Having alternate boards flipped in a symmetrical layout means that only one solder paste screen is required. Also, the same placement control files and machine setups may be used, since the assembly panel looks the same whichever side is up. In really high volume it's not so much an issue, since a separate SMT line will be used to screen and place the second side of the board anyway.
This technique needs to be used with some caution if the boards are thin (e.g. PCMCIA) and there are fine pitch components on only one side of the card. In this scenario, the assembler is likely to have a preference for running the close-tolerance parts first up, when the boards are pristine, flat and have high solderability (if the board has a sacrificial solderability preservative like OSP or white tin, the reflow heat of the first side will also affect the yet-to-be-placed side, so the solderability of the second side won't be quite as good as the first). In short, talk to your assembler for their guidelines. John Haddy > -----Original Message----- > From: Dennis Saputelli [mailto:[EMAIL PROTECTED]] > Sent: Thursday, 28 February 2002 12:16 PM > To: Protel EDA Forum > Subject: Re: [PEDA] Flipped on panel Paired Mechanical layers (ex > Inversion ...) > > > Ian Wilson wrote: > > real reasons why correct inversion would be useful, another would be to > > facilitate panelisation where alternate rows of boards are flipped - to > > minimise machine setup. Leaving this to a PCB maker can be a source of > > error. Doing it in Camtastic is my preferred option but some > companies I > > work for like to have the panel in Protel for whatever reason. > > i've seen those panels with some boards flipped and never understood, in > fact i still don't > can you pls explain what this offers? > > thanks > Dennis Saputelli > > -- > __________________________________________________________________ > _________ > www.integratedcontrolsinc.com Integrated Controls, Inc. > tel: 415-647-0480 2851 21st Street > fax: 415-647-3003 San Francisco, CA 94110 > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
