Electronics Forum | Mon Jun 14 14:30:42 EDT 1999 | Deon Nungaray
| | | | | Hello all! | | | | | Recently we got a problem about the Funtional test. Some boards passed tests by using the auto-fixture(vacuum), but failed by using manual test fixture(need to plug CPU, DIMM etc.). The error symptom is no picture. We d
Electronics Forum | Tue Jul 20 16:02:12 EDT 2010 | mikesewell
You may want to look at IPC 7721 Method 3.2 Bow and Twist Repair. In extreme cases you may need clamp or weight the pcb with bow in the other direction to yield a "flat" pcb in the unrestrained state. You will have to take the PCB up to or slightly
Electronics Forum | Sun Apr 10 06:27:50 EDT 2005 | WarpSpeed
1.) First of all: What is Your customers requirements??? 2.) If the customer or You don't have a specification; I will strongly recommend that you follow the "IPC-IPC-TM-650 Method 2.4.22 Bow & Twist" that [DaveF] suggested. 3.) If You have "critic
Electronics Forum | Tue Nov 16 18:02:29 EST 1999 | John Holland
What are the main advantages of moving from a 140 degree C FR4 laminate to a higher Tg laminate 180 degree C ?. Would the higher Tg laminate be less susceptable to bow and twist ?. John Holland
Electronics Forum | Fri Jun 11 03:39:26 EDT 1999 | Gyver
| | | | Hello all! | | | | Recently we got a problem about the Funtional test. Some boards passed tests by using the auto-fixture(vacuum), but failed by using manual test fixture(need to plug CPU, DIMM etc.). The error symptom is no picture. We doubt
Electronics Forum | Mon Nov 01 15:35:25 EST 2004 | Ken
Agreed. You will find different part manufacturers have different coplanarity specs. In fact I have on supplier that calls out 7 mil max coplanarity. Then factor in board bow and twist and it becomes a real joy.
Electronics Forum | Fri Apr 08 05:10:10 EDT 2005 | siverts
What is Your customers requirements? Is the PCBA mounted with front/back connectors? Will the PCBA be mounded in a rack and connected to opposite connectors on the other side? In this case, if the warpage is more than approx 1-1.5 % You will then n
Electronics Forum | Mon Nov 20 19:49:03 EST 2006 | davef
Sorry for stating this incorrectly. It should been: Bow & twist for bare boards and panels: IPC-A-610 Acceptability of Electronic Assemblies, 10.6: 1.5% for PTH only and 0.75% for SMT, acording to test method TM-650, method 2.4.22 IPC-6012, par. 3.
Electronics Forum | Thu Jun 10 14:52:55 EDT 1999 | Earl Moon
| Hello all! | Recently we got a problem about the Funtional test. Some boards passed tests by using the auto-fixture(vacuum), but failed by using manual test fixture(need to plug CPU, DIMM etc.). The error symptom is no picture. We doubt it's the pr
Electronics Forum | Fri Jun 11 04:38:05 EDT 1999 | Gyver
| | | | | Hello all! | | | | | Recently we got a problem about the Funtional test. Some boards passed tests by using the auto-fixture(vacuum), but failed by using manual test fixture(need to plug CPU, DIMM etc.). The error symptom is no picture. We d
