Today’s Printed Circuit Boards (PCBs)
have evolved from 100% through-hole, 100-mil
technology
to a mixture of through-hole and surface mount
processes involving thousands of components and
precision to 1-mil tolerances (5-mil spacings).
Double-sided boards have evolved into multi-layer
boards where 5 and 6 layers are now very common
- as many as 14 layers have been used.
As the complexity of the PCB manufacturing process has increased, the possibility of process defects has also increased. A PCB has many potential causes of failure:
Metal traces not to specification
Broken buried metal lines
Vias
Delaminations of the board
Component misalignment
Bad components
Cold-solder joints
These are traditional types of PCB defects that
must be addressed on a daily basis. To complicate
the situation further, it is now very common to
have Chip-on-Board (COB), the direct mounting and
wiring of an integrated circuit on the PCB. Flip
chips and Ball Grid Array packages may be on the
PCB as well.
These technologies, while providing
a very dense board layout, also pose new challenges
to the board manufacturer: tighter tolerances,
more fragile die, underfill, and solder contacts
that are not visible to the naked eye.
To address these concerns, IAL has assembled equipment to identify the specific problem and the root cause. This equipment and its capabilities are:
Radiography (X-ray imaging)
Highlights cracks and other physical defects in the vias, buried metals, wires and other materials. Good for examination of hidden solder joints (such as BGAs, flip chips, etc.)
Acoustic Microscopy
Reveals cracks, delaminations, and voids in plastics and other materials. Complements radiography. Can image underfill voids and hidden solder joints.
X-ray Fluorescence
Measures the thickness and composition of films such as solder, copper, nickel, gold etc. used in the manufacturing of PC-boards. Helps maintain process control.
Surface Analysis
From contaminants on the board to dust found in the system, surface analysis techniques can be useful in identifying the source of the problem.
