Electronics Forum: land patterns change cause (Page 1 of 10)

Min spacing for land patterns from PCB edge

Electronics Forum | Tue Mar 18 12:38:39 EDT 2008 | fsw

Hi! Can anyone tell me what is the min spacing between PCB edge & land pattern to avoid cracking of components due to mechanical stresses caused while depaneling with cookie/pizza cutter. Thnx!

Stencil deformation patterns

Electronics Forum | Tue May 22 02:27:50 EDT 2018 | bukas

there are numerous factors: -stencil age -stencil finish and thickness -stencil-board vertical alignment -board support -squeegee pressure -squeegee blade material and condition question here is did stencil changed its dimension over time? ar

Stencil deformation patterns

Electronics Forum | Wed May 23 15:58:01 EDT 2018 | mcurtin2011

Those patterns are either: a) the stencil has recieved some streching stress - either being pushed on and dented by some obstruction, or b) has been worn thin and therefore streched as a result. This type of change to your foil may cause a slight sh

Re: Land patterns for 0612 and 0508 capacitors

Electronics Forum | Tue Nov 30 21:23:55 EST 1999 | cklau

hello; When we are doing component land pattern design , one thing will always be in our mind; that is the basic criteria or common land pattern design guideline for reflow and flow solder assemblies. For basic fomula in calculating resistors are:

SMD pad definition may cause solder joint cracking under extreme fatigue conditions.

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

Re: Tombstoning

Electronics Forum | Tue Feb 23 09:09:34 EST 1999 | Steve Schrader

| What to look for that causes tombstoning and the corective action. | Check your land-patterns. If they do not meet IPC standards, change your CAD libraries to IPC (or some other industry accepted standards such as SMTPLUS). If you have "home-gr

Re: Land Pattern Design for PLCC's, QFP's etc... in Full Radius Corners

Electronics Forum | Wed Mar 29 22:30:13 EST 2000 | cklau

Hi guys; There are a few points that should be taken in to considerations regarding IPC-SM-782 land pattern and design rules. As a general rule all SMT reflow pattern should be in comply with SM-782 but however for special cases like : * PLCC land

How to avoid tombstoning in 0201 components

Electronics Forum | Tue Jul 05 13:54:35 EDT 2005 | Sandeep

We are facing lot of problems with tombstoning in 0201 components. Ironically tomstoning in these components is not occuring while reflow but it is happening when we subject them to thermal cycling test. We have been investigating the cause and thoug

Stencil design for dpack

Electronics Forum | Fri Jan 19 06:52:36 EST 2001 | pteerink

We have had the same problem with several boards, and the problem was with the land pattern design on the PCB, not the stencil. We found that the part tends to center itself on the one large pad, and if the two smaller pads are not the right distance

Need advise on regarding Vias

Electronics Forum | Mon Dec 13 00:48:33 EST 1999 | armin

Hi All I have a 0.7 mm diameter hole for vias, what�s the minimum annular ring for this hole diameter? What�s the term unsupported and supported holes refer to in IPC-2221 9.1.2 Annular Ring Requirements? I have a proto-type PCB (designed by our R&

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