Kòm konpayi asirans lan nan eleman divès kalite ak mwaye a nan transmisyon siyal sikwi, Pkb te vin pati ki pi enpòtan ak kle nan pwodwi enfòmasyon elektwonik, bon jan kalite li yo ak nivo fyab detèmine bon jan kalite a ak fyab nan ekipman an antye. Sepandan, akòz pri ak rezon teknik, gen yon anpil nan pwoblèm echèk nan pwodiksyon PCB ak aplikasyon.

Pou sa a kalite pwoblèm echèk, nou bezwen sèvi ak kèk souvan itilize teknik analiz echèk asire bon jan kalite a ak nivo fyab nan PCB nan fabrikasyon. Papye sa a rezime dis teknik analiz echèk pou referans.

Mekanis ak analiz kòz echèk PCB

1. Yon enspeksyon vizyèl

Enspeksyon aparans se vizyèlman enspekte oswa itilize kèk enstriman senp, tankou mikwoskòp stereoskopik, mikwoskòp metalografik oswa menm loup, pou tcheke aparans PCB epi jwenn pati echwe yo ak prèv fizik ki enpòtan yo. Fonksyon prensipal la se lokalize echèk la ak preliminèman jije mòd nan echèk nan PCB. Aparans enspeksyon sitou tcheke polisyon PCB, korozyon, ki kote eksplozyon tablo, fil kous ak regilarite nan echèk, si li se pakèt oswa endividyèl, si li toujou konsantre nan yon zòn sèten, elatriye. In addition, the failure of many PCBS was discovered after the assembly of PCBA. Whether the failure was caused by the influence of the assembly process and materials used in the process also requires careful examination of the characteristics of the failure area.

2. X-ray fluoroskopi

Pou kèk pati ki pa ka enspekte pa aparans la, osi byen ke andedan PCB la nan twou ak lòt domaj entèn, nou dwe itilize sistèm radyoskopi radyografi pou tcheke. X-ray sistèm fluoroskopi se itilize nan epesè diferan materyèl oswa diferan dansite materyèl nan X-ray igroskopisite oswa transmissions nan prensip diferan nan D ‘. Teknoloji sa a se plis itilize yo tcheke ki kote domaj nan jwenti soude PCBA, nan domaj twou ak domaj nan aparèy BGA oswa CSP ak anbalaj dansite segondè. At present, the resolution of industrial X-ray fluoroscopy equipment can reach less than one micron, and is changing from two dimensional to three dimensional imaging equipment. There are even five dimensional (5D) equipment used for packaging inspection, but this 5D X-ray fluoroscopy system is very expensive, and rarely has practical application in the industry.

3. Seksyon analiz

Analiz tranch se pwosesis pou jwenn estrikti PCB seksyon kwa nan echantiyonaj, Mozayik, tranch, polisaj, korozyon, obsèvasyon ak yon seri de metòd ak etap. Abondan enfòmasyon sou mikrostruktur nan PCB (nan twou, kouch, elatriye) ka jwenn nan analiz tranch, ki bay yon bon baz pou pwochen amelyorasyon nan bon jan kalite. However, this method is destructive, once the slice is carried out, the sample will inevitably be destroyed; An menm tan an, metòd la nan kondisyon echantiyon yo wo, tan preparasyon echantiyon se tou long, bezwen an pou pèsonèl ki resevwa fòmasyon teknik yo fini. For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. Fè optik mikwoskòp acoustik

At present, c-mode ultrasonic scanning acoustic microscope is mainly used for electronic packaging or assembly analysis. It makes use of the amplitude, phase and polarity changes generated by the reflection of high-frequency ultrasound on the discontinuous interface of materials to image, and its scanning mode is to scan the information in the X-Y plane along the Z-axis. Therefore, scanning acoustic microscopy can be used to detect various defects, including cracks, delamination, inclusions, and voids, in components, materials, and PCB and PCBA. Internal defects of solder joints can also be directly detected if the frequency width of scanning acoustics is sufficient. Of a typical scanning acoustic image in color red alert said defects exist, because a large amount of plastic packaging components used in SMT process, by a lead into the process of lead-free technology, a large number of moisture reflow sensitive problem, namely the moisture absorption of powder coating devices will be at a higher temperature reflow lead-free process occurs within or substrate layer cracking phenomenon, Under the high temperature of lead-free process, common PCB will often burst board phenomenon. Nan pwen sa a, optik mikwoskòp la acoustic montre avantaj espesyal li yo nan deteksyon nondestructive nan milti-kouch PCB dansite. The general obvious bursting plate can be detected by visual inspection.

5. Analiz mikwo enfrawouj

Mikwo analiz enfrawouj se spèktroskopi enfrawouj konbine avèk metòd analiz mikwoskòp, li itilize diferan materyèl (sitou matyè òganik) sou prensip absòpsyon spectre enfrawouj la, analize konpozisyon konpoze materyèl yo, makonnen ak mikwoskòp la ka fè limyè vizib ak limyè enfrawouj. ak chemen limyè a, osi lontan ke anba jaden vizyèl la, ka gade pou analiz tras polyan òganik. Nan absans yon mikwoskòp, spèktroskopi enfrawouj ka anjeneral analize sèlman echantiyon gwo. In many cases, trace pollution in electronic process can lead to poor weldability of PCB pad or lead pin. It can be imagined that it is difficult to solve the process problem without the matching infrared spectrum of microscope. The main use of microscopic infrared analysis is to analyze the organic pollutants on the welding surface or solder spot surface, and analyze the causes of corrosion or poor solderability.

6. Analiz mikwoskopi analiz elektwonik

Scanning microscope elektwonik (SEM) se youn nan pi itil gwo-echèl elektwonik sistèm D ‘mikwoskopik pou analiz echèk. Prensip k ap travay li se fòme yon gwo bout bwa elèktron ak dyamèt dè dizèn a dè milye de angstrom (A) pa konsantre gwo bout bwa a elèktron emèt nan katod la akselere pa anod la. Anba aksyon defleksyon bobin optik la, Gwo bout bwa elèktron eskane sifas echantiyon an pwen pa pwen nan yon sèten tan ak espas espas. Gwo bout bwa elèktron enèji ki bonbade sifas echantiyon an epi jenere yon varyete enfòmasyon, ki ka kolekte epi anplifye pou jwenn divès grafik korespondan sou ekran ekspozisyon an. The excited secondary electrons are generated within the range of 5 ~ 10nm on the surface of the sample. Therefore, the secondary electrons can better reflect the surface topography of the sample, so they are most commonly used for morphology observation. Elektwon backscattered elektwon yo pwodwi nan a ranje 100 ~ 1000nm sou sifas echantiyon an, epi yo emèt karakteristik diferan ak diferans lan nan nimewo atomik nan sibstans la. Se poutèt sa, imaj elektwon backscattered la gen karakteristik morfolojik ak kapasite diskriminasyon nimewo atomik, ak Se poutèt sa, imaj elektwon backscattered la ka reflete distribisyon eleman chimik yo. Mikwoskòp elektwonik prezan an te trè pwisan, nenpòt estrikti amann oswa karakteristik sifas yo ka agrandi a dè santèn de milye de fwa pou obsèvasyon ak analiz.

In PCB or solder joint failure analysis, SEM is mainly used for failure mechanism analysis, specifically, is used to observe the surface morphology structure of the pad, solder joint metallographic structure, measurement of intermetallic compounds, solderable coating analysis and tin must be analyzed and measured. Different from the optical microscope, the scanning electron microscope produces electronic images, so it has only black and white colors. Moreover, the sample of the scanning electron microscope is required to conduct electricity, and the non-conductor and part of the semiconductor need to be sprayed with gold or carbon, otherwise the charge will gather on the surface of the sample and affect the sample observation. Anplis de sa, pwofondè nan jaden nan imaj la mikwoskòp elektwonik optik se pi gwo pase sa yo ki an mikwoskòp optik la, ki se yon metòd enpòtan pou analiz la nan estrikti a metallografik, ka zo kase mikwoskopik ak moustach fèblan.

7. X-ray energy spectrum analysis

Pi wo a mansyone mikwoskopi elektwonik anjeneral ekipe ak yon espektwomèt enèji X-ray. When the high-energy electron beam hit the surface, the surface material of the inner electrons in the atoms are bombarded escape, outer electrons to low energy level transition will inspire characteristic X ray, atomic energy level difference of different elements from different characteristic X ray is different, therefore, can send sample of the characteristics of X-ray as chemical composition analysis. An menm tan an, enstriman mizik ki koresponn yo respektivman rele espèktromètr dispèsyon (WDS pou kout) ak spèktromètr dispersyon enèji (EDS pou kout) selon longèdonn karakteristik oswa enèji karakteristik deteksyon siyal X-ray la. Rezolisyon spèktromèt la pi wo pase sa spèktromètr enèji a, ak vitès analiz spèktromètr enèji a pi vit pase sa spèktromètr enèji a. Paske nan gwo vitès ak pri ki ba nan spèktromètr enèji, jeneral mikwoskopi elektwonik SCANNING ekipe ak spèktromètr enèji.

Avèk mòd nan optik diferan nan gwo bout bwa elèktron, spèktromètr nan enèji ka analize pwen, liy lan ak avyon nan sifas la, epi jwenn enfòmasyon nan distribisyon diferan nan eleman yo.Point analysis yields all elements of a point; Analiz liy Yon analiz eleman fèt sou yon liy espesifye chak fwa, epi distribisyon liy tout eleman yo jwenn nan optik miltip. Analiz andigman Analiz tout eleman nan yon sifas yo bay. Kontni eleman ki mezire a se mwayèn ranje mezi sifas yo.

In the analysis of PCB, energy dispersive spectrometer is mainly used for the composition analysis of pad surface, and the elemental analysis of contaminants on the surface of pad and lead pin with poor solderability. Presizyon analiz quantitative nan spèktromètr enèji limite, epi kontni an mwens pase 0.1% jeneralman pa fasil pou detekte. Konbinezon an nan spectre enèji ak SEM ka jwenn enfòmasyon nan mòfoloji sifas ak konpozisyon ansanm, ki se rezon an pou kisa yo lajman itilize.

8. Photoelectron spèktroskopi (XPS) analiz

Echantiyon pa iradyasyon X ray, sifas la nan elektwon yo koki enteryè nan atòm a pral chape soti nan esklavaj la nan nwayo a ak solid sifas fòme, mezire enèji sinetik li yo Ex la, ka elektwon yo enteryè koki nan atòm a ka jwenn enèji a obligatwa nan Eb, Eb varye de eleman diferan ak koki elèktron diferan, li se “anprent dwèt” nan paramèt idantifikasyon atòm yo, fòmasyon nan liy espèk se spèktroskopi fotoelektron (XPS). XPS ka itilize pou analiz kalitatif ak quantitative nan eleman sou sifas fon (plizyè nanomèt) nan sifas echantiyon. Anplis de sa, enfòmasyon sou eta valans chimik nan eleman ka jwenn nan orè chimik nan enèji obligatwa. Li ka bay enfòmasyon kosyon ant eta valans kouch sifas la ak eleman ki antoure yo. The incident beam is X-ray photon beam, so insulation sample analysis can be carried out, without damaging the analyzed sample rapid multi-element analysis; Multikouch kapab tou analize longitudinalman pa agon ion nidite (gade ka ki anba a) ak sansiblite byen lwen pi gran pase spectre enèji (EDS). XPS se sitou itilize nan analiz pkb analiz bon jan kalite kouch, analiz polisyon ak analiz degre oksidasyon, yo nan lòd yo detèmine rezon ki fè yo gwo twou san fon nan soudabilite pòv yo.

9. Differential Scanning Calorim-etry

Yon metòd pou mezire diferans lan nan opinyon pouvwa ant yon sibstans ak yon sibstans referans kòm yon fonksyon nan tanperati (oswa tan) anba kontwòl tanperati pwograme. DSC is equipped with two groups of compensation heating wire under the sample and reference container, when the sample in the heating process due to the thermal effect and reference temperature difference δ T, through the differential heat amplifier circuit and differential heat compensation amplifier, so that the current flowing into the compensation heating wire changes.

The temperature difference δ T disappears, and the relationship between the difference of the thermal power of the two electrically compensated samples and the reference material with temperature (or time) is recorded. According to this relationship, the physicochemical and thermodynamic properties of the material can be studied and analyzed. DSC is widely used in PCB analysis, but is mainly used to measure the curing degree of various polymer materials used in PCB and glass state transformation temperature, these two parameters determine the reliability of PCB in the subsequent process.

10. Thermomechanical analyzer (TMA)

Tèmik analiz mekanik yo itilize pou mezire pwopriyete deformation solid, likid ak jèl anba fòs tèmik oswa mekanik anba kontwòl tanperati pwograme yo. Souvan itilize metòd chaj gen ladan konpresyon, ensèsyon PIN, etann, koube, elatriye. Sonde tès konsiste de fiks sou gwo bout bwa a cantilever ak sipò sezon prentan, atravè motè a nan chaj la aplike, lè deformation nan echantiyon rive, transfòmatè diferans yo detekte chanjman an, ak ansanm ak pwosesis la done, tankou tanperati, estrès ak souch apre ka materyèl la jwenn anba relasyon yo deformation chaj neglijab ak tanperati (oswa tan). Dapre relasyon ki genyen ant deformation ak tanperati (oswa tan), pwopriyete fizikochimik ak tèrmodinamik nan materyèl yo ka etidye ak analize. TMA se lajman ki itilize nan analiz PCB epi li se sitou itilize nan mezire de paramèt ki pi kritik nan PCB: koyefisyan ekspansyon lineyè ak tanperati tranzisyon vè. PCB ak koyefisyan ekspansyon twò gwo ap souvan mennen nan echèk ka zo kase nan twou metalize apre soude ak asanble.