Why do PCBs need to be panelized?


The purpose for panelization is mainly to meet production needs. Some PCB boards are too small to meet the requirements for making fixtures tester, so they need to be panelized together for production.

Panelizing can also improve the welding efficiency of SMT patches, such as completing the welding of multiple PCBs with just one SMT.

At the same time, it can also save costs, such as some irregularly shaped PCB boards. By splicing them together, waste can be reduced, thereby improving the utilization rate of the area.


Bad cases of no spacing panelization


Problem Description

Due to the screen printing of component packaging on the PCB board, which exceeded the board edge during design and was not inspected during assembly, there was interference with the components after seamless assembly, which affected SMT installation.


Problem Impact

Components beyond the edge of the board cannot be assembled without gaps, which affects the product development cycle. If forced assembly is carried out, such as half assembling and half not assembling adjacent components on the same side, it will also result in half of the product being scrapped.


Problem extension

Devices beyond the edge of the board, after being assembled without gaps, can still cause damage to the components and result in greater cost losses even if the plug-in is barely able to be inserted.

Applicable methods for PCB panelization

      1. CNC+V-CUT Panel

The method of adding V-cut to the gong board for assembly is suitable for boards with components on the board edge. It cannot be assembled without gaps. Instead, it adopts the form of processing edge for assembly, with V-CUT processing on both ends and a gap in the middle for easy welding of components. Otherwise, the components on the board edge interfere with each other and cannot be assembled and welded.

2. Stamp Hole Bridge Panel

Stamp holes are a bridging method of plate assembly. Stamp hole bridging can solve problems that cannot be solved by V-CUT bridging, such as circular plates, irregular plates, etc. If V-CUT is not possible, stamp hole connection can only be used for plate assembly.

3. V-CUT + Stamp Holes Bridge Panel

The V-CUT bridge assembly is suitable for regular boards, as the V-CUT knife cannot bend, so the position of the V-CUT must be a straight line in order to be V-CUT. It is also important to note that the position of the components near the board edge cannot be assembled with the V-CUT, otherwise it will affect assembly and welding.

4. No break-out rails Panel

In order to save the utilization rate of the board, small board assembly often does not process the edges. However, it should be noted that there should be no components at the edge of the V-CUT position. If the components are close to the edge of the board, it is best to leave a gap between the processing edges for assembly, otherwise it will also affect the assembly and solderability of the components.

What are high-density interconnect (HDI) boards?

HDI is the English abbreviation of high-density interconnect, that is high-density interconnect (HDI) boards, which is a circuit board with relatively high circuit distribution density using micro-blind and buried via technology.

High-density interconnect (HDI) boards are used more and more for some complex designs to reduce the space and thickness, communication industry and military aerospace products have too many boards that use high-density interconnect (HDI) technical to design, this will save too much money and time for their projects. Also, the most popular products such as IOT and smart wearable products all use high-density interconnect (HDI) boards, High-density interconnects (HDI) boards can make the PCB smaller to save space, the finish products will more cheap and portable.

The High-density interconnect (HDI) boards have inner layer and outer layers, and then use lasing drilling and fill copper process in the hole to realize the internal connection of each layer of lines. Generally, the build-up method is used for manufacturing. Ordinary High-density interconnects (HDI) boards are basically layered once, and high-end HDI uses two or more layers of layering technology, as well as advanced PCB technologies such as laser direct drilling, electroplating hole filling, and stacking holes.

Talos can produce high-density interconnect (HDI) boards with different stack up
Talos PCB normally use three types of stack up for high-density interconnect (HDI) boards, they will build up with high-density packages:

One-step high-density interconnect (HDI) board with only through holes and blind vias.
One-step high-density interconnect (HDI) board with PTH holes, Blind vias, and Buried Vias.
Two-step high-density interconnect (HDI) board Buildup with many microvias in more than two layers.
Stackup for high-density interconnect (HDI) boards
Following the IPC-2315 standard from the Institute of Printed Circuits (IPC), PCB manufacturers may use high-density interconnect (HDI) PCB stack up of types I, II, III, IV, V, or Vi. But the type IV, type V, and type VI are very expensive than normal cases.

The standard differentiates high-density interconnect (HDI) stack up with the use of vias, micro vias, blind vias, and buried vias, along with PTH holes, although the use of the lasing drilling is not strictly necessary for flex PCBs.

Type I stack up for High-density interconnect (HDI) board

High-density interconnects (HDI) PCBs of Type I stack up have a structure of a laminated core with at least one layer of micro vias on one or both of its sides. Type I High-density interconnect (HDI) may use PTH vias and blind vias, but without buried vias.

But there are 2 factors that limit the counts of layers in the laminated core of Type I HDI PCBs:

The max aspect ratio must be less than 10 to maintain reasonable reliability.
The thin FR-4 core may delaminate when used at high temperatures to do lead-free soldering.
So the Type I HDI stack up will not be significantly better than the normal large dense boards with multiple BGAs, because the PTH via pads will need to grow larger for higher layer counts. And the use of a single micro via layer does not offer appreciable benefits with the introduction of special features such as smaller diameter vias and thinner traces.

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Type II stack up for High-density interconnect (HDI) board
High-density interconnects (HDI) board Type III also uses micro-vias, blind vias, and buried vias, at least on two layers of microvias on one or both sides. LHD PCB and the other manufacturers can stagger microvias from other microvias, and stack them or stagger them relative to buried vias.

Though the High-density interconnect (HDI) board Type II stack up is significantly better than Type I for bigger dense boards using multiple fine pitch components, it has the same limitations as that of Type I in the context of the limitations on the counts of laminated core layers.

Because Type II High-density interconnects (HDI) PCBs can have micro-vias only on their outer layers, it is not very effective when there is only a single buildup layer for trace routing.

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Type III stack up for High-density interconnect (HDI) board
High-density interconnects (HDI) Type III structure construction also uses micro-vias, blind vias, and buried vias, with at least two layers of micro vias on one or both sides. LHD PCB and the other manufacturers may stagger micro vias from other micro-vias, and stack them or stagger them relative to buried vias.</p

Type III High-density interconnects (HDI) PCBs provide the best build-up for large dense multilayer PCBs using multiple large fine pitch BGAs, though they have the same limitations on the number of layers as faced by Type I and II when they use PTH holes and thin FR-4 cores.

Using micro vias in the inner layers of Type III High-density interconnect (HDI) PCBs allows the outer layers to be used for ground and/or power planes, leaving an adequate number of layers for signal routing. In addition, designers can obtain greater wiring density by stacking vias, but at a higher cost.

Designers can use different stack up to do the High-density interconnect (HDI) board, they can choose them based on the application and available budget. And Type III is the best and the most widely used in the PCB world. TALOS PCB can provide both Types I, II, and III for you, all base on your design and requirements for the High-density interconnect (HDI) board. Please feel free to drop your questions to us, TALOS PCB has a professional team to help you.