PCB Blogger-China PCB Factory,HOYOGO

       In   the SMT processing process, sometimes there will be defects such as misalignment and bridging.   If such defects occur, the PCB needs to be reworked and repaired.  So what are the requirements for the   rework and   repair  technology   of  bad   SMT?       1.  Operators should wear anti-static wrist straps or bracelets.     2. It is generally required to use an anti-static constant temperature electric soldering iron.  If you use a common electric soldering iron, the ground must be good.     3. When repairing chip components, a 15-20W low-power electric soldering iron should be used, and the temperature of the soldering iron tip should be controlled below 250 ℃ .     4. The soldering time should not be too long, otherwise it is easy to burn out the components. soldering times of the same solder joint  shall not   exceed two times.     5.  Solder joints should be in the shape of sine wave peaks, the surface should be bright and smooth, without tin thorns, and the amount of

  Usually, after reflow soldering, the yield rate of PCB cannot reach 100%, and some defects will appear more or less.   Among these defects, some are surface defects, which only affect the surface appearance of solder joints, but do not affect the function and life of the product. However, some defects will seriously affect the function and life of the product, such as: misalignment, bridge connection, etc. Such defects must be reworked and repaired. Do you know any skills for reworking and repairing bad SMT?       1. Manual rework and repair and soldering should follow the principle of SMT components first small and then large, first low and then high. First solder chip resistors, chip capacitors, transistors, then solder small IC devices, large IC devices, and finally solder plug-ins.     2. When soldering chip components, the width of the soldering bit should be consistent with the width of the components. If it is too small, it will not be easy to position when soldering.     3. 

       Automotive PCB refers to the PCB used in automotive electronic systems.   Automotive electronic systems are becoming more and more popular, so the market demand for PCB manufacturers'  automotive PCB   is also increasing.  They are widely used in many electronic devices and systems of automobiles, including engine control systems, in-vehicle entertainment systems, dashboards, navigation systems, airbag systems, braking systems, etc.  So why choose automotive PCB? Instead of choosing a normal PCB?     1.   Good  H igh   T emperature  R esistance Because the temperature inside the car is higher than outside, the PCB need to have better high temperature resistance. If you use an ordinary PCB, it may not be able to withstand the high temperature environment, resulting in circuit failure. The high temperature resistance of automotive PCB can reach above 150 ° C, so can meet the needs of the automotive industry.     2.  Good  V ibration  R esistance Because the vehicle will experi

       In SMT processing, SMT adhesive is one of the important production raw materials. Before wave soldering, the PCBA factory needs to use SMT adhesive to fix the mounted components on the corresponding position of the PCB, so as to prevent the components from falling into the tin pot during wave soldering.  So what are the requirements for SMT adhesives in SMT processing?       1.  The service life is longer at room temperature.     2.  Suitable viscosity. The viscosity of the SMT adhesive should be able to meet the needs of different sizing methods, different equipment, and different sizing temperatures. There should be no wire drawing when dispensing glue. It can maintain enough height after coating without forming too much rubber base. After coating and before curing, the drips should not flow, so as not to reach the welding part and affect the welding quality.     3.  F ast curing . The  SMT  adhesive should be cured at the fastest speed at the lowest possible temperature.  Thi

       The copper  base PCB   is  mainly  based on  copper, and its composition  structure   are  the same as that of the aluminum  PCB , which are the copper base layer, the insulating layer and the circuit layer. 1. The circuit layer of the copper base PCB is required to have a large current carrying capacity, so thicker copper foil should be used.     2. The insulating layer is the core technology of the copper base PCB. The composition is composed of aluminum oxide and silicon powder and epoxy resin filled polymer.  It has low thermal resistance, excellent viscoelasticity, thermal aging resistance, and can withstand mechanical and thermal stress.     3. The metal base layer is the support member of the copper base PCB, which requires high thermal conductivity and is suitable for conventional machining such as drilling, punching and cutting.     4. Copper  base PCB  can be machined into metallized holes, but aluminum  PCB  cannot.  The network of metallized holes must be the same ne

       The impedance control circuit of the  rigid-flex board  is also called t he impedance strip .  When the current that needs to pass through the  circuit  is greater than the maximum value that the  circuit  can withstand, it is necessary to use impedance to control the excess current, which is the principle of impedance control.  Many aspects will affect the resistance value of the impedance line, do you know any aspects?       1.  Different substrates lead to different impedance values The difference of the substrate material has a great influence on the  flexible   board.   Not only the resistance value of each material is different, but even in the case of the same material, the resistance value of each part will not be exactly the same, just as there are no two  same   leaves in the world.   The impedance circuit on the impedance board generally uses a substrate with good material stability.  If the material with poor stability is used, when the resistance value of the materi

      Before leaving the PCB factory, PCB will pass electrical testing to ensure that the PCB has high performance and high reliability in the final product. Flying probe test is one of the more effective test methods, so what are its advantages and disadvantages?       Advantages: 1.  Shorter test development cycles. The system  can  start production  within  a few  hours  after  rece iving the  CAD files, so prototype boards can be tested  several  hours after assembly.     2.  Lower test costs. There is no need to make special test fixtures.     3. Due to the simp le  and fast  of  setting, programming and testing, general technical assembly personnel can perform operational testing.     4.  Higher test accuracy.  The positioning accuracy and repeatability of the online testing of the flying probe, as well as a very small contact and spacing, so that the test system can detect the PCB node that the needle bed fixture cannot achieve.     Disadvantages: 1. As the test probes make phys