There are several reasons to use teardrops:

• It reduces mechanical & thermal stress where the trace joins the pad resulting in less hairline cracks in traces.
• It enlarge the PCB manufacturer tolerance of the drill to pad.
  This make the production of a board easier.
  And reduces rejected board during production.
  All of this in turn could reduce the total price of a complex board.
• Reduces risk of cracking
• Improves resistance to thermal shock mostly effecting rework and wave soldering during production.
• Improves resistance to thermal shock of the product if found in rush environment.
• Improves resistance to impact shearing.
• Some say that:
  for BGA, the use of teardrops, with none solder mask pad, provides additional ball-to-land contact area, making them more mechanically robust.
  It make sense – but we do not support nor recommend it.

Some of the important location to apply teardrops:

• It is important mostly for thru hole drills where the trace to pad ratio is small.
  For military dense board where the annular ring around vias should be kept
• On flex-PCB layouts to reduce the stress where the trace joins the pad.
  Adding tear drop under BGA (where you have lots of vias) see figure 1
• Teardrops should be added when traces exit the pad whether it is a solid pad or a pad with a via.
• The importance of adding a teardrop grow as the trace become narrow
• It is not necessary to add teardrop for conductor bigger then 20mil

How and when to add the teardrops

• It is always better, and we recommend to ask the PCB layout Office to do the teardrops at the final stage of design.
• This way you get the same result with any PCB manufacturer how will produce your board.
• In some cases, this feature is simply a check box on your CAD system or something that your PCB designer will do for you- you just have to ask.
• In RF or high frequency boards, It is important to have full control of your PCB layout. Teardrops should be added at the design stage itself.
• The PCB manufacturer have Teardrop creation engine. When auto teardrop creation is allowed to the PCB manufacturer, teardrops connections can be made so DFM routes will be kept.
• In any case we recommend you design with tear drops or give acceptance to PCB manufacturer to add tear drops.
• In some cases a teardrop cannot be added, most CAD software “know” when to add and when it not possible to add teardrop, not need worry about that.

Signal Integrity and Teardrops.

• Information under this section are not confirmed by our engineers:
  • A teardrop shape pad typically only recommended for frequency above 1 GHz.
  • The extra capacitance of the teardrop shape balance the effect of the inductance associated with a via.

What type of teardrop to add:

• One way (called “snowman”) is to add secondary pads at the junction of an existing pad and the trace, the secondary pad is smaller than the primary pads, and the center is placed few mils away from the center of the primary pad.
• The other more common way is called Filleting or Straight, several trace are added from the existing pad towards the existing trace.

Figure 1

	Without tear drop	With tear drop
Board without drill deviation
Board with drill deviation

Prepared By Amos Kolath