LCC differences between LP Wizard and PCB Library

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Hi, 
I notices some differences in the IPC Most foot print generated by LP Wizard 10.5 (Mentor Graphics) and PCB Expert for LCCs.

For LP Wizard the goals are:
Toe: 0.55
Heel: -0.02
Side: 0.07
For PCB Expert the goals are:

Toe: 0.65
Heel: 0.25
Side: 0.05
Can any one provide some background on these changes. Is this because LP Wizard is using IPC-7351B and the PCB expert uses IPC-7351C? Is the difference something to do with the fact that B trimmed pads under components and C does not - or is this just for leaded ICs?

Any help would be appreciated.

Regards

Steve

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pcbsteve Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 27 Jan 2014 Status: Offline Points: 13	Post Options Post Reply Quote pcbsteve Report Post Thanks(1) Quote Reply Topic: LCC differences between LP Wizard and PCB Library Posted: 07 Feb 2014 at 4:50am
	Hi, I notices some differences in the IPC Most foot print generated by LP Wizard 10.5 (Mentor Graphics) and PCB Expert for LCCs. For LP Wizard the goals are: Toe: 0.55 Heel: -0.02 Side: 0.07 For PCB Expert the goals are: Toe: 0.65 Heel: 0.25 Side: 0.05 Can any one provide some background on these changes. Is this because LP Wizard is using IPC-7351B and the PCB expert uses IPC-7351C? Is the difference something to do with the fact that B trimmed pads under components and C does not - or is this just for leaded ICs? Any help would be appreciated. Regards Steve



Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(1) Quote Reply Posted: 07 Feb 2014 at 9:05am
	There were no solder joint goal changes between IPC-7351B and IPC-7351C. Here is the LCC solder joint goal chart that does not match any of the values you posted -
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pcbsteve Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 27 Jan 2014 Status: Offline Points: 13	Post Options Post Reply Quote pcbsteve Report Post Thanks(1) Quote Reply Posted: 07 Feb 2014 at 9:23am
	Hi, Thanks for reply on this. On closer examination it appears we were using the Oscillator option of the Mentor LP Wizard rather than LCC option. We have now change to the LCC option and the values now align. Thanks Steve

gelo_bun Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 04 Mar 2014 Location: Молдова Status: Offline Points: 12	Post Options Post Reply Quote gelo_bun Report Post Thanks(1) Quote Reply Posted: 10 Mar 2014 at 7:42am
	Hi guys, Please help me to understabd right, I'm beginer at this. I can’t understand, how the Performance Classification of products (Class 1 General Electronic Products, Class 2 Dedicated Service Electronic, Class 3 High Reliability Electronic Products) are connected with Land Pattern Determination(Density Level A: Maximum (Most) Land Protrusion, Density Level B: Median (Nominal) Land Protrusion and Density Level C: Minimum (Least) Land Protrusion), I mean each class can be combined with any of these three levels of density? can be combined or not class 3 with level C ? Thanks in advance! Sorry if I placed this question to other topic, but I didn't find a similar topic.

Tom H Members Profile Send Private Message Find Members Posts Add to Buddy List Admin Group Joined: 05 Jan 2012 Location: San Diego, CA Status: Offline Points: 5718	Post Options Post Reply Quote Tom H Report Post Thanks(1) Quote Reply Posted: 10 Mar 2014 at 7:48am
	Least, Nominal and Most for Library Expert just means the pad size and courtyard size are small, medium and large. This has nothing to do with Fabrication Class 1, 2 and 3. All 3-tiers in the IPC-7351 can be built to Class 1, 2 and 3 in fabrication. You need to talk to your manufacturer because they are the source that's building your boards and they set the Class per their manufacturing tolerances. i.e.: many fabrication shops can build a Least Library for Class 3 but some can't.
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gelo_bun Members Profile Send Private Message Find Members Posts Add to Buddy List New User Joined: 04 Mar 2014 Location: Молдова Status: Offline Points: 12	Post Options Post Reply Quote gelo_bun Report Post Thanks(1) Quote Reply Posted: 11 Mar 2014 at 12:37am
	Thanks a lot Mr. Tom , your explanation is very clearly for me and is helpful!