I can think of several potential reasons - all solvable but at higher
|NotTaR of Television Sets : Why can't TV manufacturers learn to sold..
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- Mass of large component leads (like shields) does not get adequately
heated during manufacture leading to latent cold solder joints. While
they may look ok, the solder never actually 'wetted' the heavy pins
and therefore did not form a good mechanical or electrical bond.
- Thermal cycles and differential thermal coefficients of circuit boards,
traces, and solder. While it is not easy to do anything about the
material properties, using plated through-holes or a similar mechanical
via would greatly increase the surface area of the joint and prevent
the formation of cracks.
- Vibration. This is also directly related to the single sided circuit
boards without plated through-holes to strengthen the joints.
- Lack of adquate mechanical support (single sided circuit boards without
plated through-holes (vias).
I believe that the single most significantimprovement would come about
by using plated trhough-holes but this would add to the cost and apparently
the consumer is not willing to pay more for better quality and reliability!
Some designs have used rivlets - mechanical vias instead of plated ones.
While this is good in principle, the execution has often been flawed where
cold solder joints resulted between the rivlets and the circuit board traces
due to lack of adequate process control.
The Sony and RCA/GE tuner shield problem is interesting because this
could have been solved years ago at essentially no additional cost as
other manufacturers - and their own repair procedures - have proven.
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