Welding bad reasons and countermeasure-深圳市三智星科技有限公司

Bad solder solder
The phenomenon of some lines did not touch the surface of tin, due to:
1. The surface with oil, impurities and so on, can be solvent cleaned.
2. Substrates during the manufacture of abrasive particles left on the line the surface of printed circuit boards This is the issue of the manufacturer.
3. Silicone release agents and lubricants generally contain such oils, not easy to be completely cleaned. Therefore, the manufacture of electronic components in the process, should try to avoid those chemicals containing silicone oil. Solder used in the furnace to prevent oxidation of the oil also should be noted that the oil is not such.
4. As a result of storage time, the environment or process properly, or parts of the substrate surface oxidation of tin and copper surface dull serious situation. Flux is usually used for this problem can not re-solder a tin results will help to eat.
5. Flux improper use of the conditions of adjustment, such as foam and the air pressure required height. It is also important to share one of the factors, because the surface flux lines distribution of the number affected by the weight. Check the proportion of label can also be ruled out because of the wrong paste, storage conditions of non-performing due to the misuse of such factors as the possibility of improper flux.
6. Solder enough time or temperature. The general operating temperature of the solder melting point than the high-temperature 55 ~ 80 ℃
7. Parts of the terminal is not suitable material. Check the parts, make terminal clean, well James Baptist.
8. Preheating temperature enough. Adjustable pre-heating temperature, so that the surface temperature side substrate part to comply with the requirements of the temperature about 90 ℃ ~ 110 ℃.
9. Solder composition of impurities are too many do not meet the requirements. Solder can be measured in the time of the impurities, if not exceeding the standard, then the replacement of solder eligible.
When solder stripping
Occur in tin-lead substrate, and to eat unhealthy situation is similar to tin; For welding in the road surface and the tin from the tin when the wave, and most have James on the solder in its then pulled back to tin furnace, so situation is more serious adverse solder re-solder one may not be able to improve. The reason is that substrate manufacturing facility in the former tin-lead transition surface not clean. At this point of the substrate can be returned to the adverse re-processing plant.
Or cold solder joint is not smooth
This case might be classified as a non-uniform solder joint, occurred in substrates from the tin wave is solidified, the parts affected by external forces and the formation of solder joints mobile.
Substrate after soldering to keep the transmission in a smooth action, such as the strengthening of the fixed parts, the direction of attention to parts such as foot line; In short, the substrate to be welded have adequate cooling and then move to avoid the occurrence of this issue. Solution for the next wave of a tin.
As for cold, tin temperature too high or too low may result in this case.
Solder solder joints have the effect of cracks
Causes for the substrate, through the hole and solder joints in the feet and other parts contraction coefficient of thermal expansion in terms of misconduct, it can be said is not actually the problem of solder, but it involves the design of circuits and components, materials and size of the co-ordination in the heat .
Also, substrate assembly of the collision products, a stack is also one of the main reasons. Therefore, the substrate assembly products are to be collisions, a stack, pile up. Also, the shear line cutter is a major killer legs, auto-response plug-ins or the use of shear pin or procurement in advance do not have to cut the size of the foot parts.
Tin excessive
Excessive flow of solder joints on the current does not help, but the strength of the solder joints are not affected, the reasons are:
1. Substrates with contact angle of solder properly, change the angle (10 ~ 70), will enable the dissolved tin drip line from the greater tension, and the solder joints to be thinner.
2. Solder solder temperature is too low or too short, so that dissolved tin abundance less than the surface lines have been completely drip condensation.
3. Preheating temperature enough so that flux does not fully play the role of the surface of clean lines.
4. To increase the proportion of flux will also help to prevent the occurrence of large spot; however, should also pay attention to proportion is too high, after the substrate solder flux residues more.
Tin solder tip when
Online Parts footsteps on the road-side formation, is another over the shape of the solder.
This again pointed to the elimination of solder. Sometimes with this case and do not eat bad food tin tin the same time, for the following reasons:
1. Substrates poor solderability of the contact line inferred from the edge and do not eat bad food tin tin to confirm. Under such circumstances, once again had solder does not solve the problem, because as mentioned earlier, line the surface conditions were not good, this approach will have no effect.
2. Substrates did not plug the big hole. Solder into the hole, hole in the condensate when the number of solder due to too much down by gravity from an icicle.
3. In hand soldering, the tip temperature is not the main reason, or, even when the temperature enough, but the head of the soldering iron too, will also have an impact.
4. Metal impurity content was high, requiring the replacement of pure tin or solder.
沾附solder on the base plate
1. If it is not compatible formula and flux of chemicals left in the substrate, will result in the case. In the solder, these materials become soft due to high temperature tacky, and some live solder dip. Use strong solvents such as ketones, such as the type of substrate cleaning chemicals, will help to improve the situation. Occur if the solder is still attached to the substrate, the substrate may be in the baking process when handled properly.
1. Substrate manufacturing facility in the drying process laminates mishandling. Substrate assembly in the Add box before to 80 ℃ ~ 100 ℃ bake 2 to 3 hours, or improvements in this regard.
2. Solder and oxide impurities in contact with the substrate will also be caused by this phenomenon, this is a maintenance problem.
White residue
Solder or cleaning after the substrate is sometimes found with white residue, although the value does not affect the surface resistance, but the appearance of the factors is not acceptable. Causes as follows:
1. Substrate itself residues, absorbed flux, then solder and cleaning, on the formation of white residues. Maintain the substrate before the solder-free residue is very important.
2. Laminates of drying properly, occasionally found in a number of substrates, there is always a white residue, and approved the use of some substrates, the problems go away. Such reasons as a result of a white residue solvent generally can be cleaned.
3. Copper surface to prevent oxidation of the formula agents not compatible. Panel in the copper surface must have copper to prevent oxidation agent, such as factory coated substrate. Copper surface to prevent oxidation of the past are rosin as the main raw material, but there is the use of water-soluble solder flux process are. Therefore, after cleaning the assembly line on a white substrate rosin residues. If the cleaning process halogenated agent-plus-one will be able to resolve this issue. At present, there has been a water solvent agent to prevent oxidation of copper surface.
4. Substrates at the time of manufacture of the controlled process, so that substrate deterioration.
5. Use of the old flux, absorbing moisture in air, and in the soldering process of the water to form a white residue.
6. Substrates in the use of rosin flux when soldering it to stay too long after the time for cleaning, which is not easy to clean, solder and cleaning as much as possible to shorten the delay between the time, this phenomenon will be an improvement.
7. Cleaning solvents substrate excessive moisture content, absorption of the solvent composition in the local accumulation of IPA to reduce the cleaning ability. Solution for the appropriate solvent to remove water, such as the use of home water separator or the material to absorb moisture separator in the middle.
Dark traces of residue and erosion
Line in the substrate and solder joint surface, double-plate may be found up and down both sides of this situation, usually due to the use of flux and removal of misconduct.
1. The use of rosin flux, the solder did not wash in a short period of time. Delay too long before cleaning, resulting in traces of residual substrate.
2. Acid flux caused by the remaining spot will be dark and traces of corrosion. Solution in the solder immediately after cleansing, or join the neutralizer in the cleaning process.
3. Because of high temperature solder flux due to the charred remnants of a solution for the flux detected by the proposed factory solder temperature. Higher temperature to allow the use of the flux may dispense with the occurrence of such circumstances.
4. Solder impurity content does not meet the requirements, requiring the replacement of pure tin or solder.
Pinhole and stomatal
Appearance, the pinhole and the different pore diameter in pinhole smaller, are available at the surface, can be seen at the bottom. Pinholes and pores represent bubbles in the solder joints, but still show extended to the surface, the majority have occurred in the substrate at the bottom, when the bottom of the spread of the bubble completely burst open before the condensation, that is, the formation of the pinholes or pores. Formed for the following reasons:
1. In the line of substrates or parts of organic pollutants Zhanhua feet. Contaminated materials such plug-ins from the automatic machines, machine parts and adverse factors such as storage. Common solvent used to remove such pollutants easily, but in cases of silicone oil and similar products containing more difficult. If the problem is caused because the silicone oil, changes must be considered a source of lubricant or release agent.
2. Substrates containing electroplating solution, and similar materials produced by the water vapor, if the use of low-cost substrate materials, there may be such a water vapor inhalation, when the solder to generate sufficient heat, the solution resulting in stomatal gasification. Substrate assembly before baking in the oven, you can improve this problem.
3. Substrates packing too much or improper storage, the surrounding environment to absorb water vapor, it first before baking assembly.
4. Flux tank containing water flux to be regularly replaced.
5. Foam and air knife using compressed air contains too much water, the need to install water filters and regularly exhaust.
6. Preheating temperature is too low, can not evaporate water or solvent, substrate once tin furnace, instant contact with the heat, and have burst, so the need to increase the preheat temperature.
7. Tin temperature is too high, in the event of water or solvent, immediately burst, it will take to reduce the tin furnace temperature.
After the solder caused by short circuit
1. Pad designed properly, can be replaced by a circular oval-shaped pad to increase with the distance between points.
2. Parts direction are poorly designed, such as SOIC feet parallel with the tin wave, it will be a short circuit, the direction of modification parts to make it compatible with tin-wave vertical.
3. Automatic plug-ins caused by bending the foot, due to the provisions of IPC foot length of line in the following 2mm (ignorance of the way risk) and too much worry about the angle when the foot bends parts will be out, so easy to be caused by short circuit, solder joints need to leave the line more than 2mm.
4. Substrates hole too big, tin from penetrating to the hole on the side of the substrate caused by short circuit, it is required to narrow the aperture does not affect the degree of interpolation parts installed.
5. Automatically when plug-ins, the remaining parts of the legs too long, to be limited to the following 2mm.
6. Tin furnace temperature is too low, tin can drop back quickly, the need to increase the furnace temperature of tin.
7. Conveyor belt speed is too slow, tin can not drop back fast, faster conveyor speed to be adjusted.
8. Board poor solderability. Clean surface of the plate.
9. Substrates overflow of glass materials. In the welding surface before checking whether there are glass panels to highlight objects.
10. Solder Mask Failure. Solder Mask check the appropriate type and use.
11. Board surface contamination, surface cleaning of the plate.
Solder a dark and granular point of contact
1. More were due to pollution and melting solder in tin oxide is mixed with too much structure too brittle solder joint formation. Do not need to pay attention to the use of components containing low tin solder confusion caused by the dark.
2. Solder composition itself changes, excessive impurity content, plus the need