Shawn,
 
J-STD-001 generally addresses conventional manufacturing processes like the automated mass solder wave process. I am assuming you do not have components on the secondary side (bottom). There are multiply reasons why you would not solder PTH components on the primary side (topside) of a PCB in the manual hand soldering operation: 
1. Components can obstruct your ability to achieve good tip to pad contact.
2. Risk of applying to much heat since you are soldering closer to the component body.
3. Harder to clean flux residue when components shadow the pads.
4. The lure of touching up (soldering) on the bottom side when a defect is detected on the bottom of the PCB during inspection. This could cause entrapment of contaminants or create a void.
 
Did you know that it is desirable to have solder in the clinched area? It provides additional mechanical support.
 
There are plenty of devices (foam clamps) and masking materials that can be used to restrain parts so you can solder from the secondary side. 
 
Instead of using a full clinch to the PCB, try a partial clinch 45 degrees. 
 
 
Evamaria Jones 
Quality Assurance Specialist
Electronic Manufacturing Skills Instructor
General Dynamics Information Technology
(703) 874-6796 direct 
(540) 522-8823 cell
[log in to unmask]
www.gdit.com <https://owandhm.gd-ns.com/exchweb/bin/redir.asp?URL=http://www.gdit.com/> 

________________________________

From: TechNet on behalf of Upton, Shawn
Sent: Tue 5/29/2007 9:08 AM
To: [log in to unmask]
Subject: [TN] Clinched Leads



I have a copy of IPC-A-610, and PC-2221A, but neither gives me the
answer I'm looking for at the moment.  Soldering leaded components is
(usually) done bottomside; is it verboten to do topside soldering so as
to avoid clinching leads?  I find it much harder to replace components
when clinched.  I know electrolytics it can't be avoided for, and mono
caps probably shouldn't be topside soldered (they change color nicely);
but for resistors with nice long lead spans, is it a problem?  [8.1.11
in IPC-2221A]  I'm talking hand assembled boards, long-ish life (a few
years) but not space/life support/high temp/low temp/high speed designs
(test equipment).

Shawn Upton, KB1CKT
Test Engineer
Allegro MicroSystems, Inc
[log in to unmask]
603.626.2429/fax: 603.641.5336

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