PCB design in the production of the problem and solution
Substrate in the PCB design process may have the following problems
one. Solder a variety of issues
Signs of the phenomenon: cold solder joints or solder bursting holes.
Inspection methods: Pre-dipped and dip-welded after holes on the regular analysis, in order to find where copper stress, in addition, the implementation of feedstock testing of raw materials.
possible reason:
1. Blast holes or cold welds are seen after the soldering operation. In many cases, the copper plating is poor and then swells during the soldering operation, creating voids or holes in the metalized hole walls. If this is produced during the wet-processing process, absorb the volatiles
The material is covered up by the coating and then driven out by the heat of dip welds, which creates spouts or holes.
Solution:
1. Try to eliminate copper stress. The expansion of laminates in the z-axis or in the thickness direction is usually material dependent. It can rupture the metallized hole. Work with laminate manufacturers to get advice on materials with less z-axis expansion.
Two adhesive strength PCB design system
Symptoms: During the dip-soldering process, the pads and wires are detached.
Inspection method: In the feed inspection, fully tested, and carefully control all of the wet processing technology.
possible reason:
1. The detachment of the pads or wires during the process may be due to the plating solution, solvent attack, or the stress of the copper during the plating operation.
2. Punching, drilling, or perforation can cause the pad to partially disengage, which will become apparent during hole metallization operations.
3. In wave soldering or manual soldering operation, the soldering pad or wire is usually due to improper soldering technology or the temperature is too high. Sometimes because of the original bonding laminate or thermal peel strength is not high, resulting in the pad or wire detachment.
4. Sometimes printed circuit board design and wiring will cause the pad or wire in the same place.
5. During the soldering operation, the absorbed heat of retention of the component will cause the pad to detach.
Solution: PCB design system
1. Give the laminate manufacturer a complete list of the solvents and solutions used, including the processing time and temperature for each step. Analyze the plating process copper stress and excessive thermal shock occurred.
2. Abide by the push of the mechanical processing methods. Regular analysis of metalized holes can control this problem.
3. Most of the pads or wires are disconnected due to the strict requirements of all the operators. Failure of the solder bath temperature test or prolonged residence time in the solder bath may also occur. In the manual soldering trimming operation, the pad is probably due to improper use of wattage
Ferrochromium, as well as the failure to carry out professional process training. Some laminate manufacturers are now using rigid laminates to create laminates with high levels of peel strength at elevated temperatures.
4. If printed circuit board design and wiring caused by the detachment occurred in the same place on each board; then this printed circuit board must be redesigned. Normally, this does happen where a thick copper foil or wire is at a right angle. This is sometimes the case with long wires; this is because of this
For the sake of different thermal expansion coefficient.
5 PCB Design Time. Remove heavy components from the entire board, if possible, or after dip soldering. A low-wattage soldering iron is typically used for careful soldering, which is less time-consuming for the substrate material to heat up compared to component dip soldering.
three. Over-size changes in PCB design system
Symptom of the phenomenon: After processing or soldering substrate size beyond tolerance or can not be aligned.
Inspection methods: in the process of full quality control.
possible reason:
1. Towards the texture of the paper-based material, the direction of texture is not noticed, and the forward expansion is about half the width. And after cooling the substrate can not be restored to its original size.
2. If the local stress in the laminate is not released, it may sometimes cause irregular dimensional changes during the processing.
Solution: PCB design system
1. Exhort all the production staff to cut the board often according to the same tectonic texture direction. If the size changes beyond the allowable range, consider using the substrate.
2. Contact the laminate manufacturer for advice on how to release the material before it is processed.