Hi Techies You might benefit from using the IPC-TM-650 2.4.35 and 2.4.43 thru 46 test methods to control your paste prior to use on the line. Although these are currently in review for lead-free, I have some info to share if it will help. Graham Naisbitt Co-Chair TM-650 Test Methods Sub-Committee On 2 Nov 2008, at 19:53, john queen wrote: > This is an interesting one can anyone share there DOE of paste > selection and printer setup > ----- Original Message ----- From: "John Goulet" > <[log in to unmask]> > To: <[log in to unmask]> > Sent: Sunday, November 02, 2008 7:01 PM > Subject: Re: [TN] Controlled RH% Versus Screenprinting Results > > > The viscosity of the solder paste also varies greatly with > temperature change > that is easier to control. I've had to resolve the same issue at other > companies and currently resolving it in this building and layout > again. > Here are some things to consider before spending $500K. > 1. Is the Receiving Dock and Incoming area totally sealed off from > the SMT > area. It is pretty hard to manage temperature and humidity control > with 10' > doors open many times a day. In one factory we put up a frame and > sheet > rock walls around the dock and another for the receiving area. > Problem gone. > 2. Are the air handlers equipped with programmable thermostates. If > they > aren't and they don't have the dehumidifier options in them then at > night they > will blow in cool damp air because it is cool enough the air- > conditioner will be > acting as a fan only. In the current factory we going to do this > before summer. > Hopefully we'll also separate our SMT area as stated in #1. > 3. Try some of the newly released solder pastes. Indium just came > out with > 6.3 WS tin/lead that is far better than the 6.2. Senju may not be > well known > in the USA but in an extensive DOE they were the best for all > finishes. Senju is > the #1 paste overseas. > 4. The paste storage and handling in the productin line to prevent > the flux > from separating is important. A low voume high mix shop may need to > buy > 5000 gram or less and not the 7000 gram tubes since you can't put > them back > in the refrigerator. Large beads of paste over 1/2" may be easier > for the > operator but in higher humidity and temperature the paste on the > stencil is > going to change for the worse. The paste spec is written for beads > up to 3/4" > but that is in ideal RH and temp situations. Small factories that > weren't > designed for this industry are prone to the same situation that you > have. One > large factory had a huge sock like air exhange units that blew in > whatever air > is outside. In the winter you can have small humidifiers added but > in the rainy > spring and humid summer you have to relay on using the best paste > and very > good handling controls. Keep the jar low on the rack or floor since > since with > air conditining the floor will be at a lower temperature > approximately 72F. The > temperature in the machine it may reach 78-80 if you didn't add the > small fan > for the summer months. In this way when the operator adds the paste > you'll > stay in the middle of the control range. > > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > 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 > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 > for additional information, or contact Keach Sasamori at [log in to unmask] > or 847-615-7100 ext.2815 > ----------------------------------------------------- > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > 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 > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 > for additional information, or contact Keach Sasamori at [log in to unmask] > or 847-615-7100 ext.2815 > ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------