PCB Interposer Among New Hybrid Manufacturing Terms

A number of new terms are entering into today’s PCB discussions. Most of these terms involve those PCBs that continue to shrink, use smaller packaged devices, and have limited real estate. The term, “interposer” is among the newest ones joining such other new terms as PCB hybrid manufacturing, microelectronics, die attach, wire bonding, and others.

An interposer is a form of a new package or special substrate that serves as a “middle man” between components and the PCB. Another way to think about the PCB interposer is as a “technology bridge” connecting traditional SMT manufacturing with the newer microelectronics that greater numbers of OEM customers are demanding today. In effect, the interposer is an electrical interface connection between one socket to another.

The PCB interposer plays a vital role in the newly emerging hybrid manufacturing involving both SMT and microelectronics manufacturing that includes wire bonding.

Aside from the PCB interposer, die shear strength testing is yet another aspect of PCB hybrid manufacturing. Read more about it in one of our recent articles.

In the meantime, here are some tips on understanding die shear strength testing.

• A shear strength test is performed to check the integrity of the metallization between a die and the adhesive and the substrate.
• If the integrity is compromised when die shear force is applied, the die will pop up, disintegrate, or it will partially peel off.
• In effect, the die was not properly assembled on the substrate or PCB.
• The amount of force applied to verify die strength is directly proportional to die size.
• There are variances in different die shear strength testers. But each has a “push gate” and a die contact tool.
• Die shear strength testing is performed according to Mil Standard 883, Rev G or Rev F and test results must conform to it.

Caution must be exercised when an EMS Provider lacks not only the proper die shear strength test equipment, but also the expertise to correctly administer die attach. Without verification tools like this, the OEM is taking a gamble. The possibility exists, therefore, for a die in an OEM product to fall apart either in the lab or in the field, especially is the product is subjected to a rugged environment.