Quality Analysis of Wave soldering

- Mar 29, 2018 -

Wave soldering machines


Residual more

The FLUX high solid content, volatile too much.

The welding without preheating or preheating temperature is too low (dip, short time).

Our approach is too fast (FLUX not fully volatile).

The furnace temperature is not enough.

Low too many impurities or tin, tin.

The plus anti oxidant or anti oxidation caused by oil.

But too much flux coating.

Too much socket or open the PCB element, without preheating.

The element and foot plate hole (Kong Taida) the flux increased disproportionately.

And PCB itself is pre coated with rosin.

In the soldering process, the wettability of FLUX is too strong.

12.PCB process, a little hole, caused by the volatilization of FLUX is not smooth.

And when PCB hand dipped into the tin liquid wrong angle.

During the use of 14.FLUX, the diluent was not added for a long time.

Catch fire

1. the flux of the flux is too low and the flame retardant is not added.


2. no wind knife, resulting in excessive flux of flux, drop to the heating pipe when preheating.

The angle of the 3. blade is not right (the flux is not evenly coated on the PCB).

The PCB strip too much glue ignited.

There are too many flux on 5.PCB, drop down to the heating pipe.

The 6. approach is too fast (FLUX not fully volatile, FLUX drop) or too slow (caused by surface temperature

7. the preheating temperature is too high.

8. process problem (PCB plate is not good, heat pipe and PCB distance is too close).


(green components, black spot)


The copper and FLUX chemical reaction, the formation of green copper compounds.

The tin and FLUX chemical reaction, the formation of black lead tin compounds.

3 is not fully preheated (preheating temperature is low, equal speed) caused by FLUX residue,

4. the phenomenon of water absorption in the residue, (the conductivity of water soluble matter is not up to standard)

5. use of the need to clean the FLUX, after the end of the weld is not cleaned or not cleaned in time.

The activity of 6.FLUX is too strong.

7. the electronic components reacted with the active substance in FLUX.

Electric leakage

(poor insulation)

The FLUX on board into ions or FLUX residues; residual water, water conductivity.

PCB design is unreasonable, the wiring is too close and so on.

The quality of PCB solder mask is not good, easy conductive.

Leakage welding

The activity of FLUX is not enough.

The wettability of FLUX not enough.

FLUX coating amount is too small.

The FLUX coating is not uniform.

The PCB regional coating is not on the FLUX.

The regional PCB with no tin.

But part of the pad or the welding foot of serious oxidation.

The PCB layout is not reasonable ($parts distribution unreasonable).

The board is not the wrong direction, tin virtual preheating.

Not as tin or copper content exceed the standard; impurities caused by melting point of tin liquid [exceed the standard (liquidus)].

The foam pipe blockage, foam is not uniform, resulting in FLUX in the PCB coating is not uniform.

In the air knife set unreasonable (FLUX not blowing uniform).

And out of tune with good speed and preheating.

Third hand dipped tin improper operation.

Can the chain angle is not reasonable.

The crest is uneven.

Too bright or not bright

The FLUX problem: A. By changing the additive change (FLUX selection problem);

B. FLUX micro corrosion.

The tin is not good (such as: tin content is too low).

short circuit

The tin liquid caused by a short circuit:

A, joint welding but not detected.

B and tin solution do not reach the normal working temperature, and there is a "tin wire" bridge between the solder joints.

C, a small tin bridge between solder joints.

D, there is a continuous welding or bridge.

2, FLUX problems:

The activity of A and FLUX is low and the wettability is poor, resulting in tin between solder joints.

The impedance of B and FLUX is not enough, which causes the solder joint to be short.

3, PCB problem: such as: PCB itself resistance welding film fall off cause short circuit

Yantai Dalian, taste great

The FLUX itself is the problem

A, resin: if the flue gas is larger with the common resin

B, solvent: the smell or irritating odor of the solvent used in FLUX may be larger

C, activator: smog, and irritating smell

The exhaust system is not perfect, splash, tin:

1, flux

The water content in A and FLUX is larger (or exceeding the standard)

There is a high boiling point in B and FLUX (not fully volatilized after preheating)

2, process

A, low preheating temperature (FLUX solvent is not completely volatilized)

B, board speed did not reach the preheating effect

C, the chain angle is not good, the tin liquid between PCB and bubble, bubble burst after ball

The amount of D and FLUX coating is too large (no wind knife or bad wind knife)

E, improper operation of tin in hand soaking

F, wet working environment


3.The problem of PCB board

A.PCB is wet, not fully preheated, or produced by water

B. PCB runs gas hole design is unreasonable, resulting in PCB and tin liquid air pocket

C. PCB design is not reasonable, too dense foot parts caused by air pocket

D.PCB perforation


3. Problems of PCB board.

A, the board is wet, not fully preheated, or is produced water.

B. The hole design of PCB running gas is unreasonable, resulting in the gas between PCB and tin.

C, PCB design is not reasonable, the parts are too densely packed to make the gas.

D, PCB perforated hole.

Incomplete solder

The wettability of the agent FLUX is poor.

The activity of FLUX is weak.

The temperature is low and the temperature is too small.

It is used in double wave peak process, and the effective points in FLUX are completely volatilised once.

The preheating temperature is too high, so that activating agent can activate the activity in advance, and the activity is not active when the tin wave is treated, or the activity is very weak.

The speed of the moving plate is too slow, so the preheating temperature is too high."

Not uniform FLUX coating.

In the welding disk, the components of the components are badly oxidized, resulting in poor tin consumption.

FLUX coated too little; Failure to fully infiltrate PCB pads and components.

10. PCB design is unreasonable; The arrangement of components on PCB is unreasonable and affects the upper tin of some components.

FLUX is not foaming well.

1. The selection of FLUX is not correct.

2. The foaming tube hole is too large (generally speaking, the foaming pipe hole of FLUX is smaller, and the foaming tube hole of resin FLUX is larger)

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

4. Air pump pressure is too low.

5. The foaming pipe has the condition of leaking gas or plugging the pores, resulting in uneven foaming.

6. Excessive amount of diluent.

Too much foam

1. The pressure is too high

2. The foaming area is too small.

3. Excessive amount of FLUX in the welding groove.

4. Not adding diluent in time, resulting in excessive FLUX concentration.

FLUX change color

(some of the non-transparent FLUX added a few light-sensitive additives, such additions.

The additive will change color after light, but it will not affect the welding effect and performance of FLUX.


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

A. the cleaning is not clean.

B. Poor quality resistance welding film,

C, PCB sheet and resistance welding film do not match.

D. There is dirt in the borehole into the soldering film.

E. Hot air has been used too many times.

2. Some additives in FLUX can destroy the welding film.

3. Tin liquid temperature or preheating temperature is too high.

4. Excessive welding time.

5. PCB stays on the surface of tin liquid for too long when the hand is immersed in tin.

Electrical signal change

1. The insulation resistance of FLUX is low and the insulation is not good.

2. The residual is not uniform, the insulation resistance is not evenly distributed, and it can form a capacitor or resistor on the circuit.

3. The water extraction rate of FLUX is not qualified.

4. The above problems may not occur during cleaning process (or can be solved by cleaning)

If you have any questions about wave soldering machines,please let us know.