| Hello; | | I am looking for general info on backplane assemblies. Any info would be appreciated, but some of the questions that come to mind include: | | -What part types other than connectors do backplane cards have on them? SMT? Leaded? Quantity? Is this commonplace? | | -What is the board thickness/layers range? | | -What size ranges have people seen for backplane cards? | | -Any double sided backplane cards? | | -Are press fit connectors more prevalant than wave soldered connectors? | | What are the common processing issues associated with backplane assembly? | | Thanks!

Backplane assemblies vary widely with the application. We typically see large boards (some more than 40")with low mix and quantity. What we are seeing is jelly bean components and smaller actives usually not bigger than solic and PLCC20 devices. As you might expect these cards are usually .060 or thicker (Some much thicker.) We have been dealing with mostly surface mount connectors, some with guide posts. These connectorts seem to have really improved over the last few years. The big concern is handling. These boards are not rocket science but they pose a real challenge to run of the mill SMT equipment because they just can't handle the size and size associated problems. Printing,assembly and reflow all have their unique concerns. Most of the houses we have been dealing with partner with us. This seems to be the only way to handle the always unique applications.

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Wendy Casker

#12381

Re: Backplane Assembly Info Request | 8 March, 1999

Hello, We are a contract house which specializes in backplanes and box build. As the manufacturing engineer, i have seen backplanes from .060 to .250 thick, from 2X4 " to 18X24. I have seen up to 24 layers. We have seen everything on backplanes from double sided press fit, double sided fine pitch SMT,and hand soldering . Most of the devices are passives, mainly caps and ferrites for EMI purposes. Our larget backplane has 1000 SMT passives on it, as well as 45 SSOP48's, scattered on both sides.

We do use a production Quad QSV-1 to handle SMT, with the largest board we've done at 18.75 x24. (Bigger than Quad said we could do)

You need to carefully analyze your process, as it can include many things. Pressing after SMT poses many challenges for back up tooling, so you can press without breaking any of the SMT parts you just put down. Needless to say pick and place and reflow are fun when the boards hit monster size. We are finding that screen printers are our gate. Several of our boards are too large for our printer, so we use a jig to hold everything steady. Fortunately, these are low volume (and high revenue!) pieces. There are large frame screen printers out there, check out SMTechniques for theirs, as well as transition Automation.

If you are going press fit, then you'll need to look at both insertion and back up tooling.

I would be happy to talk to you about BKP's any time, just drop me an e-mail.

TTYL, Wendy

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