Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Ken Fong

#9061

Rephrase : mixed technology criteria. | 9 October, 1999

Hi,

We are using mixed technology in our PCBA. Would like to know whether there is any criteria governing/guiding the use of mixed technology in such aspects as: 1. Some SMDs cannot be used in some kind of PCB materials such as FR1? 2. Some SMDs are not suitable for some soldering process such as ceramic capacitors not suitable for wavesoldering? 3. Is it advantageous to group SMDs into a single daughter board which is inserted onto the top side of the main board rather than putting all SMDs on the bottom side of the main board?

Any inputs regarding these or those related to mixed technology are highly appreciated.

Regards, KenF, Oct 7,99

Hi, netters, No response is received for my last message. I'd like to rephrase my question in more specific way, hope to get some replies :

Are there any international standards or practice on the following :

1. Limitations (size, shape, type or orientation on board) of SMDs to be used on FR1, CEM1, CEM3, FR4, copper based substrate, and ceramic substrate?

2. Limitations of SMDs to be used for such soldering processes as wavesoldering and reflow on the above types of circuit boards?

Any response will be highly appreciated.

Regards, KenF, Oct 9,99

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#9062

Re: Rephrase : mixed technology criteria. | 11 October, 1999

Ken: Since Earl is no longer here, I guess I'll bite on this. Your questions are very broad and difficult to answer specifically. So, I'll give you broad and non-specific answers.

| Hi, | | We are using mixed technology in our PCBA. Would like to know whether there is any criteria governing/guiding the use of mixed technology in such aspects as: | 1. Some SMDs cannot be used in some kind of PCB materials such as FR1?

Not that I'm aware of.

| 2. Some SMDs are not suitable for some soldering process such as ceramic capacitors not suitable for wavesoldering?

Yes, large value capacitors should not be wave soldered. Melf packages should not be wave soldered.

| 3. Is it advantageous to group SMDs into a single daughter board which is inserted onto the top side of the main board rather than putting all SMDs on the bottom side of the main board?

Tough to say. It would depend on the economics of assembling the specific board. | | Any inputs regarding these or those related to mixed technology are highly appreciated. | | Regards, | KenF, Oct 7,99 | | | Hi, netters, | No response is received for my last message. I'd like to rephrase my question in more specific way, hope to get some replies : | | Are there any international standards or practice on the following : | | 1. Limitations (size, shape, type or orientation on board) of SMDs to be used on FR1, CEM1, CEM3, FR4, copper based substrate, and ceramic substrate?

First, most trade developed specifications do not direct themselves towards that type of limitation. Second, I don't think so. Third, you can make the board as big, etc. as you want (can process). Two things:

1 Some classes of substrates are better suited to types of service than others, but that is more of a guideline than an out-right prohibition. 2 Some process machinery is limited in the size and shape board that it is able to process. | | 2. Limitations of SMDs to be used for such soldering processes as wavesoldering and reflow on the above types of circuit boards?

Different components can bear different process environments. For instance some, but not all through hole components can not be reflow soldered. Not all SMT devices can be wave soldered. | | Any response will be highly appreciated. | | Regards, | KenF, Oct 9,99 | Continuing, it sounds like you should take a design for manufacturing course at the next NEPCON West.

My2�

Dave F

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