As the carrier of various components and the hub of circuit signal transmission, PCB parantos janten bagian pangpentingna sareng konci produk inpormasi éléktronik, tingkat kualitas sareng reliabilitasna ngajantenkeun kualitas sareng reliabilitas sadaya alat. Nanging, kusabab biaya sareng alesan téknis, aya seueur masalah gagal dina produksi sareng aplikasi PCB.

Pikeun masalah gagal sapertos ieu, urang kedah nganggo sababaraha téhnik analisis kagagalan anu biasa dianggo pikeun mastikeun tingkat kualitas sareng reliabilitas PCB dina manufaktur. Tulisan ieu nyimpulkeun sapuluh téhnik analisis kagagalan pikeun rujukan.

Mékanisme sareng nyababkeun analisis kagagalan PCB

1. Pamariksaan visual

Pamariksaan penampilan nyaéta sacara visual mariksa atanapi nganggo sababaraha instrumen saderhana, sapertos mikroskop stereoskopik, mikroskop metallographic atanapi bahkan kaca pembesar, pikeun mariksa tampilan PCB sareng mendakan bagian-bagian anu gagal sareng buktina fisik anu aya hubunganana. Fungsi utami nyaéta milarian kagagalan sareng sateuacanna nangtoskeun modeu kagagalan PCB. Pamariksaan panampilan utamina cek polusi PCB, korosi, lokasi ledakan dewan, sambungan kabel sirkuit sareng rutinitas kagagalan, upami éta batch atanapi individu, naha éta salawasna dikonsentrasi dina daérah anu tangtu, jst. 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. Fluoroskopi sinar-X

Kanggo sababaraha bagian anu teu tiasa dipariksa ku penampilan, ogé bagian jero PCB ngalangkungan liang sareng cacat internal sanésna, urang kedah nganggo sistem fluoroskopi sinar-X pikeun mariksa. Sistem fluoroskopi sinar-X nyaéta panggunaan kandel bahan anu béda-béda atanapi kapadetan bahan anu béda-béda tina hibroskopisitas sinar-X atanapi transmisi prinsip anu béda-béda pikeun pencitraan. Téknologi ieu langkung seueur dianggo pikeun mariksa lokasi cacad dina sendi solder PCBA, ngalangkungan cacat liang sareng cacat dina alat BGA atanapi CSP kalayan bungkus kapadetan tinggi. 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. Analisis bagian

Analisis keureut mangrupikeun prosés kéngingkeun struktur penampang PCB ngalangkungan sampling, mosaik, keureutan, polesan, korosi, observasi sareng sababaraha cara sareng léngkah. 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; Dina waktos anu sasarengan, metode sarat sampel anu luhur, waktos persiapan sampel ogé panjang, kabutuhan tanaga téknis terlatih pikeun réngsé. For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. Nyeken mikroskop akustik

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. Dina titik ieu, mikroskop akustik scanning nunjukkeun kaunggulan khusus na dina deteksi nondestruktif PCB kapadetan tinggi multi lapisan. The general obvious bursting plate can be detected by visual inspection.

5. Analisis mikroinfrared

Analisis mikro inframerah nyaéta spéktroskopi infra merah digabungkeun sareng metode analisa mikroskop, éta ngagunakeun bahan anu béda (utamina bahan organik) dina prinsip nyerep spéktrum infra merah, nganalisis komposisi senyawa bahan, ditambah ku mikroskop tiasa ngajantenkeun lampu anu terang sareng cahaya infra merah kalayan jalur lampu, salami handapeun lapangan visual, tiasa milari analisis polutan organik tilas. Upami henteu aya mikroskop, spéktroskopi infra red biasana nganalisis ngan ukur sampel ageung. 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. Analisis mikroskop éléktron

Mikroskop éléktron éléktron (SEM) mangrupikeun salah sahiji sistem pencitraan mikroskopis éléktron skala pang gunana pikeun analisis kagagalan. Prinsip kerjina nyaéta ngawangun sinar éléktron kalayan diaméter puluhan dugi rébuan angstrom (A) ku museurkeun sinar éléktron anu dipancarkeun tina katoda anu digancangan ku anoda. Dina peta deflection tina scanning coil, Sinar éléktron nyeken permukaan titik sampel ku titik dina urutan waktos sareng ruang anu tangtu. Sinar éléktron énergi tinggi ngabom permukaan sampel sareng ngahasilkeun rupa-rupa inpormasi, anu tiasa dikumpulkeun sareng dikuatkeun pikeun kéngingkeun sababaraha rupa grafik anu saluyu dina layar tampilan. 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. Éléktron backscattered bungah dihasilkeun dina kisaran 100 ~ 1000nm dina permukaan sampel, sareng éta ngaluarkeun ciri anu bénten-bénten sareng bédana jumlah atom zat. Ku alatan éta, gambar éléktron backscattered ngagaduhan ciri morfologis sareng kamampuan diskriminasi jumlah atom, ku sabab éta, gambar éléktron backscattered tiasa ngagambarkeun distribusi unsur kimia. Mikroskop éléktron scanning ayeuna parantos kuat pisan, naon waé struktur anu hadé atanapi fitur permukaan tiasa digedékeun janten ratusan rébu kali pikeun pangamatan sareng analisis.

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. Salaku tambahan, jero lapangan gambar mikroskop éléktron scanning langkung ageung tibatan mikroskop optik, anu mangrupikeun cara anu penting pikeun analisa struktur metallographic, patah mikroskopis sareng kumis timah.

7. X-ray energy spectrum analysis

Mikroskop éléktron éléktron anu disebut di luhur biasana dilengkepan ku spéktrométer énergi sinar-X. 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. Dina waktos anu sami, instrumén anu pakait masing-masing disebat spéktrométer dispersi spéktrum (WDS pikeun pondok) sareng spéktrometer dispersi énergi (EDS pikeun pondok) numutkeun panjang gelombang karakteristik atanapi énergi karakteristik tina deteksi sinyal sinar-X. Resolusi spéktrométer langkung luhur tibatan spéktrométer énergi, sareng laju analisis spéktrométer énergi langkung gancang tibatan spéktrométer énergi. Kusabab kagancangan sareng béaya rendah spéktrométer énergi, mikroskop éléktron SCANNING umum dilengkepan spéktrométer énergi.

Kalayan modeu scanning balok éléktron anu béda, spéktrométer énergi tiasa nganalisis titik, garis sareng bidang permukaan, sareng kéngingkeun inpormasi sebaran unsur anu béda.Point analysis yields all elements of a point; Analisis garis Salasahiji analisa elemen dilakukeun dina garis anu parantos ditangtoskeun unggal waktos, sareng distribusi garis sadaya unsur diala ku sababaraha scanning. Analisis permukaan Analisis sadaya unsur dina permukaan anu ditangtukeun. Eusi unsur anu diukur nyaéta rata-rata kisaran ukuran permukaan.

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. Akurasi analisis kuantitatif spéktrométer énergi diwatesan, sareng konténna kirang ti 0.1% umumna henteu gampang dideteksi. Kombinasi spéktrum énergi sareng SEM tiasa kéngingkeun inpormasi morfologi permukaan sareng komposisi sakaligus, anu janten alesan naha aranjeunna seueur dianggo.

8. Analisis spéktroskopi Photoelectron (XPS)

Sampel ku iradiasi sinar X, permukaan éléktron cangkang jero atom bakal kabur tina beungkeut inti sareng ngabentuk permukaan padet, ngukur énergi kinétik na Ex, éléktron cangkang jero atom tiasa diala énergi anu ngariung Eb, Eb rupa-rupa tina unsur anu béda sareng cangkang éléktron anu béda, éta mangrupikeun “sidik jari” parameter idéntifikasi atom, formasi garis spéktral mangrupikeun spéktroskopi fotoéléktron (XPS). XPS tiasa dianggo pikeun analisis kualitatif sareng kuantitatif unsur dina permukaan leuit (sababaraha nanométer) permukaan sampel. Salaku tambahan, inpormasi ngeunaan kaayaan valénsi kimia unsur tiasa didapet tina pergeseran kimia énergi anu ngabeungkeut. Éta tiasa masihan inpormasi beungkeut antara kaayaan valénsi lapisan permukaan sareng unsur sakurilingna. 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; Multilayer ogé tiasa dianalisis bujur ku stripping ion argon (tingali kasus ieu di handap) kalayan sensitipitas anu jauh langkung ageung tibatan spéktrum énergi (EDS). XPS utamina dianggo dina analisa analisis kualitas palapis PCB, analisis polusi sareng analisis gelar oksidasi, dina raraga nangtoskeun alesan anu jero ngeunaan katahanan anu goréng.

9. Differential Scanning Calorim-etry

Metode ngukur bédana dina input kakuatan antara zat sareng zat référénsi salaku fungsi suhu (atanapi waktos) dina kontrol suhu anu diprogram. 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). Numutkeun hubungan antara deformasi sareng suhu (atanapi waktos), sipat fisikokimia sareng térmodinamik bahan tiasa dikaji sareng dianalisis. TMA seueur dianggo dina analisis PCB sareng utamina dianggo dina ngukur dua parameter anu paling kritis dina PCB: koefisien ékspansi liniér sareng suhu transisi kaca. PCB kalayan koefisien ékspansi anu ageung teuing bakal sering ngakibatkeun gagalna liang tina logam tina las saatos dipasang sareng dirakit.