As the carrier of various components and the hub of circuit signal transmission, PCB wis dadi bagean paling penting lan penting ing produk informasi elektronik, level kualitas lan kehandalan nemtokake kualitas lan kehandalan kabeh peralatan. Nanging, amarga biaya lan alasan teknis, ana akeh masalah kegagalan ing produksi lan aplikasi PCB.

Kanggo masalah kegagalan, kita kudu nggunakake sawetara teknik analisis kegagalan sing umum digunakake kanggo njamin level kualitas lan kehandalan PCB ing pabrik. Makalah iki ngringkes sepuluh teknik analisis kegagalan kanggo referensi.

Mekanisme lan analisis analisis kegagalan PCB

1. Pengawasan visual

Inspeksi tampilan yaiku mriksa utawa nggunakake visual sawetara instrumen sing gampang, kayata mikroskop stereoskopik, mikroskop metallographic utawa kaca pembesar, kanggo mriksa tampilan PCB lan nemokake bagean sing gagal lan bukti fisik sing relevan. Fungsi utamane yaiku nemokake kegagalan lan sadurunge mbiji mode kegagalan PCB. Pemeriksaan tampilan utamane mriksa polusi PCB, korosi, lokasi jeblugan papan, kabel sirkuit lan rutinitas kegagalan, yen akeh utawa individu, apa mesthi dikonsentrasi ing wilayah tartamtu, lsp. 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 sawetara bagean sing ora bisa diawasi saka tampilan, uga ing njero PCB liwat bolongan lan cacat internal liyane, kita kudu nggunakake sistem fluoroskopi sinar-X kanggo mriksa. Sistem fluoroskopi sinar-X yaiku nggunakake kekandelan materi sing beda-beda utawa kepadatan materi beda-beda hibroskopisitas sinar-X utawa transmisi prinsip sing beda kanggo pencitraan. Teknologi iki luwih digunakake kanggo mriksa lokasi cacat ing sendi solder PCBA, liwat cacat bolongan lan cacat piranti BGA utawa CSP kanthi kemasan kerapatan 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 bagean

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; Sanalika, cara syarat sampel dhuwur, wektu persiapan sampel uga dawa, kebutuhan kanggo tenaga teknis sing wis trampil rampung. For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. Mindhai 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. Ing titik iki, mikroskop akustik pindai nuduhake kaluwihan khusus ing deteksi nondestruktif PCB kerapatan tinggi multi-lapisan. The general obvious bursting plate can be detected by visual inspection.

5. Analisis mikroinfrared

Analisis inframerah mikro yaiku spektroskopi inframerah sing dikombinasikake karo metode analisis mikroskop, nggunakake macem-macem bahan (umume bahan organik) ing prinsip penyerapan spektrum inframerah, nganalisa komposisi senyawa bahan, ditambah karo mikroskop bisa nggawe cahya sing katon lan cahya infra merah kanthi jalur cahya, anggere ing sangisore lapangan visual, bisa digoleki analisis polutan organik tilak. Tanpa mikroskop, spektroskopi inframerah biasane mung bisa nganalisa conto gedhe. 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 elektron

Mikroskop elektron (SEM) minangka salah sawijining sistem pencitraan mikroskopis skala gedhe sing migunani kanggo analisis kegagalan. Prinsip kerjane yaiku mbentuk balok elektron kanthi diameter puluhan nganti ewonan angstrom (A) kanthi fokus balok elektron sing dipancarake saka katod sing digawe cepet dening anoda. Ing tumindak defleksi koil pemindaian, Sinar elektron mindai permukaan titik sampel kanthi titik ing urutan wektu lan ruang tartamtu. Sinar elektron energi tinggi ngepung permukaan sampel lan ngasilake macem-macem informasi, sing bisa dikumpulake lan ditambah kanggo entuk macem-macem grafis sing cocog ing 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. Elektron backscatter sing nyenengake digawe ing kisaran 100 ~ 1000nm ing permukaan sampel, lan ngetokake macem-macem karakteristik kanthi bedane jumlah atom zat kasebut. Mula, gambar elektron backscattered nduweni ciri morfologis lan kemampuan diskriminasi nomer atom, mula saka iku, gambar elektron backscattered bisa nggambarake distribusi unsur kimia. Mikroskop elektron pemindaian saiki kuat banget, struktur utawa fitur permukaan sing apik bisa ditambah nganti atusan ewu kali kanggo pengamatan lan 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. Kajaba iku, ambane bidang gambar mikroskop elektron scanning luwih gedhe tinimbang mikroskop optik, sing minangka metode penting kanggo analisis struktur metallographic, patah mikroskopik lan kumis timah.

7. X-ray energy spectrum analysis

Mikroskop elektron pemindaian ing ndhuwur biasane dilengkapi spektrometer energi 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. Ing wektu sing padha, instrumen sing cocog diarani spektromsi dispersi spektrum (cendhak WDS) lan spektromsi dispersi energi (EDS cekak) miturut dawa gelombang karakteristik utawa energi karakteristik saka deteksi sinyal sinar-X. Resolusi spektrometer luwih dhuwur tinimbang spektrometer energi, lan kecepatan analisis spektrometer energi luwih cepet tinimbang spektrometer energi. Amarga spektrometer energi kanthi kecepatan dhuwur lan murah, mikroskop elektron SCANNING umum dilengkapi spektrometer energi.

Kanthi mode pemindaian sinar elektron sing beda, spektrometer energi bisa nganalisis titik, garis lan bidang ing ndhuwur, lan entuk informasi babagan distribusi unsur sing beda.Point analysis yields all elements of a point; Analisis baris Siji analisis elemen ditindakake ing baris sing ditemtokake saben-saben, lan distribusi garis kabeh elemen dipikolehi kanthi sawetara pemindaian. Analisis permukaan Analisis kabeh elemen ing permukaan tartamtu. Isi unsur sing diukur yaiku rata-rata kisaran pangukuran 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 spektrometer energi diwatesi, lan konten sing kurang saka 0.1% umume ora gampang dideteksi. Kombinasi spektrum energi lan SEM bisa entuk informasi morfologi lan komposisi permukaan kanthi bebarengan, dadi sebab kenapa akeh digunakake.

8. Analisis spektroskopi Photoelectron (XPS)

Sampel kanthi iradiasi sinar X, lumahing elektron cangkang njero atom bakal uwal saka ikatan inti lan bentuk permukaan padhet, ngukur energi kinetik yaiku Ex, elektron cangkang njero atom bisa dipikolehi energi pengikatan Eb, Eb beda-beda saka macem-macem elemen lan cangkang elektron sing beda, minangka “sidik jari” paramèter idhentifikasi atom, pambentukan garis spektral yaiku spektroskopi fotoelektron (XPS). XPS bisa digunakake kanggo analisis kualitatif lan kuantitatif unsur ing permukaan cethek (sawetara nanometers) saka permukaan sampel. Kajaba iku, informasi babagan unsur valensi kimia saka unsur bisa dipikolehi saka owah-owahan kimia energi naleni. Bisa menehi informasi ikatan antarane kahanan valence saka lapisan permukaan lan unsur sekitare. 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 uga bisa dianalisis kanthi longitudinal kanthi stripping ion argon (waca kasus ing ngisor iki) kanthi sensitivitas sing luwih gedhe tinimbang spektrum energi (EDS). XPS umume digunakake ing analisis analisis kualitas lapisan PCB, analisis polusi lan analisis derajat oksidasi, kanggo nemtokake alasan jero las sing kurang.

9. Differential Scanning Calorim-etry

Cara ngukur prabédan input daya antarane zat lan zat referensi minangka fungsi suhu (utawa wektu) ing kontrol suhu sing wis 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). 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 kanthi koefisien ekspansi sing gedhe banget asring bakal nyebabake gagal bolongan metallized sawise welding lan assembling.