Tip Style Selection

QA Technology offers a wide range of tip styles to support the various applications and test targets known in the industry. Experienced Test Engineers often have different preferences for the best tip styles to use on a given contact surface.

Below are general recommendations:

Pads:

When contacting gold plated pads use a, CHISEL or SPHERICAL so that marking is minimized. A SERRATED, CROWN or TRIAD are good choices for contacting clean flat solder pads, as they distribute the force over a greater area (reducing the likelihood of marking the pad) but require more frequent maintenance. Use a SPEAR, SHARP CHISEL, SHARP NEEDLE or RAZOR to increase tip contact pressure for reliable testing of heavily oxidized or flux-coated solder pads. QA does not recommend testing un-pasted pads. If necessary, use our 9R RAZOR or steel option for longer life.



image of various tip styles contacting gold plated pads

Holes or Vias:

Use a CHISEL or STAR to contact open holes. A CHISEL has fewer contact edges than STAR and therefore higher contact pressure. The CHISEL TRIAD is a good choice for contacting open holes where flux is present. The SPEAR is used when the rim of the hole must remain free of marks. Contact is made on a circle rather than on sharp edges. The BLADE and RAZOR will provide the highest penetrating pressure, since contact is made on just two sharp cutting edges. Although QA does not recommend testing on un-plated vias, the 6R RAZOR is the best choice.



image of various tip styles with unfilled vias

image of various tip styles with filled vias

For filled (pasted) vias, heavy contaminates require the use of a SHARP CHISEL or RAZOR. The RAZOR tips are especially designed for this type of application.


Leads:

Choose the tip style which will be most stable on the lead in order to minimize sideloading the probe and to extend probe life. The SERRATED is generally the most stable on long leads. The CUP can be used on extremely long leads but are likely to require more maintenance. A standard CROWN (valleys cut straight across the point) is more stable than self-cleaning styles (valleys sloping down and out). Tip styles with fewer tips or sharper internal geometry such as a TRIAD are best used on short contaminated leads. Smaller leads will require tip styles with closely spaced cutting edges to trap the leads. The Slotted CUP is designed to help prevent contaminate build-up.



image of various tip styles with leads

Terminals and Posts:

SERRATED or FLAT tip styles are stable on this type of contact, but have limited ability to penetrate contamination. Use a FLAT in clean conditions and with higher spring forces. A self-cleaning CROWN will require less maintenance than a CUP if used in an upward-pointing orientation, but are more likely than a CUP to glance off a post. A slotted CUP is best when used upwards, since a traditional CUP can easily collect dust and contamination from the Unit Under Test, they are best used in a horizontal or downward-pointing orientation.

image of various tip styles with terminals and posts

Solder Beads / Bumps / Domes:


image of various tip styles with solder beads, bumps, domes

A FLAT is the least aggressive and is used where minimal witness marks are desired. The MICRO-SERRATED tip styles are more durable and are recommended on points that have light flux residues. The FLAT STAR is self-cleaning and is used when a board will see high cycle counts. The CENTER POINT STAR is the most aggressive, making it ideal for no-clean flux processes where sharper cutting edges are needed.