Mark McMeen

Mark McMeen has submitted responses to the following questions.

Trays for MLS Baking
Glass is an insulator and given the right conditions the glass surface can hold an electrical charge. Glass is not ...

Question About ESD Ionizer Guns
Yes, Ionizer air guns are used to minimize positive and negative ions on the surface of the PCB assembly and ...

Baking Concerns for Stacked Trays of Components
We also bake parts out on a regular basis and I assume you are using standard trays which stack and ...

Selective Solder System Purchased At Auction
Very good question and you have two choices. Buy a second pot for your machine and make it the Lead ...

Concerns With Silver Finish Component Leads
Really good question - would have liked a little more information but here is an answer I think addresses why ...

Cleanliness Testing
I would recommend using an ion chromatography approach to quantify and qualify the amount of ionic contamination present on the ...

Dendritic Growth and Contamination at BGA Sites
My suggestion is to remove BGA's and clean the boards in a water wash or solvent cleaner after removing the ...

Type 4 Solder Ball Use
There is no downside to using type 4 paste. You will get a larger metal content due to metal load ...

Mixed Technology - Which First
We always smt first and then thru hole for repeatability due to thru hole component size issues. SMT components are ...

Organic Flux Residue Concerns
The answer lies in what type of organic residue is left. My recommendation is to have an ion chromtagraghy analysis ...

SMT Component Lead Oxidation
The answer is to retin the leads to remove the oxidation and prepare the leads for the SMT operation. A ...

Delamination dilemma
Please review your bake out time and temperature for your bare boards. Rule of thumb is 105C for 6 hours ...

Cutting inner layer circuits
Please insure all technicians are trained to the 7711 / 7721 rework standard and have proper certification training. The drills ...

Reworked BGA component bridging at the corners
The short answers is bga's can be reballed and replaced. We do it all the time for clients and we ...

Technology to Measure Oxidation Levels
The answer is the use of a Wetting Balance Tester to determine the wet ability of the surface mount leads. ...

Nickel Barrier Thickness Requirement
The rule of thumb is no lower than 100 microinches and the nominal should be 150 microinches. It is ok ...

Wave solder process issue
Dewetted / unwetted solder is a sign that the solder alloy does not like the surface of the pads in ...

BGA Replacement limit
There is no hard industry rule but the rule of thumb for most companies is no more than 5 to ...

Pre-Bake Standard for Rework
The rule of thumb used by us in our rework area for FR4 and Kapton based materials is 105 degrees ...

Procedure for Baking Flexible Circuits
This is a very good question and most people have different views but I am an old flexible printed circuit ...

Lead frame contamination
The answer is really a 2 part solution to this request. First, Lead frames need to be free from all ...

Opens on BGA solder joints after reflow soldering
The answer to the question is the development of an analytical test protocol. The substance needs to be identified – ...