TECHNET Archives

November 2011

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Inge Hernefjord <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Inge Hernefjord <[log in to unmask]>
Date:
Mon, 14 Nov 2011 22:56:46 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (120 lines)
Rocky,
there are lots of 'it depends', as would say certain can opener.
- What kind of product, commercial, MIL, Space, toys etc? These dictate the
general  requirements
- decide low moisture permeability level
- decide mobile ions barrier
- decide level of repair ability
- decide level of encapsulant purity
- decide the dielectric constant to match the propagation delay requirements
- decide the vulnerability against alfa particles (some semis are)
- decide the thermal conductivity
- surface tension (vs encapsulant)
-decide warpage
-others may fill in...lots

To use Pertinax or CEM is maybe not an easy task for unexperienced
designers, but could be a good idea if you got money and time and lots of
go in you. I don't belong to the rigid who say No to every unusual
proposal. You have probably seen the 'computers' built on paper and which
can be rolled and put in a tube. So, why not make a try. Personally, i know
little about paper substrates.

So, it's not easy to give a precise advice not knowing the expected final
product.
I was engaged in COB twenty years ago, very amusing job. There is a lot of
litterature about COB, one very good book is this one:
Chip On Board edited by John H. Lau ISBN 0-442-014441-4  Van Nostrand
Reinhold NY

Good Luck

Inge



On 14 November 2011 14:25, Joyce Koo <[log in to unmask]> wrote:

> BT
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Rocky Wang
> Sent: Monday, November 14, 2011 3:22 AM
> To: [log in to unmask]
> Subject: [TN] PCB substrate material choose for COB product
>
> Hello Technetters;
>           If there anybody has the knowledge to choose the PCB substrate
> material (Paper board, CEM, FR-4) for COB product?   For sure FR4 will be
> the best. However, why in some case, Paper material work, and in some case,
>  go to CEM material. If there have some choose guideline, such as from the
> die bonding pad size, pad pitch, number of bonding wire, and the size of
> the bonding wire or other conditions?
>
> Best Regards
> Rocky
>
>
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 16.0
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to
> [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to
> [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> For additional information, or contact Keach Sasamori at [log in to unmask] 847-615-7100
> ext.2815
> -----------------------------------------------------
>
> ---------------------------------------------------------------------
> This transmission (including any attachments) may contain confidential
> information, privileged material (including material protected by the
> solicitor-client or other applicable privileges), or constitute non-public
> information. Any use of this information by anyone other than the intended
> recipient is prohibited. If you have received this transmission in error,
> please immediately reply to the sender and delete this information from
> your system. Use, dissemination, distribution, or reproduction of this
> transmission by unintended recipients is not authorized and may be unlawful.
>
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 16.0
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to
> [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to
> [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> For additional information, or contact Keach Sasamori at [log in to unmask] 847-615-7100
> ext.2815
> -----------------------------------------------------
>


______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 16.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2