by Jack Goho
Gideon Analytical Laboratories received one failed surface mount device (SMD) 200 ECSH quartz crystal oscillator and a good SMD 200 ECSH for comparison. A crystal oscillator uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency, such as a quartz crystal. This frequency is commonly used to keep track of time, to provide a stable and repeatable clock signal for digital ICs, and to stabilize frequencies. Oscillator circuits incorporating them became known as crystal oscillators, but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.
The capacitor was inspected for external damage. There was a slight dent on the package. The SMD quartz crystal was sealed in a hermetic can with leads extending through a glass fillet through a steel plate substrate. There was damage to the glass fillet or the weld connecting the top to the substrate. The amount of solder in the solder joint joining the crystal to the lead frame had to be controlled well; too much would inhibit the crystal and too little will produce inadequate bond or breakage. There was not enough solder and therefore it was inadequate in holding the crystal in place.
The solder joint between the lead frame and post had no connection. There was space between the end of the crystal and the lead frame; this gap indicates movement. The package was dented, had less than normal amounts of solder, and completely open (no connection) when decapsulated. Gideon Analytical Laboratories concluded that this SMD 200 ECSH oscillator received a blow that severed an already inadequate solder joint, and during the application what remained of the solder connection failed because it was too weak.
Gideon Analytical Laboratories has identified the causes of thousands of electronic component failures over the past several decades. Gideon Analytical Laboratories has the experience, resources, and expertise to provide a quick and accurate explanation of why failures occur.