Solder bond inspection is a necessary routine adopted by the electronics industry to validate contacts between printed circuit boards and individual electronic components.  The type of equipment used to perform inspections on surface mount components has so far been limited to Static x-ray and bench mounted optical systems. Now Olympus has created SolView, a new portable tool that takes optical inspection into a new era.    

Olympus SolView is a hand held inspection probe that enables inspections of components with a stand-off height as low as 0.02mm (20 microns).  This new ’engineer’s eyepiece’ provides a quick and easy inspections at low cost. 

Image 1 illustrates a J-Lead device that has been misplaced on the board during the component picking and placement process.  The functionality of the board is impeded and rework soldering may be required.   

Image 2 displays a J-lead device with too much solder on its joint.  The joint can become rigid and increase the chance of cracks if too much stress is applied to the component.  This type of fault may be due to poor set up of the screen printing process.  Insufficient solder also leads to component failure as it leaves the component too fragile.

BGA Joint Failure
Ball grid array packages are difficult to inspect because the solder bumps are tightly packed underneath the component processor core.  This allows increased board density, thus creating a greater functionality PCB.  The inner rows of a BGA package can be difficult to inspect, even with large optical equipment.  SolView can see the inner rows of solder balls allowing quick decisions to be made about a components solder joint quality and validity. 

The types of faults that may occur in BGAs include:

Image 3 illustrates a BGA package where the solder balls are raised.  This may be due to delamination.

Image 3. Raised solder balls on a BGA device taken with SolView-90
and an Olympus Camedia
digital camera

Eradication of lead by use of lead-free solder is fast becoming a reality for the electronic and electrical industry.  Due to health and environmental concerns a new EU directive will be enforced which strictly outlines the use of lead-free solder in printed circuit boards. 

The RoHS directive restricts the use of certain hazardous substances in electrical and electronic equipment.  This directive applies to original equipment manufacturers, importers, distributors and resellers of electronic and electrical equipment (EEE) for member states of the EU.  It is important to remember that this also affects any country selling equipment into the EU.  The only exemption is equipment used to protect the member states, arms, munitions, and war material. 

Lead-free solder has a different appearance to that of normal lead solder joints.  The surface is more dull and less solder spread occurs.  Due to the changes in material properties the soldering process will need to be modified.  Lead-free solder does exist, however it requires higher temperature processing which can cause issues with other lower melting point components on a PCB.  

Inspection of lead-free solder joints is paramount to the electrical and electronic industry.  To successfully implement the RoHS changes, manufacturers will need to understand the new lead-free solder formation and appearance.  SolView is a valuable tool that will help manufacturers gain a better understanding of lead-free solder bond formation in advance of the RoHS directive which becomes effective in July 2006.