国产精品福利一区二区,精品国产免费人成电影在线看,久久精品亚洲国产,激情综合色综合啪啪五月丁香,中文毛片无遮挡高潮免费,成在人线AV无码免费高潮喷水,黄A无码片内射无码视频,无码视频一区二区三区,成AV免费大片黄在线观看,丁香色婷婷国产精品视频

      Welcome to the official website of Legret Metal Company
      Focus on electronic welding for 20 yearsDONGGUAN LEGRET METAL.,LTD
      National consultation hotline:135-2799-2739
      Contact US
      mobile phone: 135-2799-2739
      Service hotline: 0769-38893080
      Email: lzd@dglzd.com
      Address: Dongguan lvzhidao Metal Co., Ltd
      Contact person: Manager Zeng
      Industry information

      What should be paid attention to when using reflow solder paste? In the process of reflow soldering, what kind of change will happen?

      作者:Lvzhidao solder factory 2021-03-02 0

      What should be paid attention to when using reflow soldering? In the process of reflow soldering, what kind of change will happen?


      1、 When the solder paste reaches the heating zone, the temperature begins to rise. The temperature rise must be slow (about 2 ℃ ~ 3 ℃ per second) to prevent boiling and splashing and to avoid the formation of small solder beads; Some components are sensitive to internal stress, which may cause fracture when the external temperature of components rises too fast( At this time, the solvent used to improve the screen printing performance and viscosity of solder paste begins to evaporate.)


      2、 The flux inside the solder paste starts to be active, and the chemical cleaning action begins. The same cleaning action will take place for both water-soluble flux and free cleaning flux, but the temperature required to start the action is slightly different( At this time, the chemical cleaning action will remove the metal oxide and some contamination from the solder particles and metal to ensure that the metallurgical requirements of the "clean" solder joint surface are met


      3、 When the temperature in reflow soldering furnace continues to rise, a single solder particle begins to melt, liquefy and absorb tin on the surface. In this way, all the surfaces that may be covered begin to cover and solder spots gradually form.


      4、 This stage is the most important in reflow soldering. When all the individual solder particles are melted and combined with the liquid tin formed due to high temperature, the surface of solder pin begins to form under the action of surface tension. If the gap between component pin and PCB pad exceeds 0.1mm, the pin and pad may be separated under the action of surface tension, As a result, the solder joint is open.


      5、 When the solder joint formed by solder paste enters the cooling zone, the solder joint begins to cool. If the cooling speed is a little faster, the strength of the solder joint will increase, but it should not be cooled too fast, otherwise it will cause the internal temperature stress of the component.




      欧美精品一区二区精品久久| 男人J桶进女人P无遮挡全过程| 日韩欧美在线视频一区二区| 狠狠综合亚洲综合亚洲色| 男女后式激烈动态图片| 国产情侣大量精品视频| 娇妻被别人带去杂交| 97人摸人人澡人人人超一碰| 色8激情欧美成人久久综合电| 亚洲精品有码在线观看| 少妇人妻AV毛片在线看| 99久久久无码国产精品古装| 欧美精品欧美人与动人物牲交| 99视频精品全部国产盗摄视频| 亚洲国产资源| 在线观看精品视频一区二区| 香蕉久久成人国产精品免费| 亚洲国产精品综合久久网各| 国产区第一页| 国内精品久久久久久网站| 国产成人亚洲精品另类动态| 日韩精品女同一区二区三区| 欧美日韩三级| 北条麻妃一区二区三区av高清| 欧美黑人巨大videos精品| 国产一区二区内射最近更新| www亚洲精品久久久乳| 青青草原成年网站免费观看 | 成 人 网 站 在 线 观看| 国产精品美女午夜爽爽爽免费| 国产精品成熟老妇女| 亚洲AV无码国产精品麻豆天美| 疯狂撞击丝袜人妻| 18禁又大又黄| 国产成人亚洲精品无码h在线| 男女性高爱潮免费网站| 亚洲国产精品久久久久秋霞小| 久久精品国产99久久久古代 | 亚洲熟妇无码一区二区三区导航| 免费 无码 国产在线| 亚洲国产精品成人久久蜜臀|