Effect of flux on board residue

- Oct 16, 2018-

White residues found on the substrate after soldering or solvent cleaning, usually rosin residues, do not affect surface resistivity but are not accepted by the customer.Flux is usually the main cause of this problem. Sometimes another flux can be used to improve the situation.Residual impurities in the production process of the substrate can also produce white spots in long-term storage, which can be cleaned with flux or solvent.Incorrect CURING also can cause the day, is usually a batch separately, should be timely feedback base board and the supplier use flux or solvent wash.

If the flux used in the factory is not compatible with the oxide protective layer of substrate, it will happen to the new substrate supplier or change the flux label, the supplier should be asked to assist.The shorter the storage time, the better, as the solvents used in the preparation process of the substrate change the substrate material, especially the solution in the nickel plating process often causes this problem.The flux is used for a long time and is exposed to air to absorb water and gas degradation. It is recommended to update the flux (usually the foaming flux should be updated weekly, the soaking flux should be updated every two weeks and the spray flux should be updated monthly).Use rosin solder flux to clean the solder furnace after the waiting time is too nine, resulting in a day shift. Shorten the solder and cleaning time as much as possible.

The solvent moisture content of cleaning substrate is too high, which reduces the cleaning capacity and produces a day shift. The solvent should be renewed.DARK residue AND DARK etching trace RESIDUES AND ETCH MARKS:

Black residue usually occurs at the bottom or top of the solder joint. This problem is usually caused by improper use of flux or cleaning.

The rosin-type flux is not cleaned immediately after soldering, leaving a dark brown residue, and it can be cleaned as early as possible.Acid flux left on the solder spot causes black corrosion color and cannot be cleaned. This phenomenon is often found in hand welding.The organic solder will be burned at a higher temperature, resulting in black shift.

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Green usually is caused by corrosion, especially the electronic products but is not entirely true, because it is difficult to distinguish what is green rust or other chemical products, but generally found that green stuff should be warning, must immediately find out the reason, especially the green material will be more and more big, should pay attention to very much, usually available to improve the cleaning.

Corrosion problems usually occur on bare copper surfaces or copper-containing alloys. Non-rosin flux is used.

COPPER ABIETATES are the compounds of COPPER oxide and ABIETIC ACID (the main component of rosin), which are green but by no means corrosive and have high insulation, which do not affect quality but the customer will not agree to cleaning.

PRESULFATE residues, or similar residues in substrate production, produce green residues after soldering. The substrate manufacturer should be required to conduct cleanliness tests after the substrate cleaning to ensure the cleanliness of the substrate.

white corrosion .talking about white residue is refers to the substrate white residue, and the project talking parts foot and white on metal corrosion, especially lead composition more easily into such residues on the metal, mainly because of chloride ion is easy and lead form lead chloride, lead again with carbon dioxide to form carbonic acid corrosion (white).

When using rosin flux, as rosin does not dissolve in water, it will not cause the chlorine-containing active agent to be coated with corrosion. However, if the improper solvent is used, the rosin can only be cleaned without removing the chloride ions, which will accelerate the corrosion instead.

Glabellum pinholes AND BLOWHOLES

The difference between pinhole and stoma is that a small hole is found on the solder joint, and a big hole can be seen on the solder joint. Inside the pinhole is usually empty, and the pore is a big hole caused by the complete internal air ejection. The reason is that the solder solidifies before the gas is completely excluded.

Organic pollutants (pops) : the base board and parts feet caused pinhole or porosity, gas may be produced its pollution source may come from planting a machine or storage condition, the problem is simple as long as the solvent wash, but such as contaminant SILICONOIL because its not easy to be solvent cleaning, therefore, should be considered in the process of other substitutes.

Substrate moisture: such as using the base material of cheaper, or use a rough way of drilling, the penetration hole easy absorption of moisture, soldering process caused by high heat evaporates, the solution is two hours at 120 ℃ baking in the oven.

Brighteners in electroplating solution: when a large number of brighteners are used for electroplating, the brighteners often deposit with gold at the same time, which will be volatilized when exposed to high temperature.


Oxidation prevents oil from being poured into the tin tank through jet flow and contaminating the base plate. This problem should be solved by adding solder in the tin tank because the solder level is too low.

Solder gloomy:

This phenomenon can be divided into two types of gradual solder solder over a period of time (about half a year to a year).

The finished welding spot is dark.

Impurities in solder: the metal composition in solder must be tested regularly every three months.

Flux may also produce a certain degree of grey on the hot surface. RA and organic acid flux left on the solder for too long may also cause slight corrosion and appear dark. Cleaning immediately after welding should improve.

Some inorganic acids can cause any ZINC flux OXYCHLORIDE available 1% hydrochloric acid cleaning and washing.

In solder alloys, solder joints with low tin content (e.g., 40/60 solder) are also dark.
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Rough surface of welding spot:

The surface of the solder joint is a sandy protruding surface, but the overall shape of the solder joint does not change.

Crystallization of metal impurities: the metal composition in the solder must be tested periodically every three months

Tin residue: the tin residue is poured into the tin tank by PUMP, and the surface of the solder spot is sanded and protruded because there is tin residue in the solder tank. The solder liquid level in the tin tank should be too low.

Foreign substances, such as rough edges and insulating materials, are hidden in the feet of parts, which also produce rough surfaces

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