In table 9-3 on IPC-2222 it lists level A to C. The description of the three levels in on 1.6.3 Productibility level of IPC2221.
Level A General Design Complexity -- Preferred
Level B Moderate Design Complexity --Standard
Level C High Design Complexity ----- Reduced
Regards,
Ramon
> -----Original Message-----
> From: Donald Kyle [SMTP:[log in to unmask]]
> Sent: Wednesday, March 31, 2004 8:12 AM
> To: [log in to unmask]
> Subject: Re: [TN] Finished Hole Size vs Lead diameter
>
> This might be what you are looking for. Please excuse me if there is an
> error in this text as I'm still half asleep.
>
>
> Refer to IPC2221, section 9.0 & IPC-2222 section 9.2 for complete information.
>
> To find the minimum through-hole land size, a worst-case land-to hole
> relationship must be established. The following equation from IPC-2221
> will do that.
>
> Where:
> Copper weight = 1 oz and number of layers are 8 or less. (see table 9-1 in
> IPC-2221)
>
> For internal layers:
> a = the drilled hole diameter ( see table 9-3 in IPC-2222)
> For external layers:
> a = maximum diameter of the finished hole (see table 9-3 in IPC-2222)
>
> b = minimum annular ring requirements = 2 mils
>
> c = standard fabrication allowance = 8-16 mils (see table 9-1 in IPC-2221)
>
> For example, take a 20 AWG wire that is 38 mils in diameter at its maximum,
> 8 layer PWB.
>
> The maximum diameter of the finished hole would be 38 + 6 (hole to lead
> space) + 3 (tolerance) = 47 mils. The nominal diameter would be 38 + 6 =
> 44 mils.
>
> The drilled hole diameter is 44 + 6 = 50 mils.
>
> Minimum through-hole land size = a + 2*b + c
> Internal land = 50 + 4 + 10 = 64 mils
> External land = 47 + 4 + 10 = 61 mils
> Remember, these are the minimum land sizes and they can be made larger.
>
> In IPC-2222, section 9.2.2 Plated-Through Holes, the minimum and maximum
> finished hole size is discussed. It states that the maximum hole size is
> less than or equal to the minimum lead diameter plus 28 mils (level A) and
> that the minimum finished hole size is greater than or equal to the maximum
> lead diameter plus 10 mils (level A).
>
> The following methods calculate the minimum land size for a typical
> DIP-I.C. with leads as follows. Width = (15 mils 23 mils), Thickness = (8
> mils 15 mils), Diagonal = (17 mils - 27 mils).
>
> Using the IPC-2221 formula
>
> For internal lands
> Minimum land size = a + 2*b + c
>
> Where:
> a = drilled hole diameter
> b = minimum annular ring
> c = fabrication allowance
>
> drilled hole diameter = maximum diameter of finished hole +6 mils (depends
> on type of finish).
>
> a = 51 mils
> b = 2 mil (internal)
> c = 14 mils (8 layers or less)
> c = 16 mils (10 layers or more)
> c = add 2 mils/oz of Cu for Cu > 1oz
>
> Number of Layers 10 8
> a42 mils42 mils
> 2*24 mils4 mils
> c16 mils14 mils
> Min land size =62 mils60 mils
>
> Using the IPC-2221 formula
>
> For external lands
> Minimum land size = a + 2*b + c
>
> Where:
> a = maximum diameter finished hole
> b = minimum annular ring
> c = fabrication allowance
>
> maximum diameter finished hole = minimum lead diameter (17 mils) + 28 mils
> = 45 mils.
>
> a = 45 mils
> b = 2 mil (external)
> c = 14 mils (8 layers or less)
> c = 16 mils (10 layers or more)
> c = add 2 mils/oz of Cu for Cu > 1 oz.
>
> Numbers Layers 10 8
> a45 mils45 mils
> 2*24 mils4 mils
> c16 mils14 mils
> Min land size =65 mils63 mils
>
>
>
>
>
>
>
> At 09:26 AM 3/29/2004 -0600, you wrote:
> >Fellow TechNetters,
> >
> > Can someone guide me to an IPC document that make reference to
> >Finish Hole Size
> >versus lead acceptable lead diameter with respect to ROUND, RECTANGULAR
> >and SQUARE
> >Leads. I have a case in which the square lead deformed the PTH and
> >minimal solder
> >fillet is exhibited inside the barrel. At least in my opinion.
> >
> >In advance I thank you for your timely response in this matter.>
> >
> >Victor,
> >
> >---------------------------------------------------
> >Technet Mail List provided as a service by IPC using LISTSERV 1.8e
> >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
> >847-509-9700 ext.5315
> >-----------------------------------------------------
>
>
> Donald Kyle C.I.D.+
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e
> 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 847-509-9700 ext.5315
> -----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
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 847-509-9700 ext.5315
-----------------------------------------------------
|
