SMT的特點(diǎn)
The characteristics of SMT
組裝密度高、電子產(chǎn)品體積小、重量輕，貼片元件的體積和重量只有傳統(tǒng)插裝元件的1/10左右，一般采用SMT之后，電子產(chǎn)品體積縮40%~60%，重量減輕60%~80%。
The assembly density is high, the electronic product is small, and the weight is light. The volume and weight of the patch element are only about 1/10 of the traditional cartridge element. After SMT, the volume of the electronic product is 40%~60% and the weight is reduced to 60%~80%.
可靠性高、抗振能力強(qiáng)。焊點(diǎn)缺陷率低。
High reliability and strong anti vibration ability. The defect rate of solder joints is low.
高頻特性好。減少了電磁和射頻干擾。
High frequency characteristics. It reduces electromagnetic and radio frequency interference.
易于實(shí)現(xiàn)自動(dòng)化，提高生產(chǎn)效率。降低成本達(dá)30%~50%。 節(jié)省材料、能源、設(shè)備、人力、時(shí)間等。
It is easy to realize automation and improve production efficiency. The cost is reduced to 30%~50%. Save materials, energy, equipment, manpower, time and so on.
為什么要用表面貼裝技術(shù)(SMT)？
Why do we use surface mount technology (SMT)?
電子產(chǎn)品追求小型化，以前使用的穿孔插件元件已無(wú)法縮小，電子產(chǎn)品功能更完整，所采用的集成電路(IC)已無(wú)穿孔元件，特別是大規(guī)模、高集成IC，不得不采用表面貼片元件產(chǎn)品批量化，生產(chǎn)自動(dòng)化，廠方要以低成本高產(chǎn)量，出產(chǎn)優(yōu)質(zhì)產(chǎn)品以迎合顧客需求及加強(qiáng)市場(chǎng)競(jìng)爭(zhēng)力。
In pursuit of miniaturization of electronic products, the perforated plug-in components used previously can not be reduced and the electronic products have more complete functions. The integrated circuits (IC) used have no perforated components, especially large scale and high integrated IC, and have to use surface patch components to batch products, produce automation, and produce high output with low cost. Produce high quality products to cater to the needs of customers and enhance market competitiveness.
電子元件的發(fā)展，集成電路(IC)的開發(fā)，半導(dǎo)體材料的多元應(yīng)用，
The development of electronic components, the development of integrated circuits (IC), the multiple applications of semiconductor materials,
電子科技革命勢(shì)在必行，追逐國(guó)際潮流。
The revolution of electronic technology is imperative and the pursuit of international trends.
為什么在表面貼裝技術(shù)中應(yīng)用免清洗流程？
Why do we apply the no cleaning process in surface mount technology?
生產(chǎn)過(guò)程中產(chǎn)品清洗后排出的廢水，帶來(lái)水質(zhì)、大地以至動(dòng)植物的污染。
In the process of production, the waste water discharged from the product will pollute the water quality, the earth and even plants and animals.
除了水清洗外，應(yīng)用含有氯氟氫的有機(jī)溶劑(CFC&HCFC)作清洗，亦對(duì)空氣、大氣層進(jìn)行污染、破壞。
In addition to water cleaning, the organic solvent (CFC&HCFC) containing chlorine, fluorine and hydrogen is used for cleaning. It also pollute and destroy the air and atmosphere.
清洗劑殘留在機(jī)板上帶來(lái)腐蝕現(xiàn)象，嚴(yán)重影響產(chǎn)品質(zhì)素。
The cleaning agent remains on the machine plate to cause corrosion and seriously affect the quality of the product.
減低清洗工序操作及機(jī)器保養(yǎng)成本。
Reduce the operation and maintenance cost of the cleaning process.
免清洗可減少組板(PCBA)在移動(dòng)與清洗過(guò)程中造成的傷害。仍有部分元件不堪清洗。
No cleaning can reduce the damage caused by PCBA during movement and cleaning. Some of the components are still unbearable.
助焊劑殘留量已受控制，能配合產(chǎn)品外觀要求使用，避免目視檢查清潔狀態(tài)的問(wèn)題。
The flux residue has been controlled, which can match the appearance requirements of the product and avoid the problem of visual inspection of cleanliness.
殘留的助焊劑已不斷改良其電氣性能，以避免成品產(chǎn)生漏電，導(dǎo)致任何傷害。
The residual flux has been continuously improving its electrical properties to avoid leakage of the finished product and cause any damage.
免洗流程已通過(guò)國(guó)際上多項(xiàng)安全測(cè)試，證明助焊劑中的化學(xué)物質(zhì)是穩(wěn)定的、無(wú)腐蝕性的。
The washing process has passed many safety tests in the world, proving that the chemicals in flux are stable and non corrosive.
回流焊缺陷分析：
Reflow defect analysis:
錫珠原因：
The cause of tin Zhu:
1、絲印孔與焊盤不對(duì)位，印刷不精確，使錫膏弄臟PCB。
1, silk screen holes and pads are not aligned, printing is not accurate, so that solder paste dirty PCB.
2、錫膏在氧化環(huán)境中暴露過(guò)多、吸空氣中水份太多。
2, solder paste exposes too much in the oxidizing environment and sucks too much water in the air.
3、加熱不精確，太慢并不均勻。
3, the heating is inaccurate, too slow is not uniform.
4、加熱速率太快并預(yù)熱區(qū)間太長(zhǎng)。
4. The heating rate is too fast and the preheating range is too long.
5、錫膏干得太快。
5, the solder paste is too dry.
6、助焊劑活性不夠。
6, the flux of the flux is not enough.
7、太多顆粒小的錫粉。
7, too many small particles of tin powder.
8、回流過(guò)程中助焊劑揮發(fā)性不適當(dāng)。錫球的工藝認(rèn)可標(biāo)準(zhǔn)是：當(dāng)焊盤或印制導(dǎo)線的之間距離為0.13mm時(shí)，錫珠直徑不能超過(guò)0.13mm，或者在600mm平方范圍內(nèi)不能出現(xiàn)超過(guò)五個(gè)錫珠。
8. The flux of flux is not appropriate in the process of reflux. The technical approval of the tin ball is that when the distance between the weld plate or the printed wire is 0.13MM, the diameter of the tin bead can not exceed 0.13MM, or more than five tin beads can not be found in the 600mm square range.
錫橋(Bridging)：一般來(lái)說(shuō)，造成錫橋的因素就是由于錫膏太稀，SMT貼片加工包括 錫膏內(nèi)金屬或固體含量低、搖溶性低、錫膏容易榨開，錫膏顆粒太大、助焊劑表面張力太小。焊盤上太多錫膏，回流溫度峰值太高等。
Tin bridge (Bridging): generally, the cause of the tin bridge is because the solder paste is too thin. The SMT patch processing includes low metal or solid content in the solder paste, low shake solubility, easy extraction of tin paste, too large tin paste particles and small welding flux surface Zhang Litai. There are too many solder paste on the pad, and the peak value of reflux temperature is too high.
開路原因：
Reasons for the opening of the road:
1、錫膏量不夠。
1, the amount of solder paste is not enough.
2、元件引腳的共面性不夠。
2, the component pin's coplanarity is not enough.
3、錫濕不夠(不夠熔化、流動(dòng)性不好)，錫膏太稀引起錫流失。
3, tin wet is not enough (not melting, fluidity is bad), solder paste is too thin to cause tin loss.
4、引腳吸錫(象燈芯草一樣)或附近有連線孔。引腳的共面性對(duì)密間距和超密間距引腳元件特別重要，一個(gè)解決方法是在焊盤上預(yù)先上錫。引腳吸錫可以通過(guò)放慢加熱速度和底面加熱多、上面加熱少來(lái)防止。也可以用一種浸濕速度較慢、活性溫度高的助焊劑或者用一種Sn/Pb不同比例的阻滯熔化的錫膏來(lái)減少引腳吸錫。
4, the pin sucking tin (like rush rush) or near the connection hole. The coplanarity of pins is particularly important for pin spacing and ultra high spacing pin elements. One solution is to pre solder tin on the pad. Pin tin absorption can be prevented by slowing down the heating speed and heating the bottom surface much less. It is also possible to reduce the pin tin absorption by using a slow wetting, high active flux or a solder paste with different proportions of Sn/Pb retarding melting.
SMT有關(guān)的技術(shù)組成
The technical composition of SMT
電子元件、集成電路的設(shè)計(jì)制造技術(shù)
Design and manufacture technology of electronic components and integrated circuits
電子產(chǎn)品的電路設(shè)計(jì)技術(shù)
Circuit design technology of electronic products
電路板的制造技術(shù)
Manufacturing technology of circuit board
自動(dòng)貼裝設(shè)備的設(shè)計(jì)制造技術(shù)
Design and manufacture technology of automatic mounting equipment
電路裝配制造工藝技術(shù)
Circuit assembly manufacturing technology
裝配制造中使用的輔助材料的開發(fā)生產(chǎn)技術(shù)
Development and production technology of auxiliary materials used in assembly manufacturing
程經(jīng)理