Hei kaikawe i nga momo waahanga me te pou o te whakawhiti tohu ara iahiko, PCB kua waiho hei waahanga nui me te waahanga matua o nga hua korero hiko, ko tona kounga me te taumata pono e whakatau ana i te kounga me te pono o nga taputapu katoa. Heoi, na te utu me nga take hangarau, he maha nga raru ngoikore i te hanga PCB me te tono.

Mo tenei momo raru ngoikore, me whakamahi e tatou etahi tikanga wetewete ngoikore e whakamahia ana kia pai ai te kounga me te taumata pono o te PCB mo te mahi hanga. Ka whakarapopototia e tenei pepa nga tikanga wetewete tekau mo te kore korero.

Te miihini me te whakamaarama i te ngoikoretanga PCB

1. He tirotiro tirohanga

Ko te tirohanga kanohi ko te tirotiro kanohi ki te whakamahi i etahi taputapu ngawari ranei, penei i te miihini miihiniiti, te miihini miihini whakarahi, te karaehe whakarakei ranei, hei tirotiro i te ahua o te PCB ka kitea nga waahanga kua rahua me nga taunakitanga a tinana. Ko te mahi matua ko te kimi i te koretake me te whakawa i te aratau rahua o te PCB. Ko te tirotiro i te ahua te nuinga o te tirotiro i te paru PCB, te waikura, te waahi o te pahutanga o te poari, te hiko hiko me te tutukitanga o te rahuatanga, mena he puranga takitahi ranei, ahakoa he mea nui tonu ki tetahi waahi, etc. 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. Haererangi-rama

Mo etahi waahanga kaore e taea te tirotiro e te ahua, me te roto o te PCB na roto i te kohao me etahi atu koha o roto, me whakamahi e tatou te punaha fluoroscopy X-ray hei tirotiro. Ko te punaha fluoroscopy X-ray ko te whakamahi i nga momo matotoru rereke rereke rereke rereke ranei o te X-ray hygroscopicity te whakawhiti ranei i nga kaupapa rereke ki te whakaahua. Ka whakamahia noa ake tenei hangarau hei tirotiro i te waahi o nga koha o nga hononga reima PCBA, na roto i nga kohao o te kohao me nga koha i roto i nga taputapu BGA, i te CSP ranei, he nui te taapara. 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. Takitaki waahanga

Ko te taatai ​​taatai ​​ko te mahi ki te tiki hanganga waahanga whiti PCB na roto i te tauira, i a Mohi, i te poro, i te oro, i te waikura, i te tirohanga me nga tikanga me nga taahiraa. 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; I te wa ano, he tiketike te tikanga o nga whakaritenga tauira, he roa ano te wa whakarite tauira, te hiahia kia oti nga kaimahi hangarau whakangungu. For detailed slicing procedures, please refer to IPC standards IPC-TM-650 2.1.1 and IPC-MS-810.

4. Karapa mokamoka oro

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. I tenei wa, ko te miihini miihini miihini orooro e whakaatu ana i tona painga motuhake mo te kitenga kore-PCB-nui-papanga PCB. The general obvious bursting plate can be detected by visual inspection.

5. Tātari Microinfrared

Ko te wetewete Mōhiohio pōkākā ko te pōharahara pōkākā ka honoa ki te tikanga tātari miihiniiti, ka whakamahia he rauemi rerekē (ko te nuinga o ngā mea waro) i runga i te kaupapa o te mimiti ngongo pōkākā, te wetewete i te kohinga pūhui o ngā rawa, ka honoa ki te karuiti kia kitea te marama me te rama pōkākā. me te ara maama, i nga wa katoa i raro i te papa tirohanga, ka taea te rapu t tari mo nga whakapoke paru koiora. Ki te kore he miihiniiho, ka taea e te spectroscopy pōkākā te wetewete i nga tauira nui noa iho. 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. Te tirotiro i te wetewete miihini hiko

Ko te karapu karawhiu irahiko (SEM) tetahi o nga punaha whakaahua atahanga miihini-a-hiko-whanui mo te wetewete ngoikore. Ko tana kaupapa mahi ko te hanga i te kurupae irahiko me te diameter o te tekau ki te mano nga angstroms (A) ma te tarai i te hihi irahiko i whakaputaina mai i te cathode e whakaterehia ana e te anode. I raro i te mahinga o te kotahitanga o te pōkai karapa, Ka tirohia e te hihi irahiko te mata o te tohu tauira ma te tohu i roto i tetahi waa me te ota waahi. Ko te raima hiko-hiko kaha e pupuhi ana i te mata o te tauira ka whakaputa i nga momo korero, ka taea te kohikohi me te whakakaha kia pai ai nga whakairoiro e hangai ana ki te mata whakaatu. 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. Ko nga hiko i tuaina e koa ana ki te 100 ~ 1000nm kei runga i te mata o te tauira, ka whakaputa i nga ahuatanga rereke me te rereketanga o te ngota ngota o te matū. No reira, ko te ahua irahiko kua whakamutua he ahuatanga morphologic me te aukati tauwehenga tau ngota, na reira, ka taea e te whakaahua irahiko o muri te whakaatu i te tohatoha o nga waahanga matū. He kaha rawa te miihini irirangi karawhiuwhiu, ka taea te whakaniko i nga hanganga pai, i nga waahanga rau ranei ki nga rau rau mano hei tirotiro me te wetewete.

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. Hei taapiri, ko te hohonu o te mara o te karahiko irahuri karu ahua he rahi ake i tera o te miihini whatu, he tikanga nui tenei mo te wetewete i te hanga whakarewa, i te whatiwhatinga me te miihini tiniti.

7. X-ray energy spectrum analysis

Ko te miihini irahiko karawhiu kua whakahuatia i runga ake nei he mea rite ki te miihini hihiko 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. I te wa ano, ko nga mea whakahoahoa e kiia ana ko te spectrometer dispersion spectrum (WDS mo te poto) me te spectrometer dispersion pngao (EDS mo te poto) kia rite ki te roangaru rerekee te kaha o te kaha o te kitenga tohu X-ray ranei. Ko te taumira o te spectrometer he teitei ake i te spectrometer kaha, a ko te tere wetewete o te hihiko hihiko he tere atu i te waahanga o te kaha. Na te tere tere me te iti o te utu mo te spectrometers kaha, ko te miihini irahiko SCANNING whanui kua rite ki nga spectrometers kaha.

Ma te rereketanga o te momo karahiko a te hiko irahiko, ka taea e te maatauhau kaha te wetewete i te tohu, te raina me te papa rererangi o te mata, me te whiwhi korero mo nga rereketanga rereke o nga waahanga.Point analysis yields all elements of a point; Tātari Raina Kotahi te waahanga taatai ​​e mahia ana i runga i te raina kua tohua i ia waa, a ko te tohatoha raina o nga waahanga katoa ka whiwhihia e te matawai maha. Te wetewete i te mata Te wetewete i nga waahanga katoa o te mata i homai. Ko te kohinga huanga whanganga ko te toharite o te awhe o te inenga mata.

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. Ko te tika o te wetewete tika o te spectrometer o te pngao he iti, a ko nga ihirangi iti iho i te 0.1% he ngawari ki te kite. Ko te whakakotahitanga o te hihinga kaha me te SEM ka taea te tiki korero mo te taatai ​​mata me te hanganga i te wa kotahi, koinei te take e whakamahia whanui ai.

8. Tauhokohoko spectroscopy Photoelectron (XPS)

Tauira na te hihi a X, ko te mata o nga irahiko anga o roto o te ngota ka mawhiti mai i te here o te karihi me te mata totoka e hanga ana, e whanganga ana i tona kaha kinetic te Ex, ko nga irahiko anga o roto o te ngota ka taea te whiwhi kaha kaha o Ko te Eb, ko te Eb he rereke mai i nga waahanga rereke me nga anga irahiko rereke, koinei nga “tapumati” o nga tohu tohu ngota, ko te hanganga o te raina spectral ko te phototrectropy spectroscopy (XPS). Ka taea te whakamahi i te XPS mo te taatai ​​me te taatai ​​tauanga o nga waahanga i runga i te papa papaku (he maha nga nanometers) o te waahanga tauira. Hei taapiri, ko nga korero e pa ana ki te noho autaia o te haurangi o nga timatanga ka taea te tiki mai i nga huringa matū o te whakakaha i te kaha. Ka taea te whakaatu i nga korero mo te hononga i waenga i te taahitanga o te paparanga o te paparanga papa me nga waahanga a tawhio noa. 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; Ka taea hoki te wetewete roa i te maha o nga whanui ma te huia o te katote (tirohia te keehi kei raro) me te mohio ake i te kaha o te hihiko (EDS). Ko te XPS e whakamahia ana i roto i te wetewete i te taatai ​​kounga kounga paninga PCB, te taatai ​​parahanga me te taatai ​​tohu tohu waikura, kia pai ai te whakatau i te take hohonu o te ngoikore pai.

9. Differential Scanning Calorim-etry

He tikanga mo te ine i te rereketanga o te whakauru o te hiko i waenga i te matū me te matū tohutoro hei mahi i te pāmahana (te wa ranei) i raro i te mana o te paemahana kua oti te whakamahere. 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)

Whakamahia ai te Hangarau Miihini Ngawha hei ine i nga rereketanga o nga totoka, waipiro me nga pungawerewere i raro i nga mana Mahana, Miihini ranei i raro i te whakahaere o te paemahana. Ko nga tikanga kawenga e whakamahia whanuitia ana ko te pehitanga, te whakauru i te titi, te toro, te piko, me etahi atu. Ko te whakamatau i te whakamatautau kei runga i te kurupae cantilever me te tautoko puna puna, ma te motuka o te kawenga kua whakamahia, ka puta ana te rereketanga o te tauira, te rereketanga rereke hei kite i te panoni, me te tukatuka raraunga, penei i te mahana, te ahotea me te taumaha i muri nga rauemi ka taea te tiki mai i raro i nga hononga whakarereketanga o te kawenga koretake ki te mahana (te waa ranei). E ai ki te hononga i waenga i te rerekee me te mahana (te waa ranei), ka taea te ako me te wetewete i nga momo ahupūngao me te waiariki o ngā rawa. Kei te whakamahia whānuitia a TMA i roto i te wetewete PCB me te nuinga e whakamahia ana ki te mehua i nga waahanga whakahirahira e rua o te PCB: te whakarea whakarea rarangi me te awheawhe whakawhiti karaihe. Ko te PCB me te nui o te whakarea whakarea ka arahi atu ki te ngoikoretanga o nga kohao whakarewa i muri i te hononga me te huihuinga.