The world of electronics has reached a new dimension in terms of preciseness. That is now occurring in PCB microelectronics manufacturing with the onset of infinitesimal measurement and calibration of a variety of assembly tasks associated with PCB microelectronics.
Recall from our earlier writings that PCB microelectronics manufacturing is a companion to traditional SMT manufacturing, now forming PCB hybrid manufacturing to deal with a growing number of advanced products.
The new dimension of preciseness for PCB microelectronics assembly and manufacturing is delivered by a new breed of high-powered laser microscopes, Fig. 1. These are the tools that perform highly effective inspection and calibration. They give you assurances that substrates and dies are intact during incoming inspection, as well as post-assembly verification. Plus, they are precisely calculating measurements. They are also taking highly accurate readings for a specific height, length and width of wire bond loops and curvatures to make sure specifications are met, as defined in the scope of work.
For more details, check out our article in SMT007 Magazine. In the meantime, here are some tips that’ll help you get started learning more about this area.
- Inspection includes die, epoxy resin and solder mask bleeding and air bridge.
- Die surfaces are inspected for defects like fine cracks, corner chipping or corrosion, contamination or oxidation.
- Epoxy under the die is inspected to check the amount deposited. Misjudging that amount can lead to a “floating die,” which is not desirable.
- Solder mask may bleed onto the wire bonding pad. The pad’s surface may not be sufficient in size to perform the bonding. The scope inspects and verifies this issue doesn’t exist.
- Residues from SMT manufacturing are inspected. If residues remain, the surface needs to be cleaned.
- Understand that an air bridge is the air distance created to bypass a component located between two other components. That’s done to connect a wire bond from one point to another and overpassing the middle component.
It is absolutely essential to calculate intricate fine wire bond loops and curvatures for some projects. For example, a 3D profile is created for a wire bond loop’s 5 µm accuracy in measuring the height. In this 3D profile, various aspects can be viewed at regular and tilted angles to give between viewing pictures. Those include a die and epoxy thickness and distance between the substrate or interposer and die. Creating this 3D profile gives a very clear-cut picture, which can easily be precisely measured. It also provides a very good visual, which is used as a proof of effective versus poor microelectronics assembly.