5.2 Plated Hole Repair, Double Wall Method
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This procedure covers the use of an eyelet for the repair
of a damaged land on a hole that has an inner layer
connect.
Caution
This method is used to restore the integrity of a through
connection on a multilayer circuit board, having an
inner layer connect, but ONLY if the full barrel of
the plated through hole remains intact. If there is
barrel damage see appropriate procedure.
Caution
This method will reduce the inside diameter of the hole.
The minimum hole size requirement must be checked for
acceptance.
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Damaged Plated Hole with
Inner Layer Connection |
Tools and Materials
Ball Mills
Caliper
Eyelet
Press
Eyelets, Various
Sizes
Flux, Liquid
Knife
Micro-Drill
System
Microscope
Pin Gauges
Plated Hole
Repair Kit
Setting
Form Tool, Various Sizes
Setting
Anvil, Various Sizes
Solder Iron
Solder
Wipes
EYELET SELECTION CRITERIA
ID - Inside Diameter
The eyelet inside diameter should be a .075 - .500 mm (.003"-.020")
greater than the component lead diameter
LUF - Length Under Flange
The length of the eyelet barrel under the flange should be .630
- .890 mm (.025" - 035") greater than the thickness of the circuit
board. This added length allows for proper protrusion when setting
the eyelet.
FD - Flange Diameter
The eyelet flange diameter should be small enough to prevent
interference with adjacent lands or circuits.
OD - Outside Diameter
The clearance hole drilled through the circuit board should
allow the eyelet to be inserted without force but should not
exceed .125 mm (.005") greater than the eyelet outside diameter.
Procedure 5.2 Plated Hole Repair, Double
Wall Method
Figure 1: Insert eyelet into the hole.
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| 1. |
Clean the area.
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| 2. |
Examine the hole to ensure that there is no
damage to the wall of the hole. Check continuity
to establish the integrity of the connection.
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| 3. |
Select an eyelet using the Eyelet Selection
Criteria. Use a pin gauge and caliper to measure
the existing plated hole dimensions. The eyelet
must have an inside diameter sufficient to receive
the component lead and an outside diameter that
will allow the eyelet to be inserted into the
hole without force.
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| 4. |
Remove oxides from the surface lands where the
eyelet is to be installed using a buffer and
clean.
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| 5. |
Apply a small amount of liquid flux to the land
or circuit on the circuit board surface, if
any, and tin with solder using a soldering iron
and solder. Clean the area.
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| 6. |
Insert the eyelet into the hole. If a new circuit
is required, the new circuit may extend into
the hole and the flange of the eyelet will secure
the new circuit in place. (See Figure 1).
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Figure 2: Set the eyelet using an
Eyelet Press.
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| 7.
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Select the proper setting tools and insert them
into the eyelet press. (See Figure 2).
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| 8. |
Turn the circuit board over and
rest the eyelet flange on the lower setting tool. |
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| 9. |
Apply firm even pressure to form
the eyelet barrel. |
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| 10. |
Apply a small amount of liquid flux and solder
the eyelet flanges to the lands on the circuit
board surface if necessary. Clean the area.
Inspect for good solder flow and wetting around
the eyelet flanges and lands.
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| 11. |
Clean the area. |
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| 12. |
Install the component lead and
solder, if required. |
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Figure 3: Completed repair.
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Evaluation |
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| 1.
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Visual examination, dimensional
requirement of land diameter and inside diameter. |
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| 2. |
Electrical continuity measurement. |
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