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 ##############################################################