DVD-71C IPC-A-610E Common Inspection Errors - IPC Training ...

DVD-71C TranscriptThe common misinterpretations that we’ll be covering in this video include: inspector‘sresponsibilities; identifying board sides; electrical clearance; wetting angles; vertical fill ofthrough hole solder; through hole part clearance; gull wing leads; bottom terminationcomponents; measling; and billboarding.Inspector’s ResponsibilitiesLet’s begin with inspector’s responsibilities. A serious mistake can occur when an inspectorevaluates an assembly with excellent solder joints -- and identifies them as Class 3 solder joints.The reality of this situation is that the customer determines the class of product your company isbuilding. The inspector only applies the acceptance criteria. A solder joint that barely meets theminimum acceptance requirements for an mp3 player would definitely be undesirable for a lifesupport system. As you know, electronic products are divided into three classes – depending onthe ultimate use; the life expectancy; and the operating environment of the electronic assembly.Let’s review these classes of products.Class 1 refers to general electronic products – which include consumer electronics such astelevisions, stereos and video games. Class 2 includes high-end computers, telephone controlsystems and other commercial equipment that falls into the category of dedicated serviceelectronic products. The Class 3 category is for high performance electronic products –equipment with high reliability applications such as military, aerospace and life- support systems.The customer specifies the class your company will be building to and the inspector has theresponsibility to determine the four levels of acceptance for the solder joint – based upon the classthe customer has chosen. These four levels are target, acceptable, process indicator and defect.The target solder joint is close to perfect – the most desirable condition – but not alwaysachievable. An acceptable solder joint is not necessarily perfect, but provides a satisfactorymechanical and electrical connection to operate properly. A process indicator identifies acharacteristic that does not negatively affect form, fit or function of a product. It is not a defect.The solder connection will work fine and be reliable. A process indicator tells you that there is anopportunity for improvement in the quality of your solder joints – and other elements of thecompleted assembly. The process indicator usually points to a difficulty in the process thatshould be remedied. The process can include machine adjustments, product design, defectivecomponents and training needed. Finally, a defect does affect form, fit or function and willrequire rework, repair or even scrapping the assembly.The problem with applying class 1 acceptance criteria to class 3 products is obvious. However,applying class 3 criteria to class 1 products make the class 1 products much more expensive tomanufacture. As you can imagine, it could be a time consuming and expensive mistake for aninspector to ask for rework of a solder joint that did not need to be reworked based on class ofproduct. And that mistake can also add unwanted heat to the circuit board causing internaldamage.2