Commom Quality Issues of SMT Processing and Solutions

2017-12-29 18:38:34 viya 141

Quality IssuesSolutions

Gluing Process
Gluing wire/spillover
Revise the gluing process parameters;
Control the amount of gluing;
Adjust the process parameters of SMT patch;
Plugging of glue mouth
Empty gluing
Components displacement
Components lost after waving soldering
Fixed components pins are flost or shift

SMT Soldering Quality Defective
TombstoneChange the pad design and layout.
Select higher activity of solder paste;improve the solder paste printing parameters,especially the hole size of the stencil
Adjust the processing parameters of the SMT Machine
Adjust the approprite temperature curve according to each different product
Solder JointAttention to the heating rate and take a moderate preheat and provide a good platform to make the most of the solvent volatilization
Flying solder jointSelect the high quality solder paste, and pay attention to the storage and use of solder paste
Solder BridgeAdjust the proportioning of solder paste or use a good quality solder paste
Printing machine has poor repeatability and uneven alignmentAdjust the printing press and improve the coating layer of PCB welding disk

Wave Soldering Quality Defective
Solder icicleAdjust the transmission speed to the right place, adjust the preheating and tin pot temperature, revise the PCB transmission angle, optimize the nozzle, regulate the wave shape, change the next flux and solve the weldability problem of the lead
Solder shortSolve the weldability of the lead, adjust the preheating temperature, test the tin and impurity content of solder, revise the flux density, reduce the hole of the pad, eliminate the oxide of PCB, clean the panel, adjust the transmission speed and adjust the temperature of the tin pot
Insufficient solderSolve the weldability of the lead, reduce the pads and pads holes in the design, reduce the welding angle, adjust the transmission speed,the tin pot temperature, check the pre coating flux device and test the solder content.
Missing solderSolve the weldability of the lead, check the wave crest device, replace the flux, check the pre coating flux device, solve the PCB solderability (cleaning or return), check and adjust the transmission device, use the flux together, and adjust the technological process.
Blistering of solder film after welding
Strictly control of each production link, the purchased PCB should be checked before sending to storage, usually PCB in the temperature of 260℃ should not appear in the 10s bubble phenomenon
PCB should be stored in a ventilated and dry environment with a storage period of not more than 6 months.
PCB should be pre-baked in a oven at 120℃ for 4 hours before welding
The preheating temperature in wave soldering shall be strictly controlled, and it should reach 100~140 degrees before the wave soldering. If the water containing flux is used, the preheating temperature should reach 110~145 degrees.



TAG:   SMT

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