the

additio of a curi aet. I eeral, two-part sstems ca

cure i thicker sectios tha oe-part sstems, which ma

be required i certai applicatios. Other useful varieties

of silicoe adhesives cure upo exposure to ultraviolet

(UV) liht, electro beam (EB) radiatio, or sliht cotact

pressure, all useful methods i applicatios where excessive

heat eeratio is a cocer.

Silicoe adhesives have several importat performace

characteristics that distiuish them from other adhesive

families. Overall, users ca rel o silicoes to create bods

that withstad hih temperatures (as hih as 600F for

certai rades), sta flexible eve after curi, ad resist

both chemicals ad water. Silicoe sstems also feature

impressive electrical properties ad ma be formulated to

be isulative with hih dielectric streth, or coversel,

electricall coductive. Althouh some oe-part silicoes

release corrosive etities such as acetic acid, special

ocorrosive formulas are available ad are especiall

well suited for electroics applicatios. For example,these specialized silicoe adhesives are frequetl used

as coformal coatis for electroic circuit boards ad for

seali cables ad sesors i appliaces ad electroics.

Withi the broad classificatio of silicoe adhesives are

specific product tpes that feature uique advataes. To

make the best selectio, it is wise to discuss applicatio

details with our adhesives supplier at the earliest

opportuit.

MasterSil 415 is a one-part silicone whose superior

transparency makes it well suited for optical and electronic

display applications.


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Oe-Part Spealty Ahesves

Oe-part silicoe adhesives, sealats, ad coatis are ofte

used i optical ad electrical applicatios for assembl ad

repair tasks. Withi the oe-compoet famil of silicoe

sstems are a wide variet of specialized products offeri

various features. All products are evirometall friedl

ad free of both solvets ad diluets, eas to appl, ad

provide superior flexibilit alo with hih temperature

resistace. The are well suited for stro adhesio to lass,

plastics, metals, rubbers, ad other substrates. Amo

their chief beefits is ease of use: The cure at ambiet

temperatures without the eed for additioal curi aetsad are available with user-friedl applicators.

Beod these commo features, specialized product rades

offer optical trasparec ad resistace to vibratio, shock,

ehaced heat, ad corrosio. Other oe-part silicoes are

desied to withstad extreme humidit, provide electrical

isulatio, or coduct heat ad electricit, amo other

applicatio-specific qualities. Certai rades are certified to

meet militar stadards (MIL Specs) ad UL requiremets for

flame retardace.

To uderstad just how versatile oe-part silicoe sstemsca be, its helpful to take a closer look at some idividual

products. As oe example, cosider the widel specified

MasterSil 705TC, a eas to use, thermall coductive,

electricall isolati, hih-performace silicoe emploed i

bodi, seali, ad coati applicatios. It comes as a

off-white, ocorrosive colored paste ad readil cures at

ambiet temperatures usi ol atmospheric moisture. It is

especiall well suited for thermall coductive applicatios

where the eed to rework the assembl ma be importat.

Aother oe-part silicoe used for bodi, seali, ad

coati is MasterSil 415, which features hih trasparec

ad is especiall useful i optical ad displa applicatios.

This eas-to-use paste ca be applied to vertical surfaces

without sai or rui, ad cures to a flexible, rubber

solid whe exposed to moisture i the air. Setup time is jus

8 to 12 miutes at 75F. Whats more, MasterSil 415 ca be

used over a extesive temperature rae of -185 to 400

ad is especiall had where low temperature reliabilit is

of critical importace to the applicatio. This formula also

withstads vibratio, shock, impact, exposure to moisture

ad other weather coditios, ad is FDA compliat.

Two-Part Spealty Sloes

Two-part silicoes, also called addition curing systems,

emplo a combiatio of a silicoe polmer plus a catalst

to iitiate the cure. Althouh these two-part sstems are

ot quite as eas to use as oe-part silicoes, the offer

several advataes compared to their simpler couterparts

especiall i productio eviromets. Because a catalst

is required to iitiate the cure rather tha ambiet

moisture two-part silicoes have o problems with sectio

thickess. Therefore, the are well suited for applicatios

such as potti, ecapsulatio, ad lare castis. Aother

advatae: The release o reactio bproducts, so the

ca be used i closed eviromets. Because their cure

ca be accelerated with heat, some sstems ca be treated

with a fast, partial heat cure to eable a quick setup of the

adhesive, after which the work piece is allowed to fiish

curi at room temperature off the productio lie.

SILICOnE ADHESIVES SUITnUMEROUS InDUSTRIES

Meal Bodi of catheters ad other medical

devices

Trasportato Seali askets ad eies

Eletro Potti ad heat sik attachmet, board

coati

Lht LED assembl

Applae Seali cables ad sesors

Prt Assembli compoets used i

commercial priters

Mltary Bodi, seali, coati, ad formed-i-

place askets

Assembly Attachi compoets to larer sstems

MEETIng MIL SPECS

Special formulatios of oe-part silicoes meet the

striet requiremets for militar applicatios. These

formulas require o mixi, cure at room temperature,

ad feature superior electrical isulatio properties ad

exceptioal durabilit.

MasterSil 709 is a oe-part, fast curi, silicoe

elastomer compoud used for bodi, seali,

coati, ad formed-i-place askets. It is

ocorrosive, flowable, bods to a rae of surfaces

ad substrates, ad works i temperatures from -75 to

400F ad meets MIL-A-46146.

MasterSil 710, a ocorrosive oe-part paste, cures

rapidl with a tack-free setti time of just 7 to 12

miutes at 75F. It is used for bodi, seali, coati,

ad formed-i-place askets ad meets MIL-A-46146A

Tpe 1.


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Due to their outstadi flexibilit, two-part silicoes

feature stress-relievi capabilities over a wide temperature

rae ad provide excellet resistace to vibratio, shock,

corrosio, ad heat. The offer stro adhesio to lass,

plastics, metals, rubbers, ad other substrates. Withi

the two-part silicoe adhesives famil, specific product

formulatios feature resistace to humidit ad temperature

extremes, superior flexibilit, electrical isulatio, ad

thermal ad electrical coductivit. Certai two-part sstems

are approved for use i specific idustries, such as thosecertified to meet USP Class VI for biocompatibilit.

Despite these advataes, its importat to ote that certai

substaces ad substrates ma ihibit the curi of these

two-part sstems. Users must be aware of materials i the

applicatio ad cure area that miht cause this ihibitio.

For example, it is ver importat to avoid cotamiatio

from other silicoes that are cured usi metallic salts,

chloriated rubber compouds, PVC plasticizers, amies,

sulfur-cotaii materials, ad butl elastomers.

For further information on this article, for answers to any

adhesives applications questions, or for information on

any Master Bond products, please contact our technical

experts at Tel: +1 (201) 343-8983.

SPEciALizEd SiLicOnES AT A gLAncE

MasterSl 711

What it is: Exceptioall fast-setti, hih-performace,

ocorrosive silicoe rubber

Why use it: Cures i 3 to 5 miutes; widel used i

maufacturi ad repair applicatios

MasterSl 773

What it is: Ultra-low-viscosit silicoe coformal coati

material

Why use it: Eas applicatio b sprai, brushi, dippi

or flow coati; excellet resistace to humidit ad heat

MasterSl 803

What it is: Uique, ocorrosive idustrial silicoe featuri

ehaced hih ad low temperature serviceabilitWhy use it: Works i widel rai temperatures, from

-180 to 500F; achieves hih bod streth

MasterSl 705

What it is: Traslucet, ocorrosive silicoe well suited fo

hih-performace bodi, seali, coati, ad formed-i

place askets

Why use it: Cures at room temperature with excellet

electrical isulatio properties; hihl flexible, resists shock

ad vibratio; works over exteded temperature rae

MasterSl 705Tc

What it is: Thermall coductive, electricall isolati, eas

to-use silicoe for hih-performace bodi, seali, ad

coati

Why use it: nocorrosive, cures at room temperature; well

suited for applicatios requiri flexibilit ad resistace to

hih temperatures

STREngTH VERSUS COnDUCTIVITy

I the vast majorit of electroics applicatios, the

trade-off betwee streth ad coductivit is ot

a issue. I fact, eve whe filled with thermall

coductive additives, silicoes still offer more tha

adequate bod streth to withstad the miimal

forces ecoutered b most power-dissipati

compoets. As a example, potted compoetsma eed to withstad certai stresses duri

maufacturi ad while i use, but the are rarel

subjected to the hih forces that characterize a true

structural adhesive bod.

Thermal silicoe adhesives actuall perform double-

dut: The help maae heat, ad the also bod

compoets to create electroic assemblies. Similarl,

thermal potti compouds improve the heat trasfer

of the compoets the ecapsulate, ad the also

serve to protect those same compoets from shock,

vibratio, ad other evirometal hazards.

spotlight on silicones

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