Why is there a monument after the PCB is boiled?

Maybe there is a lot of solder paste, the wind is strong, etc.

1.The heat is uneven, and the tin melts first on one side.

2.The solder paste is uneven, and one side is too little.

The reasons for the deformation of the furnace are: the furnace temperature is too high, the thickness of the plate does not match the length and width of the plate, it is too wide and too thin, and it will be deformed after heating, and the board material is also an aspect.

When soldering the PCB board, DXT-398A flux is pre-heated, and then soldered.

In the process of making circuit boards, through hole (professional term, that is, the copper connecting the circuit is plated with chemical and electrochemical methods on the inner wall of the drilled hole) is an important part, and there are many problems, which are not well handled, and bring quality hazards to the later component welding.

During welding, if there is a small amount of water or liquid in the copper layer in the hole, in the high temperature environment, the liquid will vaporize and break through the bondage of the copper layer, forming the appearance of tin being fried. This is a hidden quality hazard left when the circuit board is made.

Yes, because the solder will flow away from the small holes, it is recommended to cover the small holes with green oil! However, you should be a pad handle for the patch, if it is a plug-in, the solder pot will not be like this! If you put on the patch, because the amount of tin is certain, you will have less after separating the tin!

Devices are subject to moisture, such as tantalum capacitors

This phenomenon is called poor tin eating.

Several reasons: * The furnace temperature is not enough.

The PCB incoming solder joints are thin and the tin will be poorly eaten.

The furnace time is too fast and needs to be adjusted.

The PCB incoming solder joints are unclean (oxidized), resulting in poor tin eating.

The PCB needs to be pre-baked and heated before passing through the furnace, is it done?

If the surface treatment is anti-oxidation board, it is caused by poor incoming material treatment. The board factory has heavy antioxidant treatment.

I said I really don't know that there are other 3 items, he said that your current analysis problem is from the production analysis, not from the quality analysis, if you analyze from the quality analysis, everything is solved.

I was really depressed after the interview, but I learned a lot from it, and I knew my shortcomings, so I should learn from my seniors. . .

Personally, I think that the old is always a master of craftsmanship, equipment, and quality, and over the years, it is the only thing I admire.

The landlord good flux tin strip DXT-68A suggests that you measure the tin temperature to see if the tin is pure enough.

1. Confirm whether it is lead-free solder paste used, and it is normal for lead-free solder joints to be darker than leaded solder joints.

2. Confirm whether it is cold welding.

3. Whether the reflow oven has nitrogen turned on?

You see if you have nitrogen on.

Has the solder paste been replaced.