---------------------- Forwarded by Ed Holton/Hella North America Inc. on 02/16/98 03:04 PM --------------------------- Ed Holton 02/16/98 12:52 PM To: [log in to unmask] cc: Subject: Re: [TN] To On or Not to On (Document link not converted) Wow, isn't workplace politics fun!?! I have to assume that the supervisor has experienced non-soldered boards from the wave solder system, otherwise, there would not be a concern about the sensor sensing the boards or not. Remember, if it works, they don't complain about it. HOWEVER: The sensor is there to activate the wave when the board is present for soldering. Without the sensor, the wave will run continually, and the amount of dross generated will be increased. The less dross generated in the pot, the less it has to be cleaned, etc. Everytime you clean your pot, you run the risk of changing a variable (pot height, wave height, solder level, etc. This is why the newer systems have controls on these features to they can be returned back to nominal conditions) SO: review the sensor operation, the sensor may need to be cleaned or adjusted. Why disable something on the machine because you do not think it works, FIX IT!!!! The flux: Cannont answer this without knowing what flux it is. Everyflux I have used has to be dry before it enters the wave. Liquid entering the wave solder process "spits" and creates solderballs, blowholes, voids, etc. Of a greater concern is the temperature shock you are subjecting your boards to; I have always used the traditional 100?C jump from last preheat to wave(bottomside temperatures) so that the components are not thermally shocked. Finally, process control. Who is in charge of the process? They should have developed a wave solder process, including defining preheat temperatures. If these two people are changing the process, then there is no control, and the quality of the process is suspect, beware of long term failures. The wave solder process requires a controlled process! It should not be changed by anyone, without the approval of the person in charge. The IPC and SMTA have numerous books in their catalog on wave soldering. Your questions are basic and you will find these answers and many others about wave soldering in these books. Ed Holton Manufacturing Engineer Hella Electronics [log in to unmask] on 02/13/98 10:23:27 PM Please respond to [log in to unmask] To: [log in to unmask] cc: (bcc: Ed Holton/Hella North America Inc.) Subject: [TN] To On or Not to On Hello, Can anybody please help or advice. I am trying to settle a dispute between my company's production supervisor and the maintenance technician on the wave soldering machine. 1) The maintenance technician insisted that the wave should be switched on and off between boards to prevent/lessen "damage" to the wave creation mechanism. (The wave can be switched on and off automatically by a sensor on the conveyor). My production supervisor think otherwise. She covered the sensor so that the wave would not be off.(She says the sensor can miss a board) So, who is right ? 2) My production supervisor sets the preheat to about 95 degree C so that the flux would not dry up when the PCB board reaches the wave and to increase solderability.(but this created a lotof residue on the solder bath,according to maintenance). My maintenance technician says the temperature should be about 120 degree C so that it dry up the flux before the board reaches the wave. The reason is so that not much residue is created. Who is right again ?? Thanks in advance. How Chee Malaysia ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################ ################################################################ TechNet E-Mail Forum 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://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################