As the carrier of various components and the hub of circuit signal transmission, PCB ya zama mafi mahimmanci da mahimmin ɓangaren samfuran bayanan lantarki, ƙimar sa da amincin sa yana ƙaddara inganci da amincin duk kayan aikin. Koyaya, saboda farashi da dalilai na fasaha, akwai matsalolin gazawa da yawa a cikin samarwa da aikace -aikacen PCB.

Don irin wannan matsalar gazawar, muna buƙatar amfani da wasu dabarun nazarin gazawar da aka saba amfani dasu don tabbatar da ƙima da amincin matakin PCB a masana’antu. Wannan takarda ta taƙaita dabarun nazarin gazawa goma don tunani.

Mechanism da haifar da bincike na gazawar PCB

1. Binciken gani

Binciken bayyanar shine don dubawa ko amfani da wasu kayan aiki masu sauƙi, kamar microscope stereoscopic, microscope microscope ko ma gilashin ƙara girma, don duba bayyanar PCB kuma nemo ɓangarorin da suka gaza da shaidar zahiri da ta dace. Babban aikin shine gano gazawar kuma fara yanke hukunci akan yanayin gazawar PCB. Binciken bayyanar yafi bincika PCB gurɓataccen iska, lalata, wurin fashewar jirgi, wayoyin kewaya da kuma gazawar yau da kullun, idan ƙungiya ce ko mutum ɗaya, ko yana mai da hankali koyaushe a wani yanki, da dai sauransu. 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 fluoroscopy

Ga wasu ɓangarorin waɗanda bayyanar ba za a iya bincika su ba, har ma da cikin PCB ta cikin rami da sauran lahani na ciki, dole ne mu yi amfani da tsarin X-ray fluoroscopy don dubawa. Tsarin fluoroscopy na X-ray shine amfani da kauri daban-daban na kayan abu ko yawa daban-daban na hygroscopicity na X-ray ko watsa ƙa’idodi daban-daban zuwa hoto. An fi amfani da wannan fasaha don bincika wurin lahani a cikin gidajen haɗin PCBA, ta hanyar lahani da lahani a cikin na’urorin BGA ko CSP tare da fakitin yawa. 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. Binciken sashe

Binciken yanki shine tsarin samun tsarin sashin giciye na PCB ta hanyar samfuri, Mosaic, yanki, gogewa, lalata, kallo da jerin hanyoyin da matakai. 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; A lokaci guda, hanyar samfuran samfuran suna da yawa, lokacin shirya samfurin ma yana da tsawo, buƙatar ƙwararrun ƙwararrun ƙwararru don kammalawa. For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. Ana dubawa microscope

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. A wannan gaba, microscope na sikirin kayan adon yana nuna fa’idar sa ta musamman a cikin gano ɓarna na PCB mai ɗimbin yawa. The general obvious bursting plate can be detected by visual inspection.

5. Microinfrared bincike

Micro infrared analysis shine infrared spectroscopy haɗe tare da hanyar bincike na madubin microscope, yana amfani da abubuwa daban -daban (galibi kwayoyin halitta) akan ƙa’idar shaye -shaye na infrared, nazarin abun da ke cikin kayan, haɗe tare da madubin microscope na iya yin haske da haske infrared tare da hanyar haske, muddin a ƙarƙashin filin gani, na iya neman bincike na gano gurɓatattun ƙwayoyin cuta. Idan babu na’urar hangen nesa (microscope), ma’anar infrared spectroscopy na iya yin nazarin manyan samfura kawai. 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. Binciken microscopy na lantarki

Scanning electron microscope (SEM) yana ɗaya daga cikin mafi girman fa’idar tsarin ƙirar ƙirar ƙirar lantarki don nazarin gazawa. Ka’idar aikinsa ita ce ta samar da katako na lantarki tare da diamita goma zuwa dubun dubun angstroms (A) ta hanyar mai da hankali kan katakon wutar lantarki da ake fitarwa daga cathode wanda anode ya hanzarta. A ƙarƙashin aikin karkatar da murfin abin dubawa, Itacen lantarki yana bincika saman samfurin samfurin ta aya a cikin wani lokaci da tsarin sarari. Ƙarfin wutar lantarki mai ƙarfin kuzari yana tayar da saman samfurin kuma yana haifar da bayanai iri-iri, waɗanda za a iya tattarawa da haɓaka don samun zane-zane iri-iri masu dacewa akan allon nuni. 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. Ana samar da wutar lantarki mai jujjuyawar baya a cikin kewayon 100 ~ 1000nm a saman samfurin, kuma suna fitar da halaye daban -daban tare da bambancin lambar atomic na abu. Sabili da haka, hoton wutar lantarki na baya yana da sifofi na morphologic da ikon nuna bambancin lambar atomic, sabili da haka, hoton lantarki na baya zai iya nuna rabon abubuwan sunadarai. Madubin dubawar lantarki na yanzu yana da ƙarfi sosai, duk wani tsari mai kyau ko fasali na ƙasa ana iya ɗaukaka shi zuwa ɗaruruwan dubban lokuta don kallo da bincike.

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. Bugu da ƙari, zurfin filin hoton sikirin microscope na lantarki yana da girma fiye da na madubin dubawa, wanda shine muhimmin hanya don nazarin tsarin ƙirar ƙarfe, raunin microscopic da tabar wiwi.

7. X-ray energy spectrum analysis

Abubuwan da aka ambata a sama da aka ambata na lantarki microscopy galibi suna sanye da na’urar hangen nesa na 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. A lokaci guda, ana kiran kayan aikin daidai gwargwadon watsawar bakan (WDS a takaice) da ƙimar watsawar kuzari (EDS a takaice) gwargwadon maƙallan halayyar ko kuzari na gano siginar X-ray. Ƙudurin ma’aunin ma’aunin ya fi na ma’aunin kuzari, kuma saurin bincike na ma’aunin kuzari yana da sauri fiye da na kuzari. Saboda tsananin saurin gudu da ƙarancin farashin masu siyar da makamashi, babban SCANNING electron microscopy an sanye shi da ma’aunin makamashi.

Tare da yanayin sikelin daban -daban na katako na lantarki, spectrometer na makamashi na iya nazarin ma’ana, layi da jirgin saman farfajiya, da samun bayanan rarraba abubuwa daban -daban.Point analysis yields all elements of a point; Binciken layi Ana yin nazarin kashi ɗaya akan takamaiman layi kowane lokaci, kuma rarraba layin duk abubuwan ana samun su ta hanyar dubawa da yawa. Binciken saman Bincike na dukkan abubuwan da ke cikin farfajiyar da aka bayar. Abun da aka auna abun ciki shine matsakaicin ma’aunin ma’aunin farfajiya.

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. Daidaitaccen ƙididdigar ƙididdigar ma’aunin kuzari yana da iyaka, kuma abun da ke ƙasa da 0.1% gabaɗaya ba mai sauƙin ganewa bane. Haɗuwa da bakan makamashi da SEM na iya samun bayanan ilimin halittar ƙasa da abun da ke ciki lokaci guda, wanda shine dalilin da yasa ake yawan amfani da su.

8. Binciken Photoelectron spectroscopy (XPS)

Samfurori ta hanyar hasken ray ray, farfajiyar wutar lantarki na harsashi na atom zai tsere daga kangin tsakiya da tsayayyen farfajiya, auna ƙarfin kuzarinsa na Ex, za a iya samun wutar lantarki na ciki na atom. Eb, Eb sun bambanta daga abubuwa daban -daban da kuma harsashin lantarki daban -daban, shine “yatsan yatsa” na sigogin tantance atom, ƙirar layin baƙaƙe shine sikirin hoto (XPS). Ana iya amfani da XPS don ƙididdigar ƙima da ƙididdigar abubuwa akan farfajiya mara zurfi (nanometers da yawa) na samfurin samfurin. Bugu da kari, ana iya samun bayanai game da jihohin valence na sinadarai daga canjin sinadaran makamashin dauri. Yana iya ba da bayanin haɗin gwiwa tsakanin yanayin valence na saman farfajiya da abubuwan da ke kewaye. 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; Hakanan ana iya yin nazarin masu yawa da yawa ta hanyar tsage argon ion (duba shari’ar da ke ƙasa) tare da mafi girman hankali fiye da bakan makamashi (EDS). XPS galibi ana amfani da shi ne a cikin nazarin ingancin ingancin murfin PCB, nazarin gurɓataccen iska da nazarin digirin oxyidation, don tantance zurfin dalilin rashin walƙiya mara kyau.

9. Differential Scanning Calorim-etry

Hanya na auna bambanci a shigar da wuta tsakanin wani abu da wani abu mai nuni azaman aikin zafin jiki (ko lokaci) ƙarƙashin sarrafa zafin jiki. 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. Binciken gwajin ya ƙunshi tsayayye akan katakon cantilever da goyan bayan bazara na helical, ta hanyar injin da aka yi amfani da shi, lokacin da ƙirar samfurin ta faru, mai canzawa daban don gano canjin, kuma tare da sarrafa bayanai, kamar zazzabi, damuwa da damuwa bayan za a iya samun kayan a ƙarƙashin alaƙar ɓarna mai nauyi tare da zafin jiki (ko lokaci). Dangane da alaƙar da ke tsakanin ɓarna da zafin jiki (ko lokaci), ana iya yin nazarin da nazarin kimiyyar sinadarai da kayan ɗanyen ɗimbin kayan. Ana amfani da TMA sosai a cikin bincike na PCB kuma galibi ana amfani dashi don auna sigogi biyu mafi mahimmancin PCB: daidaiton faɗaɗa layin layi da zafin zafin canji na gilashi. PCB tare da babban maɗaukakiyar faɗaɗawa galibi zai haifar da raunin raunin ramukan ƙarfe bayan walda da taro.