Best Practices in Selecting Coatings and Pottings for Solar Panel Systems; Junction Boxes and Inverters

Size: px

Start display at page:

Download "Best Practices in Selecting Coatings and Pottings for Solar Panel Systems; Junction Boxes and Inverters"

Alaina Scott
5 years ago
Views:

1 Best Practices in Selecting Catings and Pttings fr Slar Panel Systems; Junctin Bxes and Inverters DfR Slutins, HB Fuller and Tnsan Virginia Manr Rd Ste 290, Beltsville MD

2 Intrductin The slar industry has driven slutins that result in electrnics systems that are required t perfrm in utside envirnments fr ver 25 years. This industry expectatin has resulted in slutins t prtect the electrnics frm failure that can result frm interactin with misture, and varius chemicals leading t crrsin and shrting f the systems. Ptting and encapsulatin cmpunds can impart the very high level f prtectin frm envirnmental, thermal, chemical, mechanical, and electrical cnditins that the slar applicatins demand Virginia Manr Rd Ste 290, Beltsville MD

3 Cating and Ptting Rules f Thumb The use f ptting cmpunds and thick cnfrmal catings greatly influences the failure behavir under temperature cycling Any time a material ges thrugh its glass transitin (Tg) temperature prblems tend t ccur Ptting materials can cause PCB warpage and tensile stresses n electrnic packages that greatly reduce time t failure Selectin f the crrect material fr cating r ptting is critical 9000 Virginia Manr Rd Ste 290, Beltsville MD

4 Typical Slar Envirnment Extreme ht and cld lcatins (AZ t AK) Pssible expsure t misture/humidity Large diurnal thermal cycle events (daily) Largest temp swings ccur in desert lcatins where it can reach 64C in the direct sun dwn t 23C at night (Δ41C) 9000 Virginia Manr Rd Ste 290, Beltsville MD

5 Cnfrmal Cating 9000 Virginia Manr Rd Ste 290, Beltsville MD

6 Cnfrmal Cating Optins Cnfrmal Cating Overview: Cnfrmal cating is applied t circuit cards t prvide a dielectric layer n an electrnic bard. This layer functins as a membrane between the bard and the envirnment. With this cating in place, the circuit card can withstand mre misture by increasing the surface resistance r surface insulatin resistance (SIR). With a higher SIR bard, the risk f prblems such as crss talk, electrical leakage, intermittent signal lsses, and shrting is reduced. This reductin in misture will als help t reduce metallic grwth called dendrites and crrsin r xidatin. Cnfrmal cating will als serve t shield a circuit card frm dust, dirt and pllutants that can carry misture and may be acidic r alkaline Virginia Manr Rd Ste 290, Beltsville MD

7 Summary f Cnventinal Materials 9000 Virginia Manr Rd Ste 290, Beltsville MD

8 Hw is Cnfrmal Cating Applied? The cnfrmal cating material can be applied by brushing, spraying r dipping. Or, due t the increasing cmplexities f electrnic circuit bard assemblies being designed and with the 'prcess windw' becming smaller and smaller, by selectively cating via rbt Virginia Manr Rd Ste 290, Beltsville MD

9 Inspectin Inspectin f the cating is easily accmplished using Black Light t expse the surface t be inspected. The cnfrmal cating will fluresce. Areas that are cated will lk like snw n the surface f the PWB, while uncated areas lk dark. This allws tuch up t be perfrmed t assure full cverage f the prduct. Inspectin Requirements are usually t IPC-610 fr cmmercial applicatins and MIL-I fr military Virginia Manr Rd Ste 290, Beltsville MD

10 Selecting the Right Material Selecting the apprpriate cating based n the applicatin will reduce the risk f failure. Fr instance, an acrylic cating wuld nt be the ideal chice fr an autmtive applicatin, because this cating type tends t sften (lw glass transitin temperature, Tg) with the high temperatures and expsure t misture r petrleum residues. A better chice might be a silicne cating, which has a usable perating range f -55 C t +200 C and ffers resistance t high humidity envirnments. An ultravilet (UV) cured cating may nt be the best chice if the assembly in questin has high-prfile cmpnents. Shadwing can leave uncured cating which cmprmises the reliability f the PWB. Sme cating manufacturers address this issue by adding catalysts which act as a secndary cure mechanism Virginia Manr Rd Ste 290, Beltsville MD

11 Prblems Prblem 1: Des Nt Cnsider Lw Standff Cmpnents QFN standff can be less than five mil (125 micrns) Prblem 2: Des Nt Cnsider Glass Transitin Temperature (Tg) 9000 Virginia Manr Rd Ste 290, Beltsville MD

12 CTE Mismatch/Thickness Breaking Cmpnents Primary cncern is stress due t CTE mismatch Very sensitive t thickness Similar specs in IPC2221, J-STD-001, and IPC-HDBK Virginia Manr Rd Ste 290, Beltsville MD

13 Slder Fracture Why? Dip cated assembly with BGA technlgy Passed ALT (-40C / 100C) Failing quickly in the field 9000 Virginia Manr Rd Ste 290, Beltsville MD

14 Cating Under Cmpnent Causing Lifting 9000 Virginia Manr Rd Ste 290, Beltsville MD

15 Breaking Cmpnents Glass Transitin Temperature All amrphus materials have a glass transitin temperature (Tg) Hard/Brittle Sft/Rubbery Acrylic Urethane Silicne -65C 125C 9000 Virginia Manr Rd Ste 290, Beltsville MD

16 Strage Mdulus (MPa) CTE (ppm/ C) Tg Behavir Near the glass transitin temperature (Tg), CTE changes mre rapidly than mdulus Changes in the CTE in plymers tend t be driven by changes in the free vlume Changes in mdulus tend t be driven by increases in translatinal / rtatinal mvement f the plymer chains Increases in CTE tend t initiate befre decreases in mdulus because lwer levels f energy (temperature) are required t increase free vlume cmpared t increases in mvement alng the plymer chains High stresses generated due t CTE increase befre mdulus decrease Strage Mdulus Temperature ( C) CTE 20 0 Plymer Science and Technlgy, Chapter 4: Thermal Transitins in Plymers, Rbert Obigbatr Ebewele, CRC Press, Virginia Manr Rd Ste 290, Beltsville MD

Cnfrmal Cating and N-Clean Cncerns abut applying cnfrmal cating ver n-clean flux residues Cnfrmal cating suppliers tend t nt recmmend Sme have cmpatibility dcs Residues can reduce adhesin, ptentially

17 Cnfrmal Cating and N-Clean Cncerns abut applying cnfrmal cating ver n-clean flux residues Cnfrmal cating suppliers tend t nt recmmend Sme have cmpatibility dcs Residues can reduce adhesin, ptentially resulting in delaminatin Creates micr-cndensatin cnditins; mre detrimental than n cnfrmal cating Has nt stpped the practice Current industry standards create relatively benign cnditins Allws prducts t pass qualificatin 9000 Virginia Manr Rd Ste 290, Beltsville MD

18 Ptting Materials 9000 Virginia Manr Rd Ste 290, Beltsville MD

19 Ptting Materials Very similar behavir t that f cnfrmal catings Ptting materials are als designed t prtect electrnics frm envirnmental, chemical, mechanical, thermal, and electrical cnditins that culd damage the prduct. Selectin f the wrng ptting fr yur applicatin culd result in damage frm the ptting due t unwanted stresses r heat. Thugh there are ptting materials made frm plyurethane, silicne and UV cured acrylic, mst ptting applicatins use epxy cmpunds due t their balance f mechanical, thermal, electrical and adhesin prperties 9000 Virginia Manr Rd Ste 290, Beltsville MD

20 Why Use Ptting Materials? Questins t ask yurself. Des the ptting cmpund perfrm a thermal functin? Des it need t prtect frm aggressive chemicals r misture? Des it need t prtect frm shck lads? Will the ptting see high temperatures during manufacturing? Are issues such as utgassing, crygenic peratin, r medical cmpatibility invlved? Ask the right questins during the design cycle t keep prblems t a minimum Virginia Manr Rd Ste 290, Beltsville MD

21 Knw Yur Thermal Situatin One f the mst cmmn issues with selecting the right ptting material is understanding yur thermal requirements Typically selected based n min and max temperatures Maybe OK, but des nt take ramp times and dwells int cnsideratin Failing t cnsider dwell and ramp times ften can lead t ver specifying the materials Fr example, if yu select a material with a 200C cntinuus rating, it wuld be able t withstand a shrt burst at 250C during a sldering peratin Ignring the shrt dwell time culd result in selecting a much mre expensive material than yu actually require Virginia Manr Rd Ste 290, Beltsville MD

22 The Curing Prcess Typically, manufacturers will select the ptting material with the fastest cure cycle. A risk is that the fast cure can result in a larger exthermic reactin which culd pssibly cause damage (ptential >200C) Fast cures als have the ptential fr entrapped bubbles, which can impact the materials electrical and mechanical prperties The selectin f a 1 r 2 part material als can have an impact selecting the easiest apprach may nt be the best The mre ptting material invlved the higher risk assciated with the exthermic reactin during curing especially in thicknesses greater than ¼ t ½ inch 9000 Virginia Manr Rd Ste 290, Beltsville MD

23 Think Abut the Flw and Think Small Viscsity is primary parameter Gemetry f husing r shell in relatin t the cmpnents n the PCB is als imprtant Watch fr large hrizntal surfaces when filled frm the tp, they can entrap misture r air that can affect electrnic cmpnents 9000 Virginia Manr Rd Ste 290, Beltsville MD

Ptting Ideally the CTE f the ptting shuld be as clse t the CCA as pssible Usually in the 20 t 30 ppm/ C The larger the CTE, the mre cmpliant the ptting must be t limit the stresses imparted t the CCA

24 Ptting Ideally the CTE f the ptting shuld be as clse t the CCA as pssible Usually in the 20 t 30 ppm/ C The larger the CTE, the mre cmpliant the ptting must be t limit the stresses imparted t the CCA Ptting shuld the generate hydrstatic pressure (equal n all sides) f the circuit card This prevents warping f the CCA as the ptting expands Excessive warping will greatly reduce time t failure May cause verstress failures. This may require mdificatin t the husing Husing may need t be relatively stiff 9000 Virginia Manr Rd Ste 290, Beltsville MD

25 Slder Stresses Very high stresses during cld dwell f thermal cycle COLD HOT 9000 Virginia Manr Rd Ste 290, Beltsville MD

26 Creep Strains The higher the creep strains the shrter the time t failure Unptted Ptted Excessive creep ccurring at cld temperature Mre energy required t cause cld temperature creep (mre damaging) 9000 Virginia Manr Rd Ste 290, Beltsville MD

27 Creep Strain In materials science, creep is the tendency f a slid material t slwly mve r defrm permanently under the influence f stresses. It ccurs as a result f lng term expsure t high levels f stress that are belw the yield strength f the material. Creep is mre severe in materials that are subjected t heat fr lng perids, and near melting pint. Creep always increases with temperature. The rate f this defrmatin is a functin f the material prperties, expsure time, expsure temperature and the applied structural lad. Depending n the magnitude f the applied stress and its duratin, the defrmatin may becme s large that a cmpnent can n lnger perfrm its functin fr example creep f a turbine blade will cause the blade t cntact the casing, resulting in the failure f the blade. Creep is usually f cncern t engineers and metallurgists when evaluating cmpnents that perate under high stresses r high temperatures. Creep is a defrmatin mechanism that may r may nt cnstitute a failure mde. Mderate creep in cncrete is smetimes welcmed because it relieves tensile stresses that might therwise lead t cracking. Unlike brittle fracture, creep defrmatin des nt ccur suddenly upn the applicatin f stress. Instead, strain accumulates as a result f lng-term stress. Creep is a "timedependent" defrmatin 9000 Virginia Manr Rd Ste 290, Beltsville MD

28 Ptting and Sherlck DfR has added a mdule t ur Sherlck sftware t assess the impact f the applicatin f a cating r ptting material 9000 Virginia Manr Rd Ste 290, Beltsville MD

29 Ptting and Sherlck 9000 Virginia Manr Rd Ste 290, Beltsville MD

30 Cnclusins Mechanical prperties f the ptting material Glass transitin temperature (Tg) Mdulus shuld be specified abve and belw the Tg CTE shuld be specified abve and belw the Tg The design f the husing May prvide a surface t which the ptting material can pull against when shrinking causing PCB warpage Shuld be designed t prvide as clse t a hydrstatic pressure as pssible (equal pressure n all sides) 9000 Virginia Manr Rd Ste 290, Beltsville MD

31 Electrnic Prtectin fr Junctin Bx Date:

Paul, Minnesta Glbal with direct presence

32 H.B. Fuller Cmpany Over 127 years f success as a manufacturer f specialty chemical prducts: Adhesives, sealants, catings and plymers Headquartered in St. Paul, Minnesta Glbal with direct presence in: 43 cuntries Custmers in mre than 100 natins 2014 sales f ~$2 billin Public cmpany listed n NYSE (FUL) TONSAN ADHESIVE, INC. tgether. we create

33 TONSAN Slar Sealing and Bnding Slutins Frame Sealing 1527 Silicn Sealant fr PV Mdules Cnnect the frames and the laminate; Bnd the junctin bx and the backsheet; Increase the safety and reliability f the junctin bxes; Cst reductin and efficiency imprvement. Junctin Bx Attaching 1527 Silicn Sealant fr PV Mdules Junctin Bx Ptting 1521 Ptting Cmpund fr PV Junctin Bx TONSAN ADHESIVE, INC. tgether. we create Autmatic Dispensing Machine DP-800-X220,used fr frame sealing DP-400,used fr junctin bx attaching LDP-700A,used fr junctin bx ptting

34 Sketch f J-bx Main cmpnent and functin Cver Bdy Dides Wire Cnnectr It s main functin is cnnecting and prtecting the PV mdules, cnducting the current generated by PV mdules. System cnnected by J-bx Wrking mde f dides Bypass mde (Mdule partly shaded) Nrmal mde TONSAN ADHESIVE, INC. tgether. we create

35 Applicatin Applicatin requirements Can be used in harsh envirnment; Excellent resistance t UV radiatin and aging prperty; Have reasnable heat dissipatin mde and inner cavity structure t help reduce the internal temperature and meet the electric requirements; Reliable sealing prperties. Superir insulatin and flame resistant prperties. TONSAN ADHESIVE, INC. tgether. we create

36 Slutins fr J-Bx Sealing Junctin Bx Ptting 1. Sealing Perfrmance 2. Dielectric Prperties 3. Thermal Cnductivity TONSAN ADHESIVE, INC. tgether. we create

37 Why J-bx need ptting and hw it wrks? Seal invalidatin f J-Bx withut ptting Rubber Strip aging Size tlerance Seal invalidatin Crrsin, electrical resistance increase TONSAN ADHESIVE, INC. tgether. we create

38 Why J-bx need ptting and hw it wrks? Slutins fr J-bx seal invalidatin Junctin Bx Ptting Pt a certain amunt f silicne cmpund in junctin bx. When it cured, a prtective barrier will be cnstructed. As a result, the dides and ther cmpnents inside are islated frm the external envirnment. Inner structure Ptting area TONSAN ADHESIVE, INC. tgether. we create

at break(%) Tensile strength Elngatin Tensile strength (MPa) Befre aging After DH1000 Aging time(h) Befre and

39 Why J-bx need ptting and hw it wrks? Slutins fr J-bx seal invalidatin Reliable sealing f 1521 Aging prperties f 1521 Chesive failure rate(%) Elngatin at break(%) Tensile strength Elngatin Tensile strength (MPa) Befre aging After DH1000 Aging time(h) Befre and after aging, 1521 has excellent tensile prperties and gd adhesin t PPO, TPT and PVDF, etc.. It can prvide lng-term reliable prtect fr the junctin bx. TONSAN ADHESIVE, INC. tgether. we create

40 Why J-bx need ptting and hw it wrks? Ptential insulatin failure f J-Bx withut ptting Salt spray Rain Misture Shrt circuit, Breakdwn inside utside Get an electric shck TONSAN ADHESIVE, INC. tgether. we create

41 Why J-bx need ptting and hw it wrks? Slutins fr J-Bx insulatin failure Insulatin Perfrmance f 1521 Item Unit Test result Test result after DH1000 Vlume resistivity Ω cm Breakdwn vltage KV/mm With gd insulatin prperties, TONSAN ptting material can help t reduce the ccurrence pssibility f breakdwn and electric leakage. TONSAN ADHESIVE, INC. tgether. we create

42 Why J-bx need ptting and hw it wrks? J-Bx verheating failure The wrking temperature f the bypass dides will rise fast when the ht spt phenmenn ccurs. In this cnditin, rapid heat dissipatin is very imprtant, in rder t avid fire caused by verheating. Burnt junctin bx Cause backsheet burnt Mdule cracks TONSAN ADHESIVE, INC. tgether. we create

43 Why J-bx need ptting and hw it wrks? Slutins fr J-bx verheating failure Heat dissipatin cmparisn test Withut ptting Ptting TONSAN can help t decrease the wrking temperature f dides. Thus it avids the risk f dide failure as a result f verheating. The amplitude can reach 30 TONSAN ADHESIVE, INC. tgether. we create

dissipatin; decrease the wrking temperature f the bypass dides Ptting Material Reduce the verall cst Suitable fr the

44 Why J-bx need ptting and hw it wrks? Summary With gd prperties, ur ptting materials can help t imprve the safety f J-bx. Gd adhesin and durable sealing; increase the reliability Excellent dielectric prperties, increase the safety Accelerate heat dissipatin; decrease the wrking temperature f the bypass dides Ptting Material Reduce the verall cst Suitable fr the autmated mixing and dispensing; mix mre even Years f applicatin experience, gd market acceptance TONSAN ADHESIVE, INC. tgether. we create

Mre than 200 sets machine made by TONSAN are being used

45 Autmated slutins f ptting Our ptting materials are suitable fr the autmated mixing and dispensing. Mre than 200 sets machine made by TONSAN are being used steadily and successfully. TONSAN ADHESIVE, INC. tgether. we create

46 Applicatin case Mre than150 custmers; Mre than60% market share in China. TONSAN ADHESIVE, INC. tgether. we create

Cnfrmal Cating Intrductin What is Cnfrmal Cating? Cnfrmal Catings Specially frmulated thin film materials that are applied directly t circuit bards r circuit card assemblies (CCAs).

47 Cnfrmal Cating Intrductin What is Cnfrmal Cating? Cnfrmal Catings Specially frmulated thin film materials that are applied directly t circuit bards r circuit card assemblies (CCAs). These prvide envirnmental prtectin fr the cmpnents and circuitry affixed atp these circuit cards. The material frms a dry resilient cating designed t prtect against misture, mld, dust, crrsin and ther extreme envirnmental stresses. Cnfrmal Catings Dust prf Misture prf Mld Prtectin TONSAN ADHESIVE, INC. tgether. we create

48 Cnfrmal Cating Intrductin TONSAN ADHESIVE, INC. tgether. we create

49 Why Cnfrmal Cating TONSAN ADHESIVE, INC. tgether. we create

Cnfrmal Cating Intrductin Type Acrylic Epxy Alkyd PU Silicne Applicability A B A C C Repair A D A B C Curing Speed A C B B C Mechanical Strength C A B B C Heat

50 Cnfrmal Cating Intrductin Type Acrylic Epxy Alkyd PU Silicne Applicability A B A C C Repair A D A B C Curing Speed A C B B C Mechanical Strength C A B B C Heat Resistance B B B B A Humidity Resistance A B B A C Chemical Resistance B A B A B Insulativity A B A B A A-Excellent B-Gd C-Nrmal D-Bad TONSAN ADHESIVE, INC. tgether. we create

51 Cnfrmal Cating Intrductin UV Curing Oxygen/ Humidity Slvent Evapratin Slid Cntent(%) 95~100 15~100 15~45 Curing Time(min) 10s~60s 10~60 10~60 Thickness(um) 30~120 10~80 10~35 VOC(%) 0~5 5~85 55~85 Mechanical Strength A B A Slvent Resistance A B C Insulating Prperty A B A Neutral Salt Fg,168h A A A Ht and Humid/85 85%RH, 240H A A A Heat and Cl/-40~85 A A A Heat Resistant A B(Yellwing) A A-Excellent B-Gd C-Nrmal D-Bad TONSAN ADHESIVE, INC. tgether. we create

Prduct Intrductin Prduct Descriptin Type EA6103 EA6106 Catings Envirnment Friendly, Fast Curing, Add Mildew Preventive, Suitable fr Smarter Meter. Has a 60 Shre A hardness.

Viscsity cps Recmmend Using Type Recmmend Curing Cnditin Acrylic 120 Spray, Dip, Brush 6min@25 UV-Acrylate 150 Spray, Brush 800mJ/cm 2 FS3000 Alchl Type Silicnes, RTV Silicne 2,000

52 Prduct Intrductin Prduct Descriptin Type EA6103 EA6106 Catings Envirnment Friendly, Fast Curing, Add Mildew Preventive, Suitable fr Smarter Meter. Has a 60 Shre A hardness. EA6106 is a dual UV-misture cure material. The initial cure is made with UV light and a secndary misture cure ver time. Viscsity cps Recmmend Using Type Recmmend Curing Cnditin Acrylic 120 Spray, Dip, Brush 6min@25 UV-Acrylate 150 Spray, Brush 800mJ/cm 2 FS3000 Alchl Type Silicnes, RTV Silicne 2,000 Spray, Dip, Brush 10min@25 FH1280AB FH1280 A/B is a tw-cmpnent epxy with high prtectin perfrmance Urethane 300 Spray, Dip, Brush 2 t 3 hurs at 80C Flurescent Indicatr, Easy t Use. Envirnment Friendly, Free Frm Benzene Slvent. TONSAN ADHESIVE, INC. tgether. we create

53 Frequent Prblems Frequent Prblems N-wetting Bubble Pinhle High welding spt withut cating Orange Peel Crack Capillarity Delaminatin TONSAN ADHESIVE, INC. tgether. we create

54 THANK YOU Greg Caswell Matt Perry (ffice) (cell) (cell) Zha Ralph Velazquez Virginia Manr Rd Ste 290, Beltsville MD

Nanocoatings: The Solution to All of Our Environmental Protection Problems?

Nanocoatings: The Solution to All of Our Environmental Protection Problems? Nancatings: The Slutin t All f Our Envirnmental Prtectin Prblems? 2015 NREL Phtvltaic Mdule Reliability Wrkshp February 25, 2015 Presented by Greg Caswell DfR Slutins 2004-2007 2010 Intrductin Applying