10 COATING, ENCAPSULATION and STAKING (ADHESIVE)
When coating or encapsulation materials are applied to glass body components, the components shall [D1D2D3] be sleeved to prevent cracking, unless the material has been selected so as not to damage the components/assembly in its service environment.
The material specification or other documented procedure shall [D1D2D3] be followed for mixing and curing. The material shall [D1D2D3] be used within the time period specified (both shelf life and pot life) or used within the time period indicated by a documented system the manufacturer has established to mark and control age-dated material.
Equipment used for measuring viscosity, mixing, applying and curing silicone material shall not [D1D2D3] be used for applying other material.
10.1 Conformal Coating <no change> 10.1.1 Application <no change>
10.1.1.1 Components Required to be Uncoated <no change>
10.1.1.2 Conformal Coating on Connectors Mating connector surfaces of printed circuit assemblies shall not [D1D2D3] be freeof
coatedwith conformal coating. Theconformalcoatingspecifiedontheassemblydrawing(s)/documentationshould,however,provide asealaroundtheperimeterofallconnector/boardinterfaceareas.
10.1.1.3 Conformal Coating on Brackets <no change> 10.1.2 Performance Requirements
10.1.2.1 Thickness <no change>
10.1.2.2 Coating Coverage <no change>
10.1.3 Conformal Coating Inspection VisualInspectionofconformalcoatingshall[A1P2D3]beperformed(seeTable11-2) andVisualinspectionofconformalcoating may be performed without magnification. Inspection for conformal coating coverage may be performed under an ultraviolet (UV) light source when using conformal coating material containing a UV tracer. Magnification up to 4X may be used for referee purposes.
10.1.4ReworkofConformalCoatingProcedureswhichdescribetheremovalandreplacementofconformalcoatingshall
[N1D2D3]bedocumentedandavailableforreview.
10.2 Encapsulation <no change> 10.2.1 Application <no change>
10.2.1.1 Encapsulant Free Surfaces <no change>
10.2.2 Performance Requirements The applied encapsulant shall [N1D2D3] be completely cured, homogeneous, and cover only those areas specified on the assembly drawing(s)/documentation. The encapsulant shall [D1D2D3] be free of bubbles, blisters, or breaks that affect the printedcircuit assembly operation or sealing properties of the encapsulant material. There shall [N1P2D3] be no visible cracks, crazing, mealing, peeling, and/or wrinkles in the encapsulant material.Minorsurfaceswirls,striations,orflowmarksarenot considereddefects.
10.2.3 Rework of Encapsulant Material <no change> 10.2.4 Encapsulant Inspection <no change>
10.3Staking(Adhesive)Thecriteriabelowshall[D1D2D3]beusedwhenstakingisrequiredandcriteriaarenotprovidedonthe drawing.
a.PlacementStakingmaterialsshallnot[P1D2D3]contactcomponentleadsealsunlessthematerialhasbeenselectedsoasnotto
damagethecomponents/assemblyinitsserviceenvironment.
b.Unsleevedaxialleadedcomponentsmountedhorizontally–Stakingmaterialshall[N1N2D3]beappliedtobothsidesofthe
component.Thelengthofthefilletsofthestakingmaterialshall[D1D2D3]extendbetween50%and100%ofthecomponentlength.
Minimumfilletheightshall[D1D2D3]be25%oftheheightofthecomponent.Formaximumfilletheight,thetopofthecomponent
shall[N1P2D3]bevisiblefortheentirelengthofthecomponentbody.
c.Unsleevedaxialleadedcomponentsmountedvertically-Aminimumoftwobeadsofstakingmaterialshall[N1D2D3] beplaced
approximatelyevenlyaroundtheperipheryofthecomponent.Foreachbead,thestakingmaterialshall[N1D2D3]contacta
minimum-25%tomaximum-100%oftheheightofthecomponentbody.Slightflowofstakingmaterialunderthecomponentbodyis
acceptableprovideditdoesnotviolate10.3a.Adhesiveshall[D1D2D3]adheretoatleast25%ofthecomponentcircumference.
d.Sleevedaxialleadedcomponents-Stakingmaterialshall[N1D2D3]beincontactwithbothend-facesofthecomponentandthe
surfaceitisbeingstakedto.Minimumfilletheightshall[N1D2D3]beatleast25%ofthecomponentheight.Maximumfilletheight
shall[P1D2D2]benogreaterthan50%ofthecomponentheight,andshall[N1D2D3]meettherequirementsof10.3.a. This clause
does not apply to sleeved glass bodied axial leaded components (see 10.3e).
e.Glassbodiedcomponents–Sleevedglassbodiedcomponentsshall[N1D2D3]befreefromstakingmaterialonanyexposedglass
surface,suchasthecomponentendface.Stakingmaterialshall[N1N2D3]beappliedtobothsidesofthecomponent.Staking
materialfilletshall[N1D2D3]extendbetween50%and100%ofthecomponentlength.Minimumfilletheightshall[D1D2D3]be
25%ofthecomponentheight.Maximumfilletheightshall[N1P2D3]allowthetopofthecomponenttobevisiblefortheentire lengthofthecomponentbody.
f.Radialleadedcomponentswhoselongestdimensionistheirheight(e.g.,CKRcapacitors,SingleIn-Line(SIP)resistornet-
works)Thestakingmaterialshall[N1D2D3]beappliedtoaminimumheightof25%toamaximumof100%ofeachindividual
Forcloselyspacedarraysconsistingofuptofourcomponentsfilletheightrequirementsforthetwoouterend-facesshall[N1D2D3] bethesameasforanindividualcomponent.Inaddition,thetopinnersurfacesshall[N1D2D3]bebondedtoeachotherfor50%of
thecomponents’width.
Forcloselyspacedarraysconsistingofmorethanfourcomponentsstakingshall[N1D2D3]beappliedinthesamemannerasarrays
uptofourcomponents,withtheadditionalrequirementthateveryotherinternalcomponentshall[N1D2D3]havetheirsidesstakedto theboardsurface.
g.Radialleadedcomponentswhoselongestdimensionistheirdiameterorlength(e.g.,TO5semiconductors,etc.).Cylindrical
componentsshall[N1D2D3]bestakedwithatleastthreebeadsofstakingmaterialplacedapproximatelyevenlyaroundtheperiphery
ofthecomponent.Foreachbead,thestakingmaterialshall[N1D2D3]contactaminimum-25%tomaximum-100%oftheheightof
thecomponentbody.Slightflowofstakingmaterialunderthecomponentbodyisacceptableprovideditdoesnotviolate10.3a.
Rectangularcomponentsshall[N1D2D3]bestakedwithabeadofstakingmaterialplacedateachcornerofthecomponent.Foreach
bead,thestakingmaterialshall[N1D2D3]contactaminimum-25%tomaximum-100%oftheheightofthecomponentbody.Slight
flowofstakingmaterialunderthecomponentbodyisacceptableprovideditdoesnotviolate10.3a. h.Fastenersidentifiedonthedrawingtobestakedshall[D1D2D3]bestakedeither:
a. Attwoplacesspacedapproximatelyoppositeofeachother,withbeadofstakingmaterialcoveringatleast25%oftheperimeter ofthefastener.
b. Withonebeadofstakingmaterialcoveringatleast50%oftheperimeterofthefastener.
10.3.1Staking
Stakingshall[D1D2D3]:
a. Becompletelycuredandhomogeneous.
b. Befreeofvoidsorbubblesthatexposecomponentconductors,bridgenoncommonconductorsand/orviolatedesignelectrical
clearance.
c. Notbridgebetweenthesubstrateandthebottomofradialleadedcomponents.Thisdoesnotapplytobondingorunderfilling
whenusedaspartofadocumentedprocess.
d. Befreeofcontamination.
e. Notnegatestressrelief.
10.3.2Staking(Inspection)Visualinspectionofstakingmaybeperformedwithoutmagnification.Magnificationfrom1.75Xto4X
maybeusedforrefereepurposes.