Solder bead/bump technology places test points on pasted traces that has solder mask removed. This technology was developed to provide test point accessability, utilizing a large headed probe to contact a small solder bump that is placed on the trace. Since the solder bumps on the traces can be staggered, it is not necessary to route traces to accomodate conventional test pads.
QA Technology offers a variety of headed and headless tip style designs for probing solder bead/bump/dome targets. Headless tip styles are for applications where nearby components are located too close to the intended target, or where the fixture utilizes a guided probe plate.
Flat 10 and 20 tip styles have a smooth flat face and are the least aggressive tip designs. These are recommended for clean processes where a minimal witness mark is desired.
Micro Serrated 59 and 79 are moderately aggressive with small serrations running across the face of the tip. This durable tip is more aggressive than the Flat 10 and 20 tip styles and will work with contact points that have light flux residues.
Flat Star 16, 36 and 46 tip styles have deep radial grooves extending from the center which makes them self-cleaning. These are recommended for clean and no-clean flux systems. The deep channels are designed to handle heavier flux residues. This moderately aggressive tip style is also recommended when a board is going through debug and the board will see high cycle counts/re-tests.
Center Point Star 26, 47 and 76 tip styles are the most aggressive making them ideal for no-clean flux processes where sharper cutting edges are needed. The sharp radial edges along with a sharp center point tip minimizes the contact area which allows them to penetrate deeper into the solder bump. The self-cleaning design forces flux away from the cutting edges.