Roger
Thanks for your concern,i have read the suggested sections but i have not
noticed a big difference,
However you told me about skips and voids problems that can be existed if
the clearance value is larger than 0.5mm,
could you refer me to any reference document said that to proof this concept
for our assembler who have requested me to increase the hole diameter
for all padstacks in the library because he claimed that they are narrow for
the inserted lead components (although our padstacks library meet the
standard clearance).
Thanks a lot
A. Sunhoury
Pcb Designer
R&D Dept.
www.bahgat.com
> ----------
> From: Roger M. Stoops[SMTP:[log in to unmask]]
> Reply To: DesignerCouncil E-Mail
> Forum.;[log in to unmask]
> Sent: Monday, March 12, 2001 4:37 PM
> To: [log in to unmask]
> Subject: Re: [DC] Diameter of Unsupported Hole
>
> Ahmed,
> What the IPC specs don't say is that for automatic insertion, the hole
> size
> may need to be larger than the IPC maximum spec (IPC-2222, Section
> 9.2.1.1). In the IPC Certification study guide, it says that clearances
> up
> to 0.7mm can be used. Anything over that will typically cause problems.
> Also be aware that clearance values larger than 0.5mm can cause problems
> when soldering, such as skips and voids. Leaded insertion machines
> typically need a clearance anywhere from 0.4mm to 0.7mm, depending on the
> manufacturer and the part being inserted.
> I would suggest that you get IPC-2221 and IPC-2222 for future reference;
> they superceded D-275 three years ago.
> The spec for unclinched leads is IPC-2221, section 8.3.1, but it doesn't
> give any clearance data.
> Hope it helps,
> Roger M. Stoops, C.I.D., PCB Designer
>
>
> Trimble
> Engineering and Construction Division
> 5475 Kellenburger Rd.
> Dayton, OH 45424-1099 USA
> Ph: +01 937.233.8921 or +01 937.233.4574 ext 288
> Fax: +01 937.233.7511
>
>
>
> Ahmed
> El-Sanhoury To:
> [log in to unmask]
> <[log in to unmask] cc:
> AHGAT.COM> Subject: [DC] Diameter of
> Unsupported Hole
> Sent by:
> DesignerCouncil
> <DesignerCouncil
> @IPC.ORG>
>
>
> 03/11/01 10:45
> AM
> Please respond
> to
> "DesignerCouncil
> E-Mail Forum.";
> Please respond
> to Ahmed
> El-Sanhoury
>
>
>
>
>
> All
> I would like to verify about the clearance value-0.5 mm-that should be
> between the Unsupported Hole and the lead diameter of component as
> IPC-D-275
> said at (Page 70 Sec. 5.4.6.1 Diameter of Unsupported Holes),
> is this practical value?,In fact it seems to our assembler a small value
> to
> insure that the Automatic Insertion Machine insert the components
> properly,
> i wonder if he is right or there is somthing error on his process
> (such as the Hole location determination, the accuracy of the machine or
> somthing else),Moreover, in case of clinched component what the clearance
> value should to be? (as IPC-D-275 in Sec. 5.4.6.1 refer to it but it does
> not continue the information "....., Unless it is clinched"), Thanks in
> advance.
>
> A. Sunhoury
> PCB Designer (Electronic Engineer)
> www.bahgat.com
>
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