As we all know, the continuous progress of electronic equipment and circuit technology, the peak of engineering art in the design, development and manufacture of ibhodi yesekethe eprintiweyo (I-PCB) kungqinwe ngabantu kwihlabathi liphela. Our planet is full of highly intelligent machines, automated robots and scientific marvels, and of course, there are plenty of PCBS in every corner of the planet, no matter what country or city it is. Nangona kunjalo, ezi PCBS zahlukile ekusebenzeni, ubunzima, iindleko zokwenziwa, umgangatho kunye nokuthembeka. This article focuses on the last two points, the quality and reliability of PCBS.

Ewe, abathengi abanokubakho bahlala befuna i-elektroniki ekumgangatho ophezulu, kodwa oku kuyabiza kakhulu kwaye kunokubandakanya iinkqubo zokwenza izinto ezintsonkothileyo. Kwinkqubo entsonkothileyo yokuvelisa i-PCB, ukuhlangana kunye nokuvavanywa, kukho inkqubo ebaluleke kakhulu ebizwa ngokuba yi “conformal coating” yePCB. This conformal coating is very important in PCBS in terms of quality and reliability.

What is conformal coating and its importance:

Conforming coating, an ultra-thin protective coating of polymer film, can be used in conjunction with assemblies mounted on assembly surfaces to protect assembly leads, solder joints, exposed wiring, and other metal points on the PCB surface from corrosion, dust, or chemicals due to various operating or environmental conditions.

Ingubo ehambelanayo ingaba yincinci njenge-25 microns kwaye “ihambelana” kubume kunye nobume bebhodi yesekethe. Njengoko kukhankanyiwe ngasentla, isizathu sokusebenzisa ukutyabeka okungqinelanayo kumphezulu (phezulu nasezantsi) sePCB kukukhusela i-PCB kwiimeko ezimbi zangaphandle zokusingqongileyo, ngokwandisa ubomi benkonzo yePCB kunye nezixhobo zombane ezinxulumene noko.

Njengamaqondo obushushu aphezulu afunyenwe kwimizi-mveliso, kumzi-mveliso, nakwizinto zombane ezinamandla aphezulu, ezi PCBS zineengubo ezimiselweyo zinokumelana nobushushu obugqithisileyo. Kwangokunjalo, izixhobo ze-elektroniki ezifakwe kwiindawo / kwiindawo ezikufutshane nolwandle okanye ulwandle zinokuchaphazeleka kukufuma okuphezulu, njengokuhamba ngenqanawa izixhobo zombane ezinokubakho kumhlwa / ukhukuliseko olunokubangela i-oxidation yesinyithi. Similarly, in microbiology laboratories and the medical industry, sensitive electronic equipment can be exposed to toxic chemicals, acidic and alkaline solvents that can accidentally spill onto a PCB, but the PCB’s “conformation coating” will protect the PCB and components from fatal injury.

Ungasifaka kanjani isicelo sokudibanisa ngokufanayo?

In fact, the method of applying “conformal paint” in the right way is so important that careful consideration must be given to how conformal paint is applied. It is as important to choose suitable conformal coating materials.

Ezona zinto ziphambili zichonga ukusetyenziswa ngokufanelekileyo kwento yokuhombisa:

1- Ukutyeba kwepeyinti

2- The level of coverage achieved

3- The degree of adhesion of paint to wood panels and their components.

There are five methods for applying conformal coatings:

1- Paint by hand with a brush

Ukubhabha kwe-2- Aerosol

3- Atomizing spray gun coating

4- Automatic dip coating

5- Automatic selection of coating

Inkqubo yokuphilisa yokutyibilika / yokomisa:

Conformal coatings themselves can be classified according to the drying and curing methods used after conformal coatings are completed. Ezi ndlela zezi:

1- Heat/heat curing: Conformal coating is dried at high temperature. Drying rate is much faster than normal room temperature drying/curing.

2- Ukunyanga ukupholisa: Ukutyabeka okungahambelaniyo kwePCB kuyomiswa kubushushu obujikelezileyo, ukufuma emoyeni kuyayinciphisa inkqubo yokunyanga okanye yokumisa.

3- ULTRAVIOLET (UV) curing: Here PCB with conformal coating is exposed to UV radiation. Amandla e-UV amisela isantya esinyangayo se-PCB efanayo

Ukunyanga i-4- iOxation

5- Catalytic curing: This is the process of curing conformal coating in which two materials are fused together, one of which is conformal coating. Xa ukutyabeka kudityaniswe nezinye izinto zokunxibelelanisa, inkqubo yokuphilisa ayinakumiswa ide igqitywe.

Classification of conformal coatings:

There are five main conformal coatings used: acrylic resin, epoxy resin, silicone, polyurethane (PU) and polyparaxylene coating.

L Acrylic intlaka (AAR):

Acrylics are ideal for (low-cost and high-volume) common electronics because AAR is inexpensive and can be easily applied to PCB surfaces by brush, dip, and manual or automatic spraying, reducing turnaround time and producing cost-effective products.

inzuzo:

1 – ixabiso eliphantsi

2- Easy for manual or automatic robot applications

3- Easy to rework

4- Excellent moisture protection

5- Good surface elasticity, can withstand static voltage discharge, and does not react with the atmosphere, therefore helps cure through solvent evaporation

Ilishwa:

1- Due to the use of atmospheric curing/drying methods for this material, proper ventilation systems need to be ensured

2- Ukugcinwa kwe-viscosity ephantsi

3- ukumelana nokunxiba okuphantsi kunye nokumelana neekhemikhali

L Epoxy conformal coating (ER) :

Conformal coatings based on epoxy resins can be completed by hand brush, spray or dip coating. Ukutshiza kuyacetyiswa kwimiqulu emikhulu nakwivolumu encinci okanye kumzekelo wePCBS.

inzuzo:

1- High moisture resistance and good dielectric resistance

2- Excellent chemical resistance, abrasion resistance, moisture resistance and high temperatures up to 150 O C

Ilishwa:

1-epoxy conformal paint is very hard and rigid and can damage PCB and its components if attempted peeling or removal. Susa isambatho ngokusebenzisa isinyibilikisi esiyingozi

2- Ukusebenza kakubi kobushushu obuphantsi

3- Ukuphilisa okuphezulu okuphunguliweyo

4- Kunzima ukwenza kwakhona

L abicah resin (OSR) ukutyabeka conformal:

The softest of the above two types of conformal coatings is silicone resin (OSR) conformal coatings. They are widely used in LED lamp PCBS without reducing light intensity or color change. Ideal for PCB installation at high humidity and exposure to air. Suitable for PCB with high operating temperature and high power

inzuzo:

1- Ukumelana kakuhle kweekhemikhali, ukuxhathisa ukufuma, ityuwa yokutshiza kunye namaqondo aphezulu ukuya kuthi ga kwi-200 OC

2- Good flexibility makes it resistant to vibration stress on PCB from external environment.

I-3- Ifanelekile izicelo zangaphandle ze-PCB ezinomswakama ophezulu

Okubi:

1- Musa ukunxiba ukumelana ngenxa yeempawu zerabha

2- Can be reworked, but not easily, requiring special solvents, long soaking times and stirring like a brush or ultrasonic bath

3- Low mechanical strength, weak adhesion to PCB substrate

L Polyurethane (DB) ukutyabeka okumiselweyo:

Ilungele ukusetyenziswa kwe-PCB kwizithuthi, kwimizi-mveliso, kwizixhobo kunye nakunxibelelwano ngomnxeba. Kwi-aerospace, ngakumbi, umphunga wamafutha uhlala ungqubana kunye nomzimba ophambili wezixhobo zombane kwaye ke ungene ngaphakathi kwaye uchaphazele ibhodi yePCB

inzuzo:

1- High resistance to moisture, chemicals (acid and alkali) and wear

Ilishwa:

1- Emva kwexesha elide lenkqubo yokunyanga egqibeleleyo, ihlala ijika ibe tyheli kumaqondo obushushu aphezulu ngenxa yomxholo wayo ophezulu we-VOC

2- Njenge-silicon, akukho lula ukuyisusa ngokupheleleyo

L polyparaxylene conformal coating:

This type of coating is suitable for avionics, microelectronics, sensors, high-frequency circuits, and densely populated PCB-based components. It is applied by means of vapor deposition.

inzuzo:

1- Excellent dielectric strength

2- High resistance to moisture, solvents, extreme temperatures and acid corrosion

3- Can be applied evenly with very thin paint.

Ilishwa:

1- Disassembly/rework is very difficult

2- High cost is the biggest drawback.