3 years ago, it was in 1999, I bought Kester Precision solder paste type WS860, in a seringue of 25g. It was kept in a drawer of the refrigerator up to today. I followed the recommendations. 1) applied a strip of paste along all the contacts of all SMD components, even 0805 resistors, capacitors and transistors. 2) Carefully positioned all the components over the paste, trying to targ= et the SMD pads. 3) It got all messed up, everything short circuited, included resistors, ICs, etc. 4) Carefully put the board in middle of a regular kitchen electric oven (this oven is at least 8 years old, the temperature control is not anymor= e precise as you can imagine). 5) Applied two hundred something (2XX =B0F) during 4 minutes, then increa= sed to aprox 350=B0F during 2 minutes, and finaly 450=B0F during 1 minute. 6) Imediately turned off oven and open door very carefully to not bounce = or shake the oven - all components are just positioned with melted solder, then can slip out of place very easily at this moment. 7) Helped to cooled down the interior of oven a bit, using a small card board as a manual fan. A small fan air flow applied from outside could help. 8) After one minute, removed the (hot) board and left to cool down for mo= re 2 minutes. From aproximately 350+ SMD pads, only 4 or 5 solder bridges were observed= , easily removed with a hot solder iron 0.5mm tip. Checked all resistors and capacitors for no short circuit (solder could bridge beneath them), all was ok. Even the mess created by solder paste during component application just disappeared, and everything is as beautiful as a professional production. I got surprised that this 3 years old solder paste still working, I heard somewhere that solder paste has a short life span. I think the regrigeration kept it "alive". Obviously I will rush to buy a new kitchen oven, install a temperature sensor and control everything now by the use of an AVR and a large TRIAC. Without messing with the actual oven controls, the idea is to set the ove= n to max temperature (500=B0F) and then control the lower temperatures by t= he use of the AVR, Temp sensor and the TRIAC. The actual way the oven controls temperature is by a bimetal system, it i= s good only for cooking food, since the flutuation of the oven by a bimetal control is in large chunks of temperature. The TRIAC with a phase angle system control will give me a better temperature stability for the system. Of course I will bring the new oven in a gift box for the wife... ;) Double bonus, hmmm? Wagner. Alexandre Guimar=E3es wrote: > Hi, Wagner > > It is as simple as it gets... Buy them in syringes and use air > pressure and time control. Easy to make your own and you only need a > regulator to about 25 psi. > > Best regards, > Alexandre Guimaraes > > ----- Original Message ----- > From: "Wagner Lipnharski" > To: > Sent: Monday, November 18, 2002 2:46 PM > Subject: Re: [EE] Hot air soldering =3D cheap was Re: [EE]: Printer to > PCB? > > >> Scott Touchton wrote: >>> Actually.... 450F for 2 min in a toaster oven works real well with >>> the Kester 276 paste. >>> >>> Doing this right now in my basement, and I have a friend who owns a >>> small electronic company that has done this for the last 10 years. >>> >>> Neat thing about small ovens is that they can really follow a nice >>> pre-heat / reflow curve on their own! Start them out at 150F, then >>> hit the power and let them ramp on their own. >> >> how do you apply the solder paste? stencil system? or the continuous >> stripe over the pads with lots of solder paste? or other? >> >> -- >> http://www.piclist.com hint: PICList Posts must start with ONE topic: >> [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads >> >> > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads /_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ Wagner Lipnharski - UST Research Inc Orlando FLorida - USA - www.ustr.net /_/_/_/ Atmel AVR Consultant /_/_/_/ -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads