As the carrier of various components and the hub of circuit signal transmission, PCB 已成為電子信息產品中最重要、最關鍵的部分，其質量和可靠性水平決定了整個設備的質量和可靠性。 然而，由於成本和技術原因，PCB生產和應用中存在很多故障問題。

對於這種失效問題，我們需要使用一些常用的失效分析技術來保證PCB在製造過程中的質量和可靠性水平。 本文總結了十種失效分析技術以供參考。

PCB故障機理及原因分析

1. 目視檢查

外觀檢查是用肉眼檢查或使用一些簡單的儀器，如立體顯微鏡、金相顯微鏡甚至放大鏡，檢查PCB的外觀，找出不合格的零件和相關物證。 主要作用是定位故障，初步判斷PCB的故障模式。 外觀檢查主要檢查PCB污染、腐蝕、電路板爆炸的位置、電路佈線和故障的規律性，是批量還是個別，是否總是集中在某個區域等。 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 射線透視

對於一些外觀無法檢測的部分，以及PCB內部通孔等內部缺陷，我們必須使用X射線透視系統進行檢查。 X射線透視系統是利用不同材料厚度或不同材料密度的X射線吸濕性或透射率不同的原理來成像的。 該技術更多用於檢查PCBA焊點缺陷位置、通孔缺陷以及高密度封裝的BGA或CSP器件缺陷。 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. 截面分析

切片分析是通過取樣、Mosaic、切片、拋光、腐蝕、觀察等一系列方法和步驟獲得PCB橫截面結構的過程。 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; 同時，對樣品的方法要求高，樣品製備時間也長，需要經過培訓的技術人員才能完成。 For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. 掃描聲學顯微鏡

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. 至此，掃描聲學顯微鏡在多層高密度PCB無損檢測中顯示出其特殊的優勢。 The general obvious bursting plate can be detected by visual inspection.

5. 微紅外分析

顯微紅外分析是將紅外光譜結合顯微鏡分析的方法，它利用不同物質（主要是有機物）的紅外光譜吸收原理，分析物質的化合物成分，再加上顯微鏡可以使可見光和紅外光有了光路，只要在視野下，就可以尋找分析微量有機污染物。 在沒有顯微鏡的情況下，紅外光譜通常只能分析大樣品。 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. 掃描電鏡分析

掃描電子顯微鏡 (SEM) 是用於故障分析的最有用的大型電子顯微成像系統之一。 其工作原理是將陰極發射的電子束經陽極加速後聚焦，形成直徑為數十至數千埃（A）的電子束。 在掃描線圈偏轉的作用下， 電子束按一定的時間和空間順序逐點掃描樣品表面。 高能電子束轟擊樣品表面，產生多種信息，經過採集放大，在顯示屏上得到各種相應的圖形。 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. 激發後的背散射電子在樣品表面產生100～1000nm範圍內的電子，隨著物質原子序數的不同，發射出不同的特性。 因此，背散射電子圖像具有形態特徵和原子序數辨別能力，因此，背散射電子圖像可以反映化學元素的分佈。 現在的掃描電子顯微鏡已經非常強大了，任何細微的結構或表面特徵都可以放大到數十萬倍進行觀察和分析。

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. 此外，掃描電鏡圖像的景深遠大於光學顯微鏡，是分析金相組織、顯微斷口和錫須的重要方法。

7. X-ray energy spectrum analysis

上述掃描電子顯微鏡通常配備有X射線能譜儀。 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. 同時，相應的儀器根據X射線信號檢測的特徵波長或特徵能量分別稱為光譜色散光譜儀（簡稱WDS）和能量色散光譜儀（簡稱EDS）。 光譜儀的分辨率比能譜儀高，能譜儀的分析速度比能譜儀快。 由於能譜儀速度快、成本低，一般的掃描電鏡都配備能譜儀。

能譜儀通過不同的電子束掃描方式，可以對錶面的點、線、面進行分析，獲得不同元素分佈的信息。Point analysis yields all elements of a point; 線分析 每次對指定的線進行一個元素分析，通過多次掃描得到所有元素的線分佈。 表面分析 對給定表面中所有元素的分析。 測量的元素含量是表面測量範圍的平均值。

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. 能譜儀定量分析精度有限，含量低於0.1%一般不易檢測。 能譜和掃描電鏡結合可以同時獲得表面形貌和成分的信息，這也是它們被廣泛使用的原因。

8. 光電子能譜 (XPS) 分析

樣品經X射線照射，原子內殼層電子表面會脫離原子核與固體表面形成的束縛，測量其動能Ex，可得到原子內殼層電子的結合能Eb、Eb 因不同元素和不同電子殼層而異，它是原子識別參數的“指紋”，譜線的形成就是光電子能譜（XPS）。 XPS可用於樣品表面淺表層（幾納米）元素的定性和定量分析。 此外，可以從結合能的化學位移獲得有關元素化學價態的信息。 它可以給出表面層的價態與周圍元素之間的鍵合信息。 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; 多層膜也可以通過氬離子剝離（見下面的案例）進行縱向分析，其靈敏度遠高於能譜 (EDS)。 XPS主要用於PCB塗層質量分析、污染分析和氧化程度分析，以確定可焊性差的深層原因。

9. Differential Scanning Calorim-etry

一種在程序溫度控制下測量物質和參比物質之間功率輸入差異作為溫度（或時間）函數的方法。 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. 膨脹係數過大的PCB在焊接組裝後，往往會導致金屬化孔的斷裂失效。