Electronics Forum: corners (Page 5 of 66)

BGA Corner

Electronics Forum | Mon Jun 13 01:38:59 EDT 2011 | kenneth0

Hello Steve, i think you are experiencing the potato chip effect, where temperature difference at the center and edges are huge; causing BGA edges to tilt down or up.Try narrow down the temperature difference between the center of BGA and corner. I

BGA Thermal Profiling

Electronics Forum | Fri Aug 05 14:31:43 EDT 2011 | dmiller

Try a probe at two corners (opposing) and one on top. Provided your corners are getting comforatably into reflow temperatures, the middle should as well.

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

Electronics Forum | Tue Mar 21 20:36:11 EST 2000 | Dave F

Armin: Boca makes some good points about release. So, let me spin this up from a different angle ... SM-782 suggests "full radius corners" as an alternative to the more familiar square corner pads on PLCC, TSOP and QFP. We see both also. We thin

CCGA - Stencil design and Reflow Profiling

Electronics Forum | Wed Jul 31 07:51:31 EDT 2019 | ameenullakhan

Hi Dave, lead is 80Pb/20Sn. Top joint off CCGA lead is SN63/Pb37. Thermocouple was placed at center lead of the CCGA and one at the corner lead of CCGA. Ramp Rate Center 1.09 Corner 1.26 Soak ( 140 - 160 deg C ) Center 37sec Corner 38sec Ref

Re: Aperture size for Micro BGA stencil

Electronics Forum | Thu Jun 22 11:21:59 EDT 2000 | Chrys Shea

My personal opinion: Use 20 mil squares with the corners radiused at 5 mils. The squares offer 2 benefits: 1) A little more paste, which makes for a higher diameter solder column that is more reliable 2) Better stencil release of the paste. It's e

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

Electronics Forum | Mon Mar 20 20:22:47 EST 2000 | Dreamsniper

We used to have our PLCC,s, TSOP's and QFP's (0.65 mm pitch) Land Patterns designed in square corners. Some of our products have them designed in Full Radius Corners. As of now, with the two different designs running in our production floor, we can't

BGA with gold corner / reflow problems

Electronics Forum | Wed Jun 25 12:08:53 EDT 2003 | russ

I battle this all the time, I don't believe that it is the "gold corner" that is causing the problem but something with the PCB layer makeup (copper planes, or bottom side components, etc.). It could also be the nozzle you are using has a "hot spot/

MPM AP25, separation problems

Electronics Forum | Wed Nov 02 01:53:41 EST 2005 | pavel_murtishev

Hello, Thank you for answer. We are using second hand machine. What do you mean saying that �stencil is not height on all 4 corners�? Does it have some inclination between corners? I mean that three corners of stencil are matching with PCB fine and

Local Fiducials

Electronics Forum | Thu Oct 19 12:00:55 EDT 2006 | sliebl

Can anyone tell me if they are aware of any pick and place machines that can use 'randomly placed' local fiducials? Now, let me explain... Our machines (Contact 3S, and 3AV machines) can use local fiducials in several ways. We can use a single center

BGA chip corner epoxy / adhesive?

Electronics Forum | Wed Dec 06 22:46:39 EST 2006 | SMTrework

Hi Dave, This is manufacturer applied epoxy / adhesive to minimize package "lifing" from chassis flexing and thius board flexing. I have seen the complete array area covered with this black or red epoxy in some cases (i.e. the underfill that I've


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