Submitted by Fred Lofts (not verified) on Fri, 2007-10-19 07:21.
It would appear that due to the encapsulation, very few of today’s components can be used. Any device that is too large, too thick, needs outside control like push buttons; potentiometers or switches. Also, transformers, large capacitors, power resistors, IGBc modules, and the list goes on and on...
In fact, the 'what you can use' list is so small that only mid-sized chips and resistors and chip capacitors, that’s about it. So, what do I do when I design normal boards that use transformers, or potentiometers or, small 0201 chips or, all the big, fat protruding parts that you can not encapsulate?
Occam says they need to laser down to the component pad... Well, the pad end of small 0402 and 0201 chip resistors and capacitors are too small to hit with a laser.
No one has talked about how to connect to the encapsulated block: we need wires, connectors and pin outs, how would you encapsulate a connector and not have black goo leak in? How do I connect wires and test pins and other items I have to find and attach to for testing? Sounds like an impossible dream.
Occam says its simpler but, because it’s a single-sided device, it would require individual HDI layers made in sequence. I layer one, then another, and another, and so on, and so on. The time frame is huge.
Imaging a 10 layer board would require 10 lamination cycles, 10 dry film and imaging cycles, 10 developing and plating cycles, 10 separate etching cycles, 10 strip and AOI cycles. Meanwhile, when a HDI is made on a core because they process two layers at once (front and back) the PCB shop needs one-half as many process cycles.
An Occam board would be twice as expensive as today’s HDI boards.
With most HDI we design today, we place components on both sides. With Occam, your limited to one side. So, my boards need to be twice as large and now four times as expensive -- that’s not progress. Occam clams to be lighter but how much does the extra epoxy encapsulant weigh?
Not a practical idea .
Fred Lofts
PCB Designer
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It would appear that due to
It would appear that due to the encapsulation, very few of today’s components can be used. Any device that is too large, too thick, needs outside control like push buttons; potentiometers or switches. Also, transformers, large capacitors, power resistors, IGBc modules, and the list goes on and on...
In fact, the 'what you can use' list is so small that only mid-sized chips and resistors and chip capacitors, that’s about it. So, what do I do when I design normal boards that use transformers, or potentiometers or, small 0201 chips or, all the big, fat protruding parts that you can not encapsulate?
Occam says they need to laser down to the component pad... Well, the pad end of small 0402 and 0201 chip resistors and capacitors are too small to hit with a laser.
No one has talked about how to connect to the encapsulated block: we need wires, connectors and pin outs, how would you encapsulate a connector and not have black goo leak in? How do I connect wires and test pins and other items I have to find and attach to for testing? Sounds like an impossible dream.
Occam says its simpler but, because it’s a single-sided device, it would require individual HDI layers made in sequence. I layer one, then another, and another, and so on, and so on. The time frame is huge.
Imaging a 10 layer board would require 10 lamination cycles, 10 dry film and imaging cycles, 10 developing and plating cycles, 10 separate etching cycles, 10 strip and AOI cycles. Meanwhile, when a HDI is made on a core because they process two layers at once (front and back) the PCB shop needs one-half as many process cycles.
An Occam board would be twice as expensive as today’s HDI boards.
With most HDI we design today, we place components on both sides. With Occam, your limited to one side. So, my boards need to be twice as large and now four times as expensive -- that’s not progress. Occam clams to be lighter but how much does the extra epoxy encapsulant weigh?
Not a practical idea .
Fred Lofts
PCB Designer