Surgeon grade rework and repair, by the book and guaranteed.®
Newsletter | Contact Us
Phone: 978-374-5000
How To Restore Missing Internal Layer Connections More Features
How To Restore Missing Internal Layer Connections
Figure 1. Exposed inner layer.
Several multilayer backplanes were mistakenly manufactured with missing plating for 24 holes on each board. The top and bottom side pads were in place, but the holes had no plating thus the inner layers we not connected. See Figure 1.

Each of the holes required an internal connection to either layer 2 or layer 3. Making connections to various layers complicated the rework solution and of course these backplanes were critical so a reliable rework method was required ASAP.

How To Restore Missing Internal Layer Connections
Figure 2. Copper ribbon soldered to exposed inner layer.
Due to ground shielding on the bottom side of the backplane, all rework needed to be completed from the top side. Figure 1 shows the top side of board showing some of the locations requiring rework to establish missing internal connections.

After consultation with our engineers, our rework operators, and the customer, it was decided that the best rework approach would be as follows.
  1. Use a Precision Drill system, fitted with a stereo microscope and an 0.080" carbide steel end mill and carefully machine down to the respective internal layer and expose the copper signal trace. See figure 1.
  2. How To Restore Missing Internal Layer Connections
    Figure 3. Connections completed and areas filled with epoxy.
    Select a length of 2 oz. pure copper ribbon that matched the width of the signal trace.
  3. Tin the copper ribbon and the exposed inner layer with solder.
  4. Solder the copper ribbon from the exposed internal layer to the top side surface pad and electrically test to confirm the connection. See Figure 2.
  5. Complete the rework by filling each milled hole using color-matched high-strength 2 part epoxy and cure as required. See figure 3.
Several members of the Circuit Technology Center team contributed to this feature story.

Related Guide Procedures

4.2.1 Conductor Repair, Foil Jumper, Epoxy Method
Procedure to repair damaged conductors and circuits.
4.2.5 Conductor Repair, Through Board Wire Method
Procedure to repair damaged conductors and circuits.
4.2.6 Conductor Repair, Inner Layer Method
Procedure to repair damaged conductors and circuits.
4.2.7 Conductor Repair, Surface Plane, Film Adhesive Method
Procedure to repair damaged conductors and circuits.

Related Products

201-3130 Circuit Track Kit
Kit to repair circuit board damage including lands and conductors.
201-2100 Professional Repair Kit
Kit to repair circuit board damage including pads, lands, conductors, base material and plated holes.

Related Feature Articles

Case of the Missing SMT Pads
Everyone loves a good mystery, unless, of course, that mystery has to do with something important that's missing from your valuable circuit ...
Isolating a Plated Hole From Ground
Once involved in rework and repair, you quickly realize that all the tools you need to get the job done are just not always available ...
Conductor Repair - When Appearance Counts
Repairing a damaged circuit with a wire is commonplace, but the repair will shout out "Look at me, I've been repaired!." When you want ...
Rework for Pad and Component Mismatch
It's a wonder pad to part size mismatch doesn't happen more often, considering the thousands and thousands of opportunities on ...
Adding A Via Hole
We've all heard of via in pad, blind vias, even buried vias, but have you ever experienced the "Via to nowhere" phenomena? Well, here's ...
Inner Layer Conductor Modification
Feature covers need to restore a ground plane that should have served as a return path for signals between plated through holes in ...
Questions / Comments?
Call 978-374-5000 or submit your questions, comments and requests using the form below.

Your Name

Your E-mail

Your Phone

Your Company

Your Country

Send us a file

Maximum file size 4 megabytes.


Customer Comments
"We were struggling with BGA rework on four of our most complicated assemblies until we decided to send them to you. Your team has been awesome and you've come through on every project."
R.R. Oklahoma City, OK USA
Stop PCB Scrap Today
Stop PCB Scrap Today
What happens to your valuable circuit boards when they're damaged? Can they be repaired reliably and cost-effectively? Yes, if you have the skills and knowhow.
Learn more ...
Six Fast Fixes for Circuit Boards
Six Fast Fixes for Circuit Boards
Use this versatile kit to fix damaged SMT pads, lands, gold edge contacts, conductors, plated holes and base board. It's the total package.
Learn more ...
6 Common Mistakes of BGA Rework
6 Common Mistakes of BGA Rework
BGA rework is a very challenging procedure. Doing it right depends in large part on the skills and knowledge of the rework technician.
Learn more ...
Circuitry Repair on Multilayer PCBs
Circuitry Repair on Multilayer PCBs
Learn about services to repair severe damage to conductors and plated holes, including damaged holes in multilayer PCBs.
Learn more ...
About Us | Base Board Repair | BGA Reballing | BGA Rework | Coating/Marking | Circuit Repair | Component Salvage | Conflict Minerals | Contact Us | Copyright/Disclaimer | Directions | ECO/Modification | Feature Articles | Frequent Questions | Gold Contacts | Inspection | Order Tracking | Newsletter | Plated Hole Repair | Prices, Terms, Delivery | Products | Privacy | REACH | RoHS | Services | SMT/BGA Repair | SMT/PTH Rework | Sitemap

Circuit Technology Center, Inc.
22 Parkridge Road
Haverhill, MA 01835 USA
Copyright © Circuit Technology Center, Inc.. All rights reserved.