Bad analysis of wave soldering (3)

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Bad analysis of wave soldering (3)

Incomplete solder joints

1. Poor wettability of flux

2. Weak activity of flux

3. The temperature of wetting or activation is low and the flooding is too small

4. Double wave peak process is used, and the effective components in flux are completely volatilized in one tin pass

5. If the preheating temperature is too high, the activator will activate the activity in advance. When the tin wave passes, the activator has no activity, or the activity is very weak;

⒍⒍⒍⒍⒍ the plate moving speed is too slow, so that the preheating temperature is too high

⒎ uneven coating of flux.

8. Serious oxidation of pad and component foot, resulting in poor tin eating

⒐ too little flux coating; PCB pad and component pin are not fully wetted

10. The PCB design is unreasonable; the layout of components on the PCB is unreasonable, which affects the tin loading of some components

Bad Flox foaming

1. Wrong choice of Flox

2. The foam pipe hole is too large (generally speaking, the foam pipe hole of the wash free Flox is small, and the foam pipe hole of the resin Flox is large)

3. The foaming area of the foaming tank is too large

4. Air pump pressure is too low

5. The foaming pipe has the condition that the pipe hole leaks or blocks the air hole, resulting in uneven foaming

6. Too much diluent added

Too much foaming

1. Too high air pressure

2. The foaming area is too small

3. Too many flux are added to the fluxes

4. Diluent was not added in time, resulting in high concentration of Flox

FLUX discoloration

(some non transparent flux are added with some photosensitive additives, such as

The additive will change color after encountering light, but will not affect the welding effect and performance of flux)

Shedding or blistering

1. More than 80% of the reasons are problems in PCB manufacturing process

A. the cleaning is not clean

B. poor solder mask

C. mismatch between PCB and solder mask

D. there is dirt in the drilling hole entering the solder mask

E. too many times of tin passing during hot air leveling

2. Some additives in flux can destroy the solder mask

3. Too high bath temperature or preheating temperature

4. Too many times of welding

5. During the hand tin dipping operation, the PCB stays on the surface of the tin solution for a long time

Electrical signal change

1. Low insulation resistance and poor insulation of flux

2. Uneven residual and uneven distribution of insulation resistance, which can form capacitance or resistance on the circuit.

3. The water extraction rate of Flox is unqualified

4. The above problems may not occur when they are used in the cleaning process (or can be solved by cleaning)