Challenges of electronics manufacturing - component sizes
From the trend towards miniaturization of components to the increasing complexity of printed circuit boards and the increased placement density on assemblies - electronics manufacturers today face a number of challenges that affect our daily work.
In the "Challenges of electronics manufacturing" series, we look at various trends and developments that will concern us as an EMS service provider today and in the coming years. In the first part, we take a look at the development of component sizes. Opposing trends demand a high degree of skill, precision and flexibility from our manufacturing processes.
Challenge 1: Miniaturization of passive components
You might think that the topic of miniaturization is an old hat. But for us in electronics production, the constant miniaturization of components is pushing the boundaries of what is feasible. For some time now, development has been moving from macroscopic components that can be assembled by hand to microscopic components that are barely larger than a human hair. These components challenge us every day in our work and also in technology. In short, technological progress is constantly setting new standards for precision and production techniques for electronics manufacturers.
Components such as resistors or capacitors are essential for an electronic assembly, but need their space on the circuit board. In order to keep this space as small as possible, miniaturization is constantly increasing. For a long time, shape 01005 was the smallest component on the market at 0.4 x 0.2 mm. This already made it difficult for many SMD assembly machines to pick up the components correctly and place them on the board. But it can be even smaller - the smallest component 008004 currently measures just 0.25 x 0.125 mm and is therefore only almost half the size of component 01005.
| Component shape | Metric in mm |
| 01005 | 0.4 mm x 0.2 mm |
| 009005 | 0.3 mm x 0.15 mm |
| 008004 | 0.25 mm x 0.125 mm |
This shrinkage is an impressive technological achievement, but also poses increasing challenges for manufacturing processes. How can a machine grip or pick up the component? And how can it be ensured that this component is actually placed on the PCB if it is barely visible to the naked eye? The precise placement and soldering of these tiny components on PCBs requires state-of-the-art technologies.
Challenge 2: Increasing the size of SMD connectors
Contrary to the development of components such as resistors and capacitors, a different trend applies to SMD connectors: where previously several small connectors were placed on the PCBs, today fewer but larger connectors are used to bundle the signals. Some of the connectors have more than 250 pins to transmit signals.
An SMD connector is used to connect or disconnect electrical wires. In contrast to discrete components such as resistors or capacitors, SMD connectors are components that have been developed to establish an electrical connection between several assemblies or devices. They are soldered directly onto the circuit board and have pins or connections that transmit signals, power or data between the connected components in a space-saving manner.
To save additional space, the pins of many connectors are no longer facing outwards, but inwards, directly under the body. The assembly process is therefore to a certain extent blind, as only the outer edges of the pins are visible. The challenge in production is that the assemblies must be processed extremely cleanly to prevent bridging between the pins. This is because bridging is almost impossible to correct, especially with pins that are located under the connector. With pin spacings that are sometimes smaller than 0.4 mm, the limits of manual soldering capabilities are also reached.
Excursus - What actually is a solder bridge?
A bridge between solder joints (e.g. pins of connectors) can occur if the components are not placed correctly or if too much solder/paste is applied to the PCB. During the soldering process, the solder creates a connection between the individual connections, which can lead to malfunctions on the assembly. To prevent such bridging, it is necessary to dose the solder paste precisely, adjust the soldering temperature carefully and place the components correctly on the PCB.
Challenge 3: Focus on active components - from BGAs to VFBGAs
So far, we have been talking about passive components. Active components are also affected by the trend towards miniaturization. A classic design of active components is a BGA - Ball Grid Array. In contrast to other components with side connections, the connections of a BGA are located directly under the component in the form of solder balls. These balls usually have spacings of 0.7 mm to 2.5 mm.
In order to increase the packing density on the assemblies, the BGAs are becoming smaller - they are becoming VFBGAs (Very Fine Ball Grid Arrays). The name says it all: VFBGAs are characterized by even smaller distances between the solder balls. Less than 0.5 mm spacing is now the standard. A single component can contain several hundred of these solder balls.
As with connectors, very precise printing of solder paste is required before assembly. This is because solder bridges between the balls are almost impossible to correct. Instead, in the event of bridging, the entire BGA must be removed and the component repositioned. The integration of VFBGAs in electronics production therefore requires extremely precise work and a high-quality production environment.
The solution: precision and quality control in production
Some components are getting smaller and smaller, others are getting bigger and bigger. As manufacturers, we often ask ourselves: How can we process these small, very fine component structures cleanly without causing short circuits? Every electronics manufacturer has to face this challenge today and adapt their production processes accordingly. In order to provide our customers with the best possible results, regular tools must be replaced by specialized systems - especially when it comes to automated PCB assembly.
Print stencils with electropolishing and an additional nano-coating, for example, ensure clean paste printing. Electropolishing in combination with nanocoating improves the contour sharpness of the solder paste and also prevents the paste from sticking to the underside of the SMD stencil thanks to the non-stick effect. This means that even the finest structures can be printed cleanly, stably and reliably.
In the next production step, however, the placement machines themselves must also be able to pick up and place the small components. SMD machines, for example, must have the appropriate material feeders to pick up both very small and very large components. The same applies to grippers or nozzles in the placement machine. Not all SMD lines are equipped with the appropriate tools as standard to be able to cover both extremes of components.
Narrow, tubular suction cups that look like pipettes are installed in the pick-and-place machine. The suction cups remove small SMD components from material rolls of a feeder and place them on the assembly. These small suction cups are called "nozzles". Grippers are not suitable for these small SMD components.
Grippers are used to pick up larger components such as connectors or other components that cannot be picked up by a suction cup from the feeder rollers and position them precisely on the PCB.
From optical inspection to X-ray inspection
As an electronics manufacturer, flawless assembly is our top priority. However, in the continuation of the assembly process, the challenge that regular optical inspections cannot detect all sources of error is becoming increasingly apparent due to the small designs. Regular AOIs (Automatic Optical Inspection) reach their limits. On the one hand, even a 3D AOI cannot detect defects in connections that are located under the component, as is the case with BGAs. Secondly, the programming of AOIs must be extremely careful in order to monitor even the smallest pin spacing without permanent pseudo defects. This is why the trend is towards X-ray-based inspection devices. These make it possible to check the quality of the soldering underneath the component and ensure that all components are correctly positioned. AXIs (Automatic X-ray Inspections) are becoming increasingly relevant to ensure complete and reliable quality control.
At A+B Electronic, we always keep an eye on trends, challenges and solutions in the electronics industry. This is how we ensure that our customers' projects are produced in a future-proof manner. Do you have questions about a project? Then please contact us. Together we will find the best solution.
