Genetic Circuits

APPLE ATI VIDEO CHIP Technical Correspondence

Bobby /  Paul,

I am going to give you guys my business, economic and technical opinions and guidelines and want you guys to handle the rework project accordingly.

Here is where some process engineering work is needed.  We have identified a very  clear issue with the inconsistent solder on the Ibook video BGA. I agree with your analogy of both concave and convex solder joints except that I dont believe solder is migrating into any vias. (Unless the Xray shows that the vias between the solder balls have solder in them). I havent looked at any, but rarely does the mask breakdown unless it has been wicked over once or twice during a re-surface process. I believe that this is the result of inconsistent paste deposition either from a poorly controlled printing process

OR - CHECK OUT THIS CONCEPT: I have discovered that ATI Radeon Mobility video chips on a variety of products have had this intermittent fractured solder joint problem. It is possible (not certain) that the packaging engineers at ATI specified undersized apertures for their recommended solder paste file.

I would like to have one of you locate the datasheet for the ATI Radeon Mobility Chip for two reasons: 1) I would like to review the recommended aperture sizes for solder paste deposition 2) I need to get the mechanicals for possibly using preforms to reball.

I have probably between 85-95% success rate by just reflowing the BGA for the customer. I am confident this rework will give them 1-2 years, and possibly as much functional life out of their laptop as they had before it broke. It is, as mentioned curing the symptom (broken solderjoints) but not the cause (inconsistent solder joint size).

I dont think we're going to get into re-balling these unless I find there is a market for it which I will research. I may reball the Ibook that is there with Bridges on it just to do an analysis /reliability test. Anyway.....if a complete reball was the answer to both the symptom and the cause, the customers threshold of pain is $75 and I actually see our cost with burden rate around $100. So we would need to research some alternative to the plate reballing method (possibly use pre-forms).

Regardless of whether we reflow or reball, we need to verify that the new rework station has the correct parameters entered. You need to get a 5mil thermocouple from the SlimKic box in the SMT area. The thermocouple that is currently plugged in to the BGA 3000 is too short. Then slide the thermocouple beneath the BGA on a scrap motherboard, (use the one with the fried components on the end of it). If you want to get even better contact there is a thermally conductive adhesive the SMT area for attaching thermocouples. I believe there are reference profiles in the Slimkic manuals for 63/37 solder paste. If not, here is a reference: http://media.maxim-ic.com/images/appnotes/3377/3377Fig06.gif

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Tom McCarthy
First Phase Technologies
2640 W Medtronic Way
Tempe, AZ 85281
480-967-1100 W
480-283-3205 C

Apple Ibook Repairs/ Inspection Scope

I want to mention to all the loyal customers of my Apple ibook video repair service, (and potential new ones) that I have just purchased a high powered BGA inspection scope. This new scope will allow me to view beneath the BGA device to identify the condition of the BGA solder joints when it arrives from the customer, as well as the how the same solder joints look after we reflow the device. Check back here soon for images that will shed some light on this very common manufacturing defect.

By the way, I was reviewing some of the Apple forums regarding this issue. It was interesting to see what some people are doing to repair this problem. In one article a guy used candles and some flammable liquid (I cant recall what it was). There were pictures of the motherboard with huge flames coming off of it! Pretty wild what some of these hardware hacks will do to get their hardware working. When I see this stuff I wonder if its the cost of a new PC or just the thrill of  performing surgery on your own hardware to save its life!! Either way , we appreciate the business. By the way, send me your motherboard before you try to light it on fire, not after. Please don't try the heat gun or propane torch then call us, it often does irreversible damage.

Best

Tom McCarthy

First Phase Tech