BGA Secondary Reflow Ball Seperation

Secondary Reflow & How BGA Balls Separate Here is a video clip I have wanted to make for some time as I have helped customers with this issue on many occasions over the years. Basically, our video shows reflow at the top of the joints and then part separation. The sample was rough ground to a midpoint on the samples then heated from both sides with the aim of showing the separation. There are of course a number of reasons this can happen in wave, selective, rework or on double sided assembly. The problem is they may be intermittent during the life of the product and difficult to find Basically I did a standard lead free BGA reflow simulation with a little more heat to the top of the component to get reflow starting at the package interface. I have done the same on the board side but not what I wanted to show This type of experiment was conducted by other engineers in their case they also measured the movement of the balls and package in a detailed study. A little out of my equipment capability and time budget If I shoot these again I will spend a little more time and decrease the grit size in the paper used but I did want the uneven surface to make it easier to see the change in state of the solder due to the reflection of light. The next experiments are on Low Temperature Solder Joints

Bob Willis Coating Defect of the Month 2019

Bob Willis Defect of the Month explains variation in coating under UV inspection lights? Bobs webinar guide to conformal coating and inspection is available online and covers all of the different solutions from his archives see https://www.bobwillis.co.uk/product/online-webinar-archive-booking/ The video is just one of the Defect of the Month videos featured by IPC, SMTA and Circuits Assembly to help provide better understanding of process issues and help support training of younger engineers Past Defect of the Month magazine pages are available online at Circuits Assembly magazine or the videos at https://www.youtube.com/user/MrBobwillis

Great Easton Soapbox Race 31 Aug 2019

Great Easton Soapbox Race 31 Aug 2019 Here are the thrills and spills of the Soapbox Race, only in England can you go to village fetes and exciting events like this. All organised by volunteers and have some great fun and contribute As I said to two of the organisers when I arrived it looked like a very professional event and Team Easton should all be very proud of the day which must have been months in the planning

Diving in Barbados 2019

Diving again, its a hard life but someone has to do it. A pleasure and great fun in Barbados and staying at Sandals. Here are some of the video clips from this year’s trip to the island Hope you like the fish clips I have done my best to select a varied selection from my dives around the island Videos and still images taken with GoPro 5 and Olympus TG5 without housing both with orange filters. Happy to try out the new GoPro or TG cameras on my dives Bob Willis bob@bobwillis.co.uk

Essex Dog Day at Crix Chelmsford Essex 2019

A great new feature at this years event. Great hot weather but not ideal for all of the four legged visitors

Chelmsford City Walking Football 5th September 2019

Highlights of matches for the over 65 in Harlow. Hopefully in a another couple of months I can be playing again. If the sun is not shining you will not be able to see if I run

Walking or Running Football 2019

September 5th Walking Football in Harlow Many thanks for some comments, yes you are right there is some running in some matches but in each case in the first match the referee picked up the players for running. As a few people ask the question we at CCWF always use walking football trained referees. We have created a training video for any WF team to use and a set of colour posters we are happy to provide to other teams Just for fun and as it was a very sunny day I have gone through the clips frame by frame and selected where people would be picked up or not for running. I have only gone through the first half of the first match but it does illustrate the point. The rule as in Olympics is one part of the foot must be on the ground, the sunny day creates very distinct shadows so easy for me to spot and highlight. But still very difficult for the referees when people can walk fast Many thanks again for your comments