I've had the same problem. We used a 10 mm pallet with a cap added to the bottom-side for the SMT connector.
This way we reduced the cost and reduced the thermal issues had we used a 12 mm pallet. Of course you can under cut the pallet to achieve a 10 mm one piece pallet. We opened up the other areas with wave pockets and added 1/2" wide solder relief grooves every 2.5 inches going around component pockets that had extra tall parts. The grooves run from the exit end to the entrance end of the wave.
In the 60's the groves in the pallets went from the fixed rail to the adjustable rail to get the solder moving over the "A" style waves. It pushed the dross and kept the wave going over the exit plate. The new nozzles or "wave fomers"aren't designed that way so the grooves weren't needed and pallets were made without them.
As new designs came out with more and more larger SMT components on the bottomside I had to address the pallet design again.
About fifteen years ago I started experimenting with putting the grooves back in, but in the direction of travel. This evened out the solder pressure to correct previous deigns that caused leakage where ever there were large connector holes like the ones for connector staking pins that were thin metal instead of the round plastic ones. A reduction of the solder pump speed caused insufficient solder fill in the areas with small openings for just that part and small openings for 2-4 pin headers in thick pallets.
With the waves pumping that hard we needed to control the flow on the bottom side and prevent solder going toward the conveyor fingers and splashing onto the top side. In later years these "solder relief grooves" provided an escape path for nitrogen applications as well. People using inerted nitrogen solder pots referred to them as "gas grooves". Then came the No-Clean fluxes which if you had round wave pockets and no grooves left a lot of dross bridges. Changing the wave pockets to rectangular and having the groove connect to the center allowed the dross to exit and not swirl around and stick to the leads.
Another benefit was that these solder relief grooves stopped the solder from shooting past the trailing edge of the pallet and going all over the last bottom preheater!
Another design tip is so look at thermal issues in the pallet design, open up or thin out areas for pins with large groud or voltage plains especially in the corners of the pallets where you have a lot of thermal mass. Some machine shops just cut clearance holes and wave pockets to make a pallet. You have to look at the board and design then establish a set of requirements to be forwarded to the pallet manufacturer. Ascentec Engineering, Insulfab Plastics and Stentech arewell established pallet manufactures that will apply the above features if you specify them.
Electrovert has the max component specs in the literature. The Hybrid wave is for PCAs, 6-8mm pallets. The Contour wave is better suited to PCAs all the way to 10mm pallets. They have the optional Deep Wave nozzle if you get a lot of boards that will require a 12mm thick pallet. Of course then you have to look at the clearance of your fluxer. If a foam fluxer then you have to lower it which will effect all your other setups. A spray fluxer is more tolerant. As you move up in moving more solder for thicker pallets you generatre more dross.
Selective Solder Systems as an Alternative to Wave Solder
Boards with designs requiring tall connectors and other parts on both sides are great candidates for Selective Solder Systems.
After wave you have to either use a lot of hand solder operators or use a Selective Solder System. Boards that can't go through wave without expensive pallets, generate a lot of dross which then increases downtime to maintain the system. The quality issues also increase with these types of boards in wave pallets. Combined it may cause you to look a Selective Solder System.
Low Cost Systems: Under $70 with one solder pot
-RPS Co and Ace Protech's, KISS 104 and higher (Keep It Simple Solder) has stepper motors and no Fid system cost high $60's,
- Seho's new Selective System with Servo motors (more precision/no backlash) and has a Fiducial Recognition for approximately $75K. These are great for Proto, medium volume or as supplemental to Wave Solder.
Both have optional 2nd pot for quick change to LF.
Higher Cost systems are: Vitronic MySelectives: gantry based systems $95K to $350K + tooling, all lend themselves to these bad designs. These can be configured to address volume speeds with Multiwave nozzles and systems with dual pots for two different size solder nozzles to do large and small parts in one pass. One configuration is to have single point nozzle pot and the Multiwave nozzle that can lower the whole board over the rows of dedicated nozzles and solder it in 8-10 seconds. Of course the dedicated nozzle plate ran me $8K and parts too closely spaced that would hit a nozzle and lift up. A couple of components may have to be hand soldered. Only the smaller Selective solder pot can be exchanged. For volume you would have a dedicated machine anyway.
I hope all this helps.
Subject: Re: [TN] Max height of components acceptable for wave pallets
There was a board that I worked on with a SMT connector height of 11mm (solder side) which needed to be covered with solder fixture (wave pallet/carrier). This thickness of the fixture covering the SMT connector was about 1mm, hence, in total it added up to about 12mm. The board thickness was 4mm so I worked with supplier to enable the machine to pump a wave height of 16mm. The result was ok but I still believed that it was a very poor work done on the PCB layout design.
As Ted mentioned the dross was huge..waste..
Do study the machine specification.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Whittaker, Dewey (EHCOE)
Sent: Wednesday, 11 March 2009 10:05 PM
To: [log in to unmask]
Subject: Re: [TN] Max height of components acceptable for wave pallets
You are probably going to be physically limited to 3/8th of an inch (0.375, 10mm). Most likely the wave dynamics to accomplish this will create a lot of dross.
Dewey
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Tuesday, March 10, 2009 11:46 AM
To: [log in to unmask]
Subject: [TN] Max height of components acceptable for wave pallets
Dear Technos,
What is the maximum height of the components on the solder side that will allow for using wave soldering masking fixtures?
Thank you,
Ioan Tempea, ing.
Ingénieur Principal Fabrication / Sr. Manufacturing Engineer
30 ans déjà! - Already 30 years!
950 rue Bergar, Laval, Québec, H7L 5A1
t : 450-967-7100 ext : 244
Mtl : 514-990-5762
f : 450-967-7444
[log in to unmask]
www.digico.cc <http://www.digico.cc/>
P N'imprimer que si nécessaire - Print only if you must
---------------------------------------------------
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
-----------------------------------------------------
---------------------------------------------------
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
-----------------------------------------------------
|
