The SMT craft quality check

一、check contents
(1)The component has already had no lapse
(2)The component hasn't stuck wrong
(3)Have no short circuit
(4)Had no falsely holdering

The above kinds of ex- circumstances are easy to check for the clear reason, but falsely soldering the is more complicated.

二、The judgment of the falsely soldering
   1.Adopting the on-line test instrument appropriation equipments(be so called a needle bed) carries on an examination.
2, the eyes see(contain to use magnifier, microscope)  examination.When the eyes see to discover the soldering ordered soldering to once anticipate a little soldering gradually bad, or slodering ordering have already broken to sew in the center, or the soldering surface present a convex globosity, or soldering and SMD melt in person not and mutually etc., will ahem, the even if slight phenomenon will also result in the suffer from, should judge immediately whether is exist a batch falsely a soldering problem.Method of judging BE:See whether more PCB ascend same soldering of position order to all have a problem, such as just individual PCB problem, may be a soldering cream to is pared off and lead feet to transform etc. reason, if same positions all have a problem on a lot of PCBs, be very likely to be what component not like or soldering dish include problem to result in at this time.
三、the reason of the soldering and solve
1.The soldering dish design contain blemish.On the soldering dish shouldn't existence bore, the bore will make the soldering run off to result in the soldering anticipate shortage;The soldering dish is apart from, the area also needs standard to match, otherwise should correct a design as early as possible.
2.The  PCB plank has already oxidized phenomenon, namely the soldering dish deliver black not bright.If oxidized phenomenon appeared,you can clear the layer with the eraser, making its glow-in-the-dark re-appeared.If the PCB plank affects by damp and cold, you can dry it in the dry box.The PCB plank contain pollutions, such as oil stains and sweat stains.etc., you need to use water ether to be pure to clean at this time.
3.Once printed the PCB of soldering cream, the soldering cream was pared off, make the soldering cream of related soldering dish measure decrease, make the soldering anticipate shortage.Should make up deficiency in time.The method of repairing can use some gum machine or pick with the bamboo label few make up deficiency.
  4. SMDs(the form stick a dollar spare part) quality not good, overdue, oxidize, transform, result in falsely soldering .This is more see of reason.
1)The oxidizing component is black not bright.The melting point of oxide goes up, at this time plus a loose fragrant type to help a soldering with the electricity chrome iron of more than 300 degrees can weld, but use the SMT reflux of more than 200 degrees, the soldering pluses again usage causticity weaker don't need to clean a soldering cream hard melt.Past the SMD oxidized should not use to flow again a soldering stove to weld.Must see pure while buying a component whether have the circumstance for oxidizing, and buy back to want to use in time behind.The soldering cream managed together, oxidized can't use, either.
(2)Several PINS stick to pack a component, because  of thick pin, are easyly to transform under the function of outside dint. once transforming, the  affirmation will take place falsely soldering or lack the phenomenon of soldering , so you must  check hard to repair in time before stick and after soldering