Embedded PCB Components Issues
Small size modern electronic circuit board has a niche market share. To make smaller PCB, embedded component is an efficient solution. So far, embedded PCB components have played a vital role in the success of modern consumer electronics, military and satellite technology.
Embedding components within PCB substrate in concentrate the components space is generally referred to as embedded PCB components. Integrating the passive components under the main IC with say BGA package can make intense reduction in size, eliminate parasitic effect, use shortest possible trace to avoid interference in signal path on high frequency system, etc.
However, the design defects possibility also increase a little bit. Since the embedded PCB is designed in micrometer scale, maintaining precision is complex. The major issues existing while manufacturing embedded PCB boards are defective solder joints, inter component shorting, lack of thermal conductivity, substrate cracking and tomb stoning, as well as BGA intermittent connections.
Interconnecting components within the PCB substrate raises a huge challenge. Since the solder thickness is in few micrometers, the possibility of solder joint cracking is higher. Inadequate solder deposition, mechanical stress and tomb stoning are few major reasons causing solder joint breaks.
To prevent the joints from cracking, few precautionary steps must be taken.
Apply adequate solder paste-- Applying enough solder paste before the assembling results in uniform surface of solder with no leftover surface. This may also cause higher resistive path.
Avoid tomb stoning-- Tomb stoning occurs when the component deflects from its original geometry and either flips or offsets its appropriate position. To avoid this effect solder’s surface tension must be reduced. Identical quantity of solder pasted on available solder pads also solves this problem to a greater extent.
Effective heating method-- Heating the solder to bond the component to the trace is a crucial part. Lower temperature causes partial melting and bonding ability is degraded. On other hand if the temperature is too hot it may affect the components environment and causing it to bond in a irregular pattern. So ideal soldering temperature must be maintained.