1. [hierarchical]
Layering is the long-standing problem of the PCB, ranked first in the FAQ. Its causes may be as follows:
(1) improper packaging or preservation, damp;
(2) to save a long time, more than the storage period, PCB board damp;
(3) the supplier material or workmanship;
(4) design selection and poor distribution of the copper surface.
      Moisture problem is more likely to occur, even if the election good packaging, there are constant temperature warehouse in the factory, but shipping and staging process is impossible to control. I had the "honor" visited a bonded warehouse, temperature and humidity management do not expect, the roof is still leaking, the box is to stay in the water directly. But moisture can still cope, vacuum conductive bags or aluminum foil bags are good protection against the intrusion of moisture, while its packaging requirements put humidity indicator cards. If you find before using excessive humidity card, on-line before baking can generally be resolved, baking conditions are usually 120 degrees, 4H.
      If you are a vendor material or workmanship problem occurs, the possibility that scrap is relatively big. Common Possible causes include: brown (black) of bad, PP or inner plate damp, inadequate PP glue, lamination abnormalities. To reduce the problems of this situation requires special attention PCB supplier for the corresponding process management and hierarchical reliability test. In reliability tests of thermal stress test, for example, a good factory standards are not stratified by more than 5 times in the sample stage and each cycle of mass production will be confirmed, and may be just an ordinary factory through standard 2 times, months to confirm once. The placement of the IR simulation test may also be more prevented the outflow of defective products is an excellent PCB plant essential.
     PCB design course design company will bring its own risk stratification. Such as sheet Tg choice, many times there is no requirement that PCB plant in order to save costs, certainly use an ordinary Tg materials, heat resistance will be relatively poor. In the lead-free into the mainstream of the times, or choose Tg safer or more at 145 ° C. Also open big and too dense copper surface area is buried vias PCB delamination problems, need to be avoided in the design

2. Adverse solder]
     One solder is relatively serious problem, especially in the bulk of the problem. The reason it may happen that the plate surface contamination, oxidation, black nickel, nickel thick abnormal, solder SCUM (shadow), long storage time, moisture, the solder PAD, thick (repair).
     Contamination and moisture problems are better solved other problems too much trouble, and there is no way to pass incoming inspection found that when plants need to focus on PCB manufacturing process and quality control plan. Such as black nickel, need to look at PCB plant is not of gold outgoing, for their analysis of the frequency of the golden thread of syrup adequacy concentration is stable, whether set up regular gold peel test and phosphorus content of the test to detect the internal solder test Are there any good execution. If you can do, that the possibility of batch problem is very small. While the solder PAD and repair bad, you need to understand PCB supplier for standard overhaul enacted, inspectors and maintenance personnel if a good job evaluation system, while clearly defined land-intensive areas can not be repaired (such as BGA and QFP) ʱ??

3. [plate bending Alice]
     Possible causes plate bending Alice are: supplier selection problems, abnormal production process, heavy poorly controlled, transported or stored improperly, broken hole design is not strong enough, the layers of copper and other differences too large. The last question on the need to design 2:00 in the early design review be avoided, but may require mounting IR PCB plant simulation test conditions to avoid too bad after the furnace plate bend. For some sheets may be required at the time of packaging upper and lower pressure plate after pulp packaging, to avoid subsequent deformation, while adding jig when the patch to prevent excessive bending device board.

4. [scratched, exposed copper]
     Scratches, exposed copper is the biggest test PCB factory defect management system and execution. This problem is not serious to say serious, but does bring quality worries. Many PCB companies will say, this question is difficult to improve. I have been pushing too many scratches improve PCB factory, I found that many times is not a bad change, but want to go to change, there is no incentive to change. Any serious effort to promote the project in PCB plant, DPPM has delivered a significant improvement. So the trick to solve this problem is: push, push.

5. [bad] Impedance
     PCB impedance is an important indicator related to the phone board RF performance, the general common problem is that PCB impedance difference between the relatively large batches. Now that the impedance of the test strip is typically done in large PCB board edge, not shipped with the board, so you can pay the supplier on the batch impedance strip and test reports for each shipment reference, also requested plate diameter and plate edge inside diameter of comparative data.

6. [BGA solder voids]
     BGA solder voids may cause bad master chip functions, but may not be found in the test, hidden at high risk. So now a lot of patches plant will be posted after the member had X-RAY inspection. Such bad might happen because the PCB hole residual liquid or impurities, high temperature vaporization, or a bad laser bore hole on BGA pads. So now a lot of HDI board requires filling hole plating or semi-filled hole making, to avoid this problem from occurring.

7. [solder blister / off]
     Such issues are usually PCB solder process control abnormal, or the choice resist ink is not suitable (cheap, non-gold type of ink, not suitable for the placement of flux), it may be a patch, heavy overheating. To prevent the batch problem, we need to develop PCB supplier reliability test requirements corresponding control is performed at different stages.

8. [bad] jack
     Adverse plug hole PCB factory mainly lack technical capacity or the result of simplifying the process, its performance for the plug hole is not full, the grommet has exposed copper or pseudo-exposed copper. It may result in insufficient amount of solder, the patch or assembly device short hole residual impurities and other issues. This issue can be found on visual inspection, it is possible to feed test can be under control, requiring PCB plant improvement.

9. Adverse size]
     The size of the possible causes of a lot of bad, PCB production process prone to expand and contract, the supplier adjusted the drilling program / Graphics ratio / Forming CNC program may result in placement prone to misalignment, structural problems with the bad. Because of such problems is difficult to check them out, can only rely on suppliers good process control, so they need special attention in vendor selection.

10. [A] Tiffany effect
     A Tiffany effect is learned in high school chemistry galvanic cell reaction occurs in the selectivity of the gold plate of OSP processes. Since the potential difference between gold and copper in the OSP process flow connected with Daikin surface copper pads will continue to lose electrons dissolve into divalent copper ions, resulting in the pad becomes smaller, the impact of the subsequent component placement and reliable sex.
     The problem, though infrequent, never appears in Plato, and that the bulk of the problem but once. Mobile PCB production experienced mill will be selected by computer software this section pad, designed to compensate in advance, and set special conditions and restrictions Heavy Heavy OSP times in the process, to avoid problems. So this problem can be confirmed at the time of the audit in advance MILL.
    The above problem is not the short / open included, because this is the most fundamental issue PCB, Which MILL are unavoidable, mainly to see who process yield is relatively high, error prevention is better, relatively strict repair standards, PPM control lower than the.