PCB board parts fall seems to be a lot of process and quality control engineers dreams, but everyone encountered the problems are not the same, given that many people encounter such problems most do not know where to start analysis , So here to share some of the methods and steps for your reference.

If the general PCB board parts fall, most of the problems with the welding quality can not be separated, and its final answer is nothing more than one of the following, or a mixture of two or more of the results:

Board surface treatment problems.

Parts of the welding foot surface problems.

Poor oxidation of the board or parts due to poor storage conditions.

Reflow (Reflow) temperature process problems.

Welding strength can not withstand the actual use of external forces.

PCB board parts falling bad analysis of several steps:

The following Shanghai SMD chip manufacturers for the road to fall parts to analyze the steps to state, because it is hard to take some actions in steps, but some steps seem to be related to other steps,

The first step, information acquisition

This point is very important, if the source is wrong, no matter how brilliant behind are in vain.

Confirm the problem responder with a description of the symptom first and try to know the following information first:

What happened? Please try to describe the bad phenomenon clearly. Under what circumstances the parts fall? Has the product dropped? Under what circumstances (gas station, outdoor, indoor, air-conditioning)? Is there any special test (high and low temperature)?

The problem occurs in the client? Or production process? Is the problem occurring or discovered at that step of the process?

When did the problem happen? Is found in the production process? Or finished product testing was found? Bad products are not concentrated in the same Date-code?

What is the surface treatment of the board? ENIG? OSP? HASL? ENIG will have a black nickel problem, HASL will have a second-side over-eating tin problem, and the OSP will have an out-of-date tin problem.

The thickness of the board? 0.8mm? 1.0mm? 1.2mm? 1.6mm? The thinner the board, the greater the chances of warping and bending, and the more the problem of tin cracks may be.

Parts of the surface treatment of the foot Why? Matte Tin? Gold-plated?

Paste the main ingredient? SAC305 (tin silver copper)? SCN (tin copper nickel)? Different solder paste melting point will be different.

If you can call out the current reflow measurement curve is good.