Njengesithwali sezinto ezahlukahlukene kanye nehabhu lokudluliswa kwesiginali yesifunda, PCB isibe yingxenye ebaluleke kakhulu futhi esemqoka yemikhiqizo yolwazi ye-elekthronikhi, izinga layo kanye nokuthembeka kwayo kunquma ikhwalithi nokuthembeka kwayo yonke imishini. Kodwa-ke, ngenxa yezindleko nezizathu zobuchwepheshe, kunezinkinga eziningi zokwehluleka ekukhiqizeni kwe-PCB nasekusebenziseni.

Kulolu hlobo lwenkinga yokwehluleka, sidinga ukusebenzisa amasu wokuhlaziya ukuhluleka asetshenziswa kakhulu ukuqinisekisa ukuthi izinga lekhwalithi nokwethembeka kwe-PCB ekukhiqizeni. Leli phepha lifingqa izindlela eziyishumi zokuhlaziya ukwehluleka ukuthola inkomba.

Umshini nokubangela ukuhlaziywa kwe-PCB

1. Ukuhlola okubukwayo

Ukubukeka kokuhlola ukubheka ukuhlola noma ukusebenzisa ezinye izinto ezilula, njenge-microscope ye-stereoscopic, i-metallographic microscope noma ingilazi yokukhulisa, ukuhlola ukubukeka kwe-PCB bese uthola izingxenye ezihlulekile nobufakazi obufanele bomzimba. Umsebenzi oyinhloko ukuthola ukwehluleka futhi kuqala ukwahlulela imodi ukwehluleka PCB. Ukuhlola ukubukeka ikakhulu kuhlola ukungcoliswa kwe-PCB, ukugqwala, indawo okuqhuma kuyo ibhodi, i-wiring yesifunda kanye nokuhlala kwenzeka ukwehluleka, uma kuyi-batch noma kumuntu ngamunye, noma ngabe kugxilwe njalo endaweni ethile, njll. 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. I-X-ray fluoroscopy

Kwezinye izingxenye ezingenakuhlolwa ngokubukeka, nangaphakathi kwe-PCB ngembobo nokunye ukukhubazeka kwangaphakathi, kufanele sisebenzise uhlelo lwe-X-ray fluoroscopy ukuhlola. Uhlelo lwe-X-ray fluoroscopy ukusetshenziswa kobukhulu obuhlukile bezinto ezibonakalayo noma ukuminyana kwempahla ehlukile ye-X-ray hygroscopicity noma ukuhanjiswa kwemigomo ehlukile ekuthwebuleni izithombe. Lobu buchwepheshe busetshenziswa kakhulu ukubheka ukutholakala kwamaphutha kumajoyini we-PCBA solder, ngokusebenzisa amaphutha emigodi namaphutha kumadivayisi we-BGA noma we-CSP anokufakwa okuphezulu kwabantu. 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. Ukuhlaziywa kwesigaba

Ukuhlaziywa kwesilayidi kuyinqubo yokuthola isakhiwo sesigaba se-PCB ngokusebenzisa izibonelo zalokho, uMosisi, ucezu, ukupholisha, ukugqwala, ukubuka kanye nochungechunge lwezindlela nezinyathelo. Ulwazi oluningi mayelana nokwakheka kwe-PCB (ngembobo, ukumbozwa, njll.) Kungatholakala ngokuhlaziywa kocezu, okunikeza isisekelo esihle sokwenza ngcono ikhwalithi elandelayo. However, this method is destructive, once the slice is carried out, the sample will inevitably be destroyed; Ngasikhathi sinye, indlela yezidingo zesampula iphezulu, isikhathi sokulungiselela isampula naso side, isidingo sabasebenzi abaqeqeshiwe bokuqedela. For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. Iskena imicroscope ye-acoustic

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. Kuleli qophelo, ukuskena imicroscope ye-acoustic kukhombisa inzuzo yayo ekhethekile ekutholeni okungenabungozi kwe-PCB esezingeni eliphakeme kakhulu. The general obvious bursting plate can be detected by visual inspection.

5. Ukuhlaziywa kweMicroinfrared

Ukuhlaziywa kwe-infrared infrared ukwenza i-infrared spectroscopy kuhlanganiswe nendlela yokuhlaziya yesibonakhulu, isebenzisa izinto ezahlukahlukene (ikakhulukazi izinto eziphilayo) kumthetho wokumunwa kwe-infrared spectrum, ukuhlaziya ukwakheka kwezinto, kanye nesibonakhulu kungenza ukukhanya okubonakalayo nokukhanya kwe-infrared ngomzila okhanyayo, inqobo nje uma ungaphansi kwenkambu ebonakalayo, ungabheka ukuhlaziywa kokulandelwa kokungcolisa okuphilayo. Uma ingekho i-microscope, i-infrared spectroscopy ingahlaziya kuphela amasampula amakhulu kuphela. 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. Iskena ukuhlaziywa kwe-electron microscopy

Ukuskena imicroscope ye-electron (SEM) kungenye yezinhlelo ezisetshenziswayo ezisebenzisa kakhulu ukucwaninga kokuhluleka. Umgomo wayo osebenzayo ukwakha ugongolo lwe-electron ngobubanzi bamashumi kuya ezinkulungwaneni zama-angstroms (A) ngokugxila kugongolo lwe-electron olukhishwe ku-cathode esheshiswe yi-anode. Ngaphansi kwesenzo sokuphambuka kwekhoyili yokuskena, Ugongolo lwama-electron luhlola indawo yephuzu lesampula ngephuzu ngesikhathi esithile nokuhleleka kwesikhala. Igongolo le-elektroni elinamandla amakhulu liqhuma ebusweni besampula futhi likhiqiza imininingwane ehlukahlukene, engaqoqwa futhi ikhuliswe ukuthola imidwebo ehambisanayo ehlukahlukene esikrinini sokubonisa. 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. Ama-elektroni ajabule abuyiselwe emuva akhiqizwa ebangeni le-100 ~ 1000nm ebusweni besampula, futhi akhipha izici ezahlukile ngomehluko wenombolo ye-athomu yento. Ngakho-ke, isithombe se-elektroni esilahliwe sinezici ze-morphologic kanye nekhono lokubandlululwa kwenombolo ye-athomu, ngakho-ke, isithombe se-electron esilahlekile singabonisa ukusatshalaliswa kwezakhi zamakhemikhali. Isibonakhulu samanje se-electron microscope besinamandla amakhulu, noma isiphi isakhiwo esihle noma izici ezingaphezulu zingakhuliswa zibe ngamakhulu ezinkulungwane zezikhathi zokubukwa nokuhlaziywa.

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. Ngaphezu kwalokho, ukujula kwensimu yesithombe sokuskena se-electron microscope kukhulu kakhulu kunokwesibonakhulu se-optical, okuyindlela ebalulekile yokuhlaziywa kwesakhiwo se-metallographic, i-microscopic fracture kanye nentshebe yethini.

7. X-ray energy spectrum analysis

I-microscopy yokuskena eshiwo ngenhla ivame ukufakwa i-X-ray energy spectrometer. 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. Ngasikhathi sinye, izinsimbi ezihambisanayo zibizwa ngokulandelana zibizwa ngokuthi yi-spectrum dispersion spectrometer (i-WDS ngamafuphi) ne-energy dispersion spectrometer (i-EDS ngamafuphi) ngokuya ngobude besici noma amandla esici sokutholwa kwesiginali ye-X-ray. Ukuxazululwa kwe-spectrometer kuphakeme kune-spectrometer yamandla, futhi isivinini sokuhlaziya se-spectrometer yamandla sishesha kakhulu kunaleso se-spectrometer yamandla. Ngenxa yejubane eliphakeme nezindleko eziphansi zamasethrometri wamandla, i-SCANNING electron microscopy ejwayelekile ifakwe ama-spectrometer wamandla.

Ngemodi ehlukile yokuskena ka-beam ye-electron, i-spectrometer yamandla ingahlaziya iphuzu, ulayini nendiza ebusweni, futhi ithole imininingwane yokusatshalaliswa okuhlukile kwezinto.Point analysis yields all elements of a point; Ukuhlaziywa komugqa Ukuhlaziywa kwento eyodwa kwenziwa kulayini ocacisiwe isikhathi ngasinye, futhi ukusatshalaliswa komugqa kwazo zonke izinto kutholakala ngokuskena okuningi. Ukuhlaziywa kwendawo Ukuhlaziywa kwazo zonke izinto endaweni enikeziwe. Okuqukethwe kwento elinganisiwe isilinganiso sobubanzi bezilinganiso zomhlaba.

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. Ukunemba kokuhlaziywa kwamanani we-spectrometer yamandla kunqunyelwe, futhi okuqukethwe okungaphansi kuka-0.1% ngokuvamile akulula ukukuthola. Inhlanganisela yamandla we-energy ne-SEM ingathola ulwazi lwe-surface morphology nokwakheka ngasikhathi sinye, okuyisizathu sokuthi kungani isetshenziswa kabanzi.

8. Ukuhlaziywa kwe-Photoelectron spectroscopy (XPS)

Amasampula nge-X ray irradiation, ubuso bamakhemikhali angaphakathi egobolondo e-athomu azophuma ebugqilini be-nucleus nobuso obuqinile bokwakha, kulinganisa amandla ayo we-kinetic i-Ex, amagobolondo angaphakathi egobolondo le-athomu angatholakala amandla okubopha I-Eb, i-Eb yahlukahluka ezintweni ezahlukahlukene negobolondo elehlukile le-elektroni, “yizimpawu zeminwe” zamapharamitha wokuhlonza ama-athomu, ukwakheka kolayini we-spectral yi-photoelectron spectroscopy (XPS). I-XPS ingasetshenziselwa ukuhlaziywa kwekhwalithi nobungako bezinto ezisendaweni engajulile (ama-nanometer amaningana) wesampula ebusweni. Ngaphezu kwalokho, imininingwane mayelana namakhemikhali e-valence ithi yezinto ingatholakala ekushintsheni kwamakhemikhali kwamandla okubopha. Inganikeza imininingwane yesibopho esiphakathi kwesimo se-valence sesendlalelo sezinto nezinto ezizungezile. 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; Ama-multilayers nawo angahlaziywa isikhathi eside ngokudonswa kwe-argon ion (bona icala elingezansi) ngokuzwela okukhulu kakhulu kune-energy spectrum (EDS). I-XPS isetshenziswa kakhulu ekuhlaziyweni kokuhlaziywa kwekhwalithi yokumboza kwe-PCB, ukuhlaziywa kokungcola kanye nokuhlaziywa kwezinga le-oxidation, ukuze kunqunywe isizathu esijulile sokungaxhumi kahle.

9. Differential Scanning Calorim-etry

Indlela yokulinganisa umehluko ekufakweni kwamandla phakathi kwento nento eyisithenjwa njengomsebenzi wethempelesha (noma isikhathi) ngaphansi kokulawulwa kokushisa okuhleliwe. 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)

I-Thermal Mechanical Analysis isetshenziselwa ukukala izakhiwo zokuguqulwa kwezinto eziqinile, uketshezi nama-gel ngaphansi kwamandla we-Thermal noma iMechanical ngaphansi kokulawulwa kokushisa okuhleliwe. Izindlela zokulayisha ezisetshenziswa ngokujwayelekile zifaka ukucindezelwa, ukufakwa kwephini, ukuzelula, ukugoba, njll. Uphenyo lokuhlola luqukethe okugxilwe kugongolo lwe-cantilever kanye nokusekelwa kwentwasahlobo kwe-helical, ngokusebenzisa imoto yomthwalo osetshenzisiwe, lapho kwenzeka ukusetshenzwa kwesibonelo, uguquko lwesibalo ukuthola ushintsho, futhi kanye nokucutshungulwa kwedatha, njengokushisa, ukucindezela kanye nobunzima ngemuva okokusebenza kungatholakala ngaphansi kobudlelwano bokushintshwa kwemithwalo obuncane bokushisa (noma isikhathi). Ngokuya ngobudlelwano obuphakathi kokushintshwa nokushisa (noma isikhathi), izakhiwo ze-physicochemical kanye ne-thermodynamic zezinto zingafundwa futhi zihlaziywe. I-TMA isetshenziswa kakhulu ekuhlaziyweni kwe-PCB futhi isetshenziswa kakhulu ekulinganiseni imingcele emibili ebaluleke kakhulu ye-PCB: ukushisa okulingana kokulingana kanye nokushisa kwengilazi kwenguquko. I-PCB ene-coefficient enkulu kakhulu yokunwebeka izovame ukuholela ekwehlulekeni ukwehluleka kwezimbobo zensimbi ngemuva kokushisela nokuhlangana.