PTH Repair - How to Select the Right Eyelet

Cross section of PTH repair using an eyelet.

One of my favorite circuit board repair procedures is no. 5.1 Plated Hole Repair. Even in today's high tech world there are still thousands of circuit boards being used that were (and are still being) made with through hole technology.

Experience tells me that many of these through hole circuit boards will need a plated hole repaired during its lifetime. Procedure 5.1 may be the one that will save your irreplaceable electronic assembly.

As good as this procedure is, there is one section that may cause even the most experienced repair technician some head scratching; it is how to select the right eyelet. I direct you to "eyelet selection criteria" section of the procedure.

The eyelet inside diameter should be 0.075 to 0.500 mm greater than the component lead diameter. (That is 0.003" to 0.020" for some of us.)

Eyelet press used to set eyelets for PTH repair.

The length under the flange of the eyelet should be 0.63 to 0.890 mm greater than the thickness of the Printed Circuit Board. (That is 0.025" to 0.035".)

The outside diameter ot the eyelet should allow the eyelet to be inserted into the drilled hole without force but should not exceed 0.125 mm (0.005") greater than the eyelet outside diameter.

Eyelet presses are available specifically for setting eyelets into circuit boards.

Several members of the Circuit Technology Center team contributed to this feature story.