Electronics Forum | Thu Feb 02 09:07:28 EST 2023 | charles_nguyen
Two types of land patterns used for surface mount pads are non-solder mask defined or NSMD pads and solder mask defined or SMD pads.Each type has its own advantages and disadvantages. There is a statement that SMD pad type may introduce stress concen
Electronics Forum | Wed Feb 08 09:43:08 EST 2023 | charles_nguyen
Thank you for the above information but what I want to talk about is the PCB design aspect. Should there be any warning about it in the DFM?
Electronics Forum | Wed Aug 10 13:31:05 EDT 2005 | patrickbruneel
Joseph, In addition to my previous post The reason why the cracks are most visible at the transformer location is due to the weight of the transformer. The stress on the boards is the highest because the weight of the transformer will warp the board
Electronics Forum | Mon Aug 01 09:06:33 EDT 2005 | davef
Based on your description, it sounds like the solder connection is defective. Further description of board and solder materials and assembly processes would be helpful in moving forward.
Electronics Forum | Wed May 26 18:04:16 EDT 1999 | John Thorup
| After reflow proces in convection-IR oven we find broken body of SOT23 elements. There is no problems on other elements (SOIC, chip R,chip C, etc) | Where is the problem? | | Thanks in advance! | Check your profile at the site of cracked component
Electronics Forum | Mon Aug 01 08:38:57 EDT 2005 | kamrant
Joseph, What is the topside temp reading of your board before reaching the pot? Do you have top-heater in your wave machine? It sounds like; you got an insufficient per-heating issue.
Electronics Forum | Fri Feb 17 19:23:05 EST 2023 | SMTA-64387083
Read the articles everyone else recommend. I haven't read of them but I will say this. A Solder Mask Defined pad is a copper flood that has much more thermal mass than a Non-Solder Mask Defined pad so it will heat and cool at a slower rate. I suspect
Electronics Forum | Fri Feb 20 08:44:05 EST 2004 | davef
Lucky guess, eh? [Sorry to blow your theory on bad parts] A 1000 of these boards on the line, ummm. Two ideas to consider: * Increase the conveyor angle [don't get carried away, just keep the angle below 8*]. * Balance the flow of solder so that th
Electronics Forum | Fri Feb 20 12:55:43 EST 2004 | russ
Ah, the old contour wave. I don't really know how to adjust those to get correct backflow to reduce your solder volume. I need to ask why you are worried about this. Do you have a QC requirement in excess of IPC class3 wich allows for this joint t
Electronics Forum | Thu Feb 19 09:02:43 EST 2004 | russ
This is a pretty common sympton when wave soldering chip components. As a note IPC allows for this in wave process. The problem is in the pell off of the wave and you may not be able to fix. Is your back flow off of the wave only present when a bo
