Sherry, I visited your user's group web page, WOW, there's a whole lot of info there. I will be digesting it for a while. Thanks for the heads up. Anne Ledger EMDS, Inc. > -----Original Message----- > From: Sherry Goodell [SMTP:[log in to unmask]] > Sent: Thursday, July 22, 1999 12:40 AM > To: [log in to unmask] > Subject: Re: [TN] HASL co-planarity > > Don, > This is my first time replying to a TN question, but here it goes. > > First, there is no industry standard that I am aware of on HAL > thickness. > The 80-800 microinches you refer to is a common specification called > out. I > have been processing PWBs to this specification for 14 years and have > never > had a reject for solderability. > > Having said that, if the panels are solderable and acceptable at that > thickness will be dependent on the HAL process that they were run on. > Not > all HAL is equal. A HAL Specification Guideline is downloadable at > http://www.tet-halco.com/main.htm. > > Given that HAL is a geometrically dependent process, the geometry of a > feature will affect the thickness results. Large features tend to be > thinner > than small features on the same side of the panel. This is due to > surface > tensions of the copper and solder and the distance of the solder to > wet-back > on a given feature. Smaller features should be more uniform than large > features. With horizontal HAL, when processed at a 45° angle, QFP > sites will > typically be very consistent from pad to pad. Typical 25 mil pitch QFP > sites > have a mean around 300 microinches with a standard deviation around 50 > microinches. The larger the pads, the thinner the solder deposit will > become. You may also wish to visit the site of a new group for more > information and studies on HAL Capability. > http://members.xoom.com/sgoodell/HUG/ > > For a solder thickness of 80 microinches (2.0 microns) with 6 - 12 > microinches (.0152 - 0.30 microns) of IMC, solderability should remain > excellent during storage. It is possible to have as much as 100 > microinches > (2.5 microns) of IMC, from some HAL processes and solderability or > shelf > life problems are emanate. It is true that for a solder thickness of > 80 > microinches, without knowing the type of HAL process used, could be a > problem. Intermetallic compounds (IMC) thickness can be minimized from > HAL. > Typical tin/copper IMC thickness is 6 to 12 microinches (.152 micron > to .30 > micron) average on a Unicote® horizontal leveler. Typical vertical hot > air > leveling processes can exceed 100 microinches of IMC. (Ref. > IPC-TM-928) That > is why it is important to know what type of HAL process is being used. > I hope this helps. If I can be of further assistance please feel free > to > contact me off line for details of studies and related questions. > Sherry Goodell > Mgr. Applications Engineering > TET Halco, 8 Delta Drive, Londonderry, NH 03053 > phone: (603) 437-8653 > Fax: (603) 434-4156 > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]]On Behalf Of Don Karp > Sent: Wednesday, July 21, 1999 8:56 AM > To: [log in to unmask] > Subject: [TN] HASL co-planarity > > > Hello All, > > I've been asked a stumper (for me anyway). > > Is there a specification for the co-planarity (?) of HASL across the > board? > My customer is concerned that thickness variations (80 microinches on > one > land / 800 microinches on the other land - for the same component) are > causing tilting of his components. > > I know that there are minimum thickness requirements which address > solderability, but have not heard of the above. > > Don Karp > Trace Laboratories - Central > -----Original Message----- > From: TechNet [mailto:[log in to unmask]]On Behalf Of Don Karp > Sent: Wednesday, July 21, 1999 8:56 AM > To: [log in to unmask] > Subject: [TN] HASL co-planarity > > > Hello All, > > I've been asked a stumper (for me anyway). > > Is there a specification for the co-planarity (?) of HASL across the > board? > My customer is concerned that thickness variations (80 microinches on > one > land / 800 microinches on the other land - for the same component) are > causing tilting of his components. > > I know that there are minimum thickness requirements which address > solderability, but have not heard of the above. > > Don Karp > Trace Laboratories - Central > > ############################################################## > TechNet Mail List provided as a free service by IPC using LISTSERV > 1.8c > ############################################################## > To subscribe/unsubscribe, send a message to [log in to unmask] with > following text in > the body: > To subscribe: SUBSCRIBE TECHNET <your full name> > To unsubscribe: SIGNOFF TECHNET > ############################################################## > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information. > If you need assistance - contact Gayatri Sardeshpande at > [log in to unmask] or > 847-509-9700 ext.5365 > ############################################################## ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. 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