As the carrier of various components and the hub of circuit signal transmission, PCB informazio elektronikoko produktuen atalik garrantzitsuena eta funtsezkoena bihurtu da. Kalitate eta fidagarritasun mailak ekipamendu osoaren kalitatea eta fidagarritasuna zehazten ditu. Hala ere, kostuak eta arrazoi teknikoak direla eta, PCBaren ekoizpenean eta aplikazioan arazo ugari daude.

Hutsegite arazo mota honetarako, normalean erabilitako akatsak aztertzeko teknika batzuk erabili behar ditugu fabrikazioan PCBaren kalitatea eta fidagarritasuna bermatzeko. Artikulu honek erreferentzia gisa hutsegiteak aztertzeko hamar teknika laburbiltzen ditu.

PCBaren hutsegitearen mekanismoa eta kausa aztertzea

1. Ikusizko ikuskapena

Appearance inspection is to visually inspect or use some simple instruments, such as stereoscopic microscope, metallographic microscope or even magnifying glass, to check the appearance of PCB and find the failed parts and relevant physical evidence. The main function is to locate the failure and preliminarily judge the failure mode of PCB. Itxuraren ikuskapenean, batez ere, PCBen kutsadura, korrosioa, taulako leherketaren kokapena, zirkuituaren kableatua eta hutsegitearen erregulartasuna egiaztatzen dira, bat-batekoa edo banakoa bada, beti eremu jakin batean kontzentratuta dagoen, etab. 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 izpien fluoroskopia

Itxurak ikuskatu ezin dituen zenbait ataletarako, baita PCBaren barrualdea zuloaren bidez eta beste barne akats batzuetarako ere, X izpien fluoroskopia sistema erabili behar dugu egiaztatzeko. X izpien fluoroskopia sistema materialaren lodiera desberdinak edo X izpien higroskopikotasunaren edo printzipio desberdinen transmisioaren irudiaren erabilerarako material desberdinak erabiltzea da. Teknologia hau gehiago erabiltzen da PCBA soldadura artikulazioetan akatsen kokapena egiaztatzeko, dentsitate handiko ontziak dituzten BGA edo CSP gailuetako zulo akatsen eta akatsen bidez. 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. Section analysis

Slice analysis is the process of obtaining PCB cross section structure through sampling, Mosaic, slice, polishing, corrosion, observation and a series of methods and steps. Abundant information about the microstructure of PCB (through hole, coating, etc.) can be obtained by slice analysis, which provides a good basis for the next quality improvement. However, this method is destructive, once the slice is carried out, the sample will inevitably be destroyed; Aldi berean, laginaren eskakizunen metodoa handia da, laginak prestatzeko denbora ere luzea da, eta prestatutako langile teknikoen beharra osatu behar da. For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. Eskaneatzeko mikroskopio akustikoa

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. Une honetan, eskaneatzeko mikroskopio akustikoak bere abantaila berezia erakusten du geruza anitzeko dentsitate handiko PCBaren detekzio ez suntsitzailean. The general obvious bursting plate can be detected by visual inspection.

5. Mikroinfragorrien analisia

Mikro infragorriaren analisia infragorrien espektroskopia mikroskopioaren analisirako metodoarekin konbinatuta dago, material desberdina erabiltzen du (batez ere materia organikoa) espektro infragorriaren xurgapenaren printzipioan, materialen konposizio konposatua aztertuz, mikroskopioarekin batera argi ikusgaia eta argi infragorria egin daitezke. argiaren bidearekin, betiere ikusizko eremuaren azpian, arrasto kutsatzaile organikoen analisia bila dezake. Mikroskopiorik ezean, infragorrien espektroskopiak lagin handiak soilik azter ditzake normalean. 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. Mikroskopia elektronikoaren eskaneatze analisia

Eskaneatze mikroskopio elektronikoa (SEM) eskala handiko irudi elektronikoko mikroskopiako sistema erabilgarrienetako bat da porrotak aztertzeko. Bere funtzionamendu printzipioa hamarkadako milaka angstromo (A) diametroa duen elektroi izpi bat osatzea da, anodoak azeleratutako katodotik igorritako elektroi izpia fokatuz. Eskaneatze bobina desbideratzeko ekintzaren azpian, Elektroi izpiak laginaren azalera puntuz puntu eskaneatzen du denbora eta espazio ordena jakin batean. Energia handiko elektroi izpiak laginaren gainazala bonbardatzen du eta askotariko informazioa sortzen du, bistaratu eta anplifika daitekeena pantailan dagozkion hainbat grafiko lortzeko. 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. Atzera barreiatutako elektroi kitzikatuak 100 ~ 1000 nm bitarteko tartean sortzen dira laginaren gainazalean, eta substantziaren zenbaki atomikoaren aldearekin ezaugarri desberdinak igortzen dituzte. Hori dela eta, atzera barreiatutako elektroien irudiak ezaugarri morfologikoak eta zenbaki atomikoak bereizteko gaitasuna ditu eta, beraz, atzera barreiatutako elektroi irudiak elementu kimikoen banaketa islatu dezake. Gaur egungo eskaneatze-mikroskopio elektronikoa oso indartsua izan da, edozein egitura edo azaleko ezaugarri fin ehunka milaka aldiz handitu daitezke behatzeko eta aztertzeko.

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. Gainera, eskaneatutako mikroskopio elektronikoko irudiaren eremuaren sakonera mikroskopio optikoa baino askoz ere handiagoa da, hau da, egitura metalografikoa, haustura mikroskopikoa eta eztainu bigoteak aztertzeko metodo garrantzitsua.

7. X-ray energy spectrum analysis

Aipatutako eskaneatze-mikroskopia elektronikoa normalean X izpien energia espektrometro batez hornituta dago. 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. Aldi berean, dagozkien tresnei hurrenez hurren espektroaren barreiatze espektrometroa (laburra WDS) eta energia barreiatzeko espektrometroa (EDS laburra) deitzen zaie X izpien seinalea hautemateko uhin luzera edo energia bereizgarriaren arabera. Espektrometroaren bereizmena energia espektrometroarena baino handiagoa da, eta energia espektrometroaren analisiaren abiadura energia espektrometroarena baino azkarragoa da. Energiaren espektrometroen abiadura handia eta kostu txikia dela eta, SCANNING mikroskopia elektroniko orokorra energia espektrometroekin hornituta dago.

With the different scanning mode of electron beam, the energy spectrometer can analyze the point, line and plane of the surface, and obtain the information of different distribution of elements.Point analysis yields all elements of a point; Line analysis One element analysis is performed on a specified line each time, and the line distribution of all elements is obtained by multiple scanning. Azaleraren analisia Azalera jakin bateko elementu guztien analisia. Neurtutako elementuen edukia gainazaleko neurketen barrutiaren batez bestekoa da.

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. Energiaren espektrometroaren analisi kuantitatiboaren zehaztasuna mugatua da, eta% 0.1etik beherako edukia ez da orokorrean erraz antzematen. Energia espektroaren eta SEMaren konbinazioak gainazaleko morfologiaren eta konposizioaren informazioa aldi berean lor dezake, horregatik oso erabiliak diren arrazoia da.

8. Fotoelektroi espektroskopia (XPS) azterketa

X izpien erradiazioaren bidezko laginak, atomoaren barruko oskolaren elektroien gainazala nukleoaren loturatik ihes egingo da eta solidoa osatuz, bere energia zinetikoa Ex neurtuz, atomoaren barne oskolaren elektroiek lotura-energia lor dezakete. Eb, Eb elementu desberdinen eta elektroi-oskol desberdinen artean aldatzen da, atomoak identifikatzeko parametroen “hatz-markak” dira, lerro espektralaren eraketa fotoelektroi espektroskopia da (XPS). XPS laginaren gainazaleko gainazaleko gainazaleko (hainbat nanometro) elementuen analisi kualitatibo eta kuantitatiboa egiteko erabil daiteke. Gainera, elementuen baliozko egoera kimikoei buruzko informazioa lotura-energiaren desplazamendu kimikoetatik lor daiteke. Gainazal geruzaren balentzia egoeraren eta inguruko elementuen arteko loturaren informazioa eman dezake. 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; Multilayers can also be analyzed longitudinally by argon ion stripping (see the case below) with far greater sensitivity than energy spectrum (EDS). XPS batez ere PCB estalduraren kalitatearen analisian, kutsaduraren analisian eta oxidazio graduen analisian erabiltzen da, soldadura txarraren arrazoi sakona zehazteko.

9. Differential Scanning Calorim-etry

Substantzia baten eta erreferentziazko substantzia baten arteko potentziaren sarrera aldea neurtzeko metodoa tenperatura programatuaren kontrolean (edo denboraren) arabera. 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)

Thermal Mechanical Analysis is used to measure the deformation properties of solids, liquids and gels under Thermal or Mechanical forces under programmed temperature control. Commonly used load methods include compression, pin insertion, stretching, bending, etc. Test probe consists of fixed on the cantilever beam and helical spring support, through the motor of the applied load, when the specimen deformation occurs, differential transformer to detect the change, and together with the data processing, such as temperature, stress and strain after the material can be obtained under the negligible load deformation relations with temperature (or time). According to the relationship between deformation and temperature (or time), the physicochemical and thermodynamic properties of materials can be studied and analyzed. TMA is widely used in PCB analysis and is mainly used in measuring the two most critical parameters of PCB: linear expansion coefficient and glass transition temperature. PCB with too large expansion coefficient will often lead to fracture failure of metallized holes after welding and assembly.