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Double-sided pcb basic manufacturing process and testing

365 Published by FASTPCBA 4月 22,2019

Double-sided pcb basic manufacturing process and testing

PCBA craft process 

Double-sided pcb craft process is very complicated, basically going through nearly 50 processes, from circuit board process, component procurement and inspection, SMT patch assembly, DIP plug-in, PCBA test, program firing, packaging and other important processes. Among them, the circuit board process has 20 to 30 processes, and the program is extremely complicated. The PCBA process flow is shown in detail in the figure below, allowing you to quickly acquire relevant expertise.

PCBA craft process flow chart

double-sided pcb

Circuit board processing technology and equipment

Circuit board equipment includes electroplating wire, copper wire, DES wire, SES wire, washing machine, OSP wire, nickel-plated gold wire, press, exposure machine, oven, AOI, plate warping machine, edger, cutting material Machine, vacuum packaging machine, gone machine, drilling machine, air compressor, tin spray machine, CMI series, photoplotter, etc.

The board can be divided into single-sided pcb, double-sided pcb and multi-layer pcb according to the number of layers of the conductor pattern. The basic manufacturing process of a single panel is as follows.

Foil–>Unloading–>Bake-up (preventing deformation)–>Molding–>Washing, drying–>Foil (or screen printing)->Exposure development (or anti-corrosion ink) – -> Etching -> De-filming —> Electrical continuity detection –> Cleaning treatment –> Screen printing resistance welding pattern (printed green oil) –> curing –> screen printing symbol –> curing – ->Drilling –> Shape processing –> cleaning and drying –> inspection –> packaging –> finished products.

 

The basic manufacturing craft process of the double-sided PCB is as follows:

Graphic plating craft process

Foil–>Unloading–>Drilling Datum Hole–>CNC Drilling–>Inspection–>Deburring–>Chemical Plating Copper–>Electroplating Thin Copper–>Inspection–> Brush plate –> film (or screen printing) –> exposure development (or curing) –> Inspection and repair board —> pattern plating (Cn ten Sn / Pb) –> remove film –> etching – ->Inspection and repair board–>Plug nickel plating gold plating–>Hot melt cleaning–>Electrical continuity test–>Cleaningtreatment–>Screen printing resistance pattern–>Cure–>Screen printing symbol- -> Curing -> Shape Processing -> Cleaning and Drying -> Inspection -> Packaging -> Finished Product.

 

The main advantage of the bare copper solder mask (SMOBC) process is to solve the solder bridging short circuit between the thin lines, and because of the constant lead-tin ratio, it has better solderability and storage than the hot melt board. The SMOBC process for replating lead-tin by pattern plating is similar to the pattern plating process. Change only after etching. Double-sided pcb copper clad plate–> according to the pattern plating process to the etching process–> lead-free tin–> check—->clean—> solder resist pattern–> plug nickel-plated gold–> Plug tape -> hot air leveling —-> cleaning —> screen printing symbol —> shape processing —> cleaning and drying —> finished product inspection –> packaging –> finished products.

 

SMT mounting processing technology

  1. According to the customer Gerber file and BOM list, make the SMT production craftfile and generate the SMT coordinate file.
  2. Check whether all the production materials are ready, make a complete set, and confirm the PMC plan for production.
  3. Perform SMT programming and make the first board for verification to ensure correctness.
  4. According to the SMT process, make laser steel mesh

5.Solder paste printing to ensure uniform solder paste, good thickness and consistency

  1. Mount the components on the circuit board through the SMT placement machine, and perform online AOI automatic optical inspection if necessary.
  2. Set the perfect reflow soldering furnace temperature curve, let the circuit board flow through reflow soldering, solder paste from paste, liquid to solid state, after cooling, good welding can be achieved.
  3. After the necessary IPQC check
  4. The DIP plug-in process passes the plug-in material through the board and then flows through the wave soldering for soldering.
  5. Necessary post-furnace craftsuch as shearing, post-welding, board cleaning, etc.

11.QA conducts overall testing to ensure quality is OK

Double-sided pcb

double-sided pcb

PCBA test

PCBA tests is the most critical quality control link in the entire PCBA processing process. It is necessary to strictly follow the PCBA test standards and test the test points of the board according to the customer’s test plan.

The PCBA test also includes five main forms: ICT test, FCT test, burn-in test, fatigue test, and test in harsh environments. The ICT (In Circuit Test) test mainly includes the circuit’s on-off, voltage and current values and fluctuation curves, amplitude, noise, etc.; and the FCT (Functional Circuit Test) test requires IC program firing, the function of the entire PCBA board. Perform simulation tests to identify problems in hardware and software, and equip with the necessary production fixtures and test stands;

Aging test is mainly to energize the PCBA board and electronic products for a long time, keep their work and observe whether there is any failure. After the aging test, the electronic products can be sold in batches; the fatigue test is mainly for the PCBA board sampling, and performing high-frequency, long-term operation of the function, to observe whether there is a failure, such as continuous click of the mouse up to 100,000 times or turn LED lights on and off for 10,000 times, test the probability of failure, in order to feedback the PCBA board in the electronic product Work performance; the test under the Severe Conditions is mainly to expose the PCBA board to the limit temperature, humidity, drop, splash, vibration, and obtain the test result of the random sample, thereby inferring the reliability of entire PCBA board batch product.

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