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compactflash memory process requirements

francis khoo

#19575

compactflash memory process requirements | 18 April, 2002

Hello Industry Friends, Can anyone provide me with a guideline to compactflash memory processing requirements please.

Regards, Francis Khoo.

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#19577

compactflash memory process requirements | 18 April, 2002

Nothing special. [Follow your paste supplier's recommendations for reflow.] SanDisk� NAND flash memory are sold as TSOP [thin small outline package] devices.

Here�s what the innards of a card looks like: http://www.mittoni.com/information/insidecf.html

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#19582

compactflash memory process requirements | 19 April, 2002

I used to build flash memory products for M-Systems. Up to 30,000 per week. Nothing special in the process for these boards. 1mm and 0.4mm thick std. FR4 PCBs are used. Double-Sided reflow. The 0.4mm thin boards require process carriers. Panelized 24up, 12up and 6up depending on the product. Components are QFP at 0.4mm and TSOP at 0.5mm pitch, 1608 (0603) was the smallest chip. The only comment I can make was we had some trouble was with the design. The designers tend to want to make the PCB as small as possible and in doing so shorten the length of the TSOP solder lands so they are less than 1.2mm long per IPC SM-782. Other than that, a great product to build!

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francis khoo

#19600

compactflash memory process requirements | 19 April, 2002

Hello Dave, Thanks for you input. The website suggested to look into is exactly what I was looking for. I am very happy. Apart from the SMT portion of the process, I was looking at the plastic assembly as well. Do you know if the plastics are welded together by means of ultrasonic?

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francis khoo

#19601

compactflash memory process requirements | 19 April, 2002

Hello Pete, Thank you very much for your detailed information. Personally, I like shorter solder lands as it would provide a localised solder joint instead of spreading the solder on "unused" location. You have been very helpful. Much appreicated. Thank You, Francis Khoo.

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#19614

compactflash memory process requirements | 21 April, 2002

Francis, The problem with shorter solder lands is you may have a problem getting good heal fillets. In the flash products I built the PCBA was inserted into a plastic shell and then we did an epoxy encapsulation using a Camalot machine. Toshiba, Samsung and AMD also make NAND Flash in TSOP packages. Pete

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francis khoo

#19616

compactflash memory process requirements | 21 April, 2002

Hello Pete, Very true about the heel fillet. Looks like the pad at pcb has to be designed such that the pad should extend at heel but short at toe. About the encapsulation. I can understand the requirements. Can you provide me with a more detail process flow in it please. My guess on your process is, Place pcba into half plastic housing. Dispense encapsulation. Cure encapsulation and assemble the other half of the plastic housing. What encapsulate do you use. What is the cure temp. and time. If my process flow is correct, how do you assemble the second half of the plastic housing. Are there any specifications to the completed assembly. Example, thickness, length width etc. Thanks, Francis Khoo.

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#19623

compactflash memory process requirements | 22 April, 2002

Francis, The potting encapsulation process was in the mfg. of flash-disk devices built on a DIP formfactor. Compact flash do not normally get potted. Ultrasonic welding or snap-togther is methods for closing the compact flash housing. The potting material I used for the flash-disks is a UL approved 2- part epoxy. Due to NDA I cannot reveal the supplier. The finished product must comply with the dimensional spec and tolerance for compact flash products. Pete

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francis khoo

#19633

compactflash memory process requirements | 22 April, 2002

Hello Pete, Thanks for your insight. I understand and appreciate the NDA situation. I now have a good understanding of the process requirements thanks to you and Dave. Take care and keep in touch.

Warm Regards, Francis Khoo.

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