Reliable Quality Assurance of Printed Circuit Boards
Optiprint supplies highly advanced printed circuit boards for many industries, such as automotive, sensor, space engineering, and medical engineering. When the company was exploring the market for a non-contact, areal surface measurement system, Alicona’s 3D measurement systems caught its attention.
Optiprint now depends on Alicona’s InfiniteFocusSL in the quality assurance guarantee of printed circuit boards. Alicona’s solution now enables Optiprint to measure the roughness and form of complicated, small-sized component surfaces with only a single system.
At present, printed circuit boards act as carriers for simple to very complex electronics. For three decades now, Optiprint, located in Berneck, Switzerland, has been manufacturing highly advanced circuit board solutions. Latest high-performance materials and better efficient ways of assembly, like the Chip-on- Board technology, are turning out to be highly relevant. Due to these challenges, Optiprint required a suitable system for flatness measurement and areal topography of chip pockets.
Alicona’s 3D measurement system have allowed us to optimize our processes significantly and take major steps in securing the quality leadership of our products.
Simon Hütter, Quality Manager, Optiprint
Alicona’s 3D measurement solutions have enabled Optiprint’s customers to achieve error-free wire bonding and chip bonding. Figure 1 shows area-based roughness measurement of the microvia.
Figure 1. Area-based roughness measurement of the microvia to find traces of powder.
Microvias: Optical 3D Measurement of Diameter and Depth
Optiprint’s quality assurance aims to supply printed circuit boards that are apt for additional processing by customers. In order to guarantee good electrical connection of multi-layered circuit boards, it is important that the microvias are drilled based on pre-defined diameter and depth parameters. The measurement systems from Alicona enable Optiprint to validate the height and diameter step of the microvias to ensure that the correct layers have been connected.
Another measurement method for laser-dilled microvias is to discover traces of powder. When molten material lumps together, traces of powder are formed at the outer edge of laser drill holes. With improved laser parameters for different materials, these bulges are reduced. In order to detect the bulges, the planarity at the transition of the surface to the microvia is performed by making roughness measurements by Alicona systems.
Except for the measurements of diameter, depth, and planarity mentioned above, microvia bottoms also have to be tested during quality assurance. Here, the most important error to check is residual insulating material, as this can obstruct the electrical conductivity of the total circuit board. It is crucial to validate that this area of the microvia is clean prior to further processing. Optiprint achieves this with Alicona’s high-resolution true-color 3D visualization systems. Figure 2 shows 3D visualization of the chip pocket before surface finish, and Figure 3 depicts a 3D measurement of shape.
Figure 2. 3D visualization of the chip pocket before surface finish. The visualization has assisted to enhance the Chip-on-Board technology. Optiprint has managed to gain a better understanding of the interaction between assembly process and surface properties.
Figure 3. 3D measurement of shape a co-planarity of contact pads to ensure perfect conditions for wire bonding.
As the subsequent stage of the manufacturing process, chip pockets are milled into the circuit board to make space for the chips which the end customer will later connect to the circuit board. Chip-on-Board technology is also referred to connecting the chips to the milled pockets. In order for the silicium chips to stay securely in place, the milled pockets must be flat and should have proper shape. Using Alicona’s roughness measurement system, Optiprint was able to gain a better understanding of the interaction between assembly process and surface properties which ultimately resulted in a better manufacturing process. In order to guarantee good surface quality and, subsequently, error-free attaching, Optiprint determines flatness, shape as well as height steps of the chip pockets.
“Only when we started using areal roughness measurement was it that we mastered the process for milled pockets”, states Simon Hütter.
3D Profile Form Measurement of Bondpads
Electrical bonding of the Chips on Board is another stage in the manufacturing method. The chips’ electrical interconnecting with the circuit board using bond wires is also known as wire bonding. Bondpads has to be error free from issues like dirt and roughness, as these reduce the strength of the bond interconnection. 3D profile measurement system from Alicona facilitates Optiprint to validate the co-planarity and form of contact pads on the printed circuit board and assure perfect conditions for wire bonding.
Our customers use printed circuit boards by Optiprint to manufacture products of the highest quality. Alicona‘s customized 3D measurement solutions play a key role in enabling us to provide our customers with the exceptional quality they need. Their systems contribute significantly to our company‘s success. We can only recommend Alicona to everyone.
Simon Hütter, Quality Manager, Optiprint
The below mentioned parameters of multi-layer circuit boards can be determined and documented accurately using Alicona’s 3D measurement systems:
- 3D profile form of bondpads
- Areal roughness at the transition of surface to drill hole
- Rating and analysis of quality characteristics
- Areal roughness and flatness at the bottom of microvias
- Diameter and depth of microvias
- Areal roughness and topography of milled pockets (chip pockets)
This information has been sourced, reviewed and adapted from materials provided by Alicona Imaging GmbH.
For more information on this source, please visit Alicona Imaging GmbH.