Scrapes, Dings and Cavities Repaired

Figure 1: Badly broken board.

Millions are spent every year on the care and handling of circuit assemblies. Nevertheless, inevitably - and to the frustration of everyone involved - handling damage occurs. Boards, components, and assemblies are dropped, bumped, nicked and dinged with annoying regularity. Recently we were presented with a board severly cracked form edge to edge. (See Figure 1).  

One of the mighty international carriers ran over the box containing this board.  That's right, ran over, as in with a truck. 

Figure 2: Base board edge damage.

Believe it or not even that level of damage can be fixed, but frankly it's only occasionally worth the effort.  

When it comes to handling hiccups, far more common are the less traumatic impacts that cause less damage, but nonetheless make affected assemblies worthless. For example, take a look at the gouge in Figure 2.

Who knows how these things happen? Perhaps it's goes down like this, out on the floor there's a loud grind or bang and everyone within hearing distance runs to check on the safety of an operator. Once the operator's safety is assured, the product is assessed and if the stars are crossed a board or assembly is found damaged. Oh boy, what do you do now?

Figure 3: Precision grinder in use.

Well, let's take a look at the possibilities. Repair policy differs from company to company; some will repair anything they can, some allow no repair. Most companies have created some sort of repair and rework framework. Whenever considering repairs you're well advised to determine if your company policy specifically addresses your needs.

Many times repair is permitted, but the specifications for repair are not defined, or the type of repair is not even mentioned. That's where we can help.

Figure 4: Excess material removed.

In the case of the board in Figure 2 there is a set of instructions that can guide an experienced repair technician to bring the board back to an acceptable condition. Our web site contains a "Guidebook" with a variety of Base Board Repair Procedures. 

The steps listed here provide basic instructions for any type of minor board laminate repair. I hesitate to mention the hated subject of dental work, but what a dentist does to restore a tooth is a great (though painful) analogy for this type of work.  

Like a tooth with a cavity, the damaged area has residual material that must be removed in order to stabilize the future repair. To get rid of the bad stuff a precision grinding tool carefully, oh so carefully, grinds out the residual damage so as not to unnecessarily damage the base material or make the patient scream in agony. 

Figure 5: High-strength thermo-setting epoxy in-place.

See Figure 3. The result of this grinding should be a clean surface, tailor-made for attaching an epoxy repair. This is also when the patient finally relaxes in the chair, relieved of the nagging fear that the dental witch doctor is not going to drive a ball mill into the roof of his mouth. See Figure 4.

Once the area is prepared and cleaned, epoxy is added - just like the filling material for a tooth. See Figure 5.

Lastly the filling epoxy is shaped and colored in order to ensure the repair matches the original base material as closely as possible. See Figure 6.

Figure 6: Finished base board repair.

Voila! Base board damage is never a good thing, but if it happens it doesn't necessarily mean all is lost. When your in a bind give us a call. Perhaps we can work a little magic and put that board back in play.

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