FAQ about printed circuit boards

Below we have listed some of the most common questions we receive and everyday discussion topics. You can also ask your PCB question here.


What is a microvia?

According to the new definition within IPC-T-50M a microvia is a blind structure with a maximum aspect ratio of 1:1, terminating on a target land with a total depth of no more than 0.25mm measured from the structure’s capture land foil to the target land.

What is meant by a blind via hole?

It is a hole that runs from an outer layer to the inner layer, but not through the entire PCB. These holes can be drilled mechanically or using laser technology. The image shows a laser drilled blind via.

What is meant by a buried via hole?

This is a hole that runs between one or more inner layers. They are normally mechanically drilled.

What type of via hole plugging is recommended?

The preferred type of plugging for standard product (not including capped via hole) is IPC 4761 type VI filled and covered, with target being complete fill. The image below shows type VI with liquid soldermask coverage.

Single sided plugging is not recommended (including type II tented and covered) due to concerns over entrapment of chemistry or likelihood of solderballs being present with HASL finishes (LF and SnPb).


Do I have to use an FR4 material with a high Tg (Tg = glass transition temperature) for lead-free soldering?

No, not necessarily. There are many factors to be taken into account, e.g. how many layers, the thickness of the PCB and also a good understanding of the assembly process (number of soldering cycles, time above 260 degrees, etc.). Some research has shown that a material with a “standard” Tg value has even performed better than some materials with a higher Tg value. Note that even with “leaded” soldering the Tg value is exceeded.
What is of most importance is how the material behaves at temperatures above the Tg value (post Tg) so knowing the temperature profiles the board will be subjected to will help you look evaluate the necessary performance characteristics.

Which PCB surface is best for lead-free soldering?

There is no “best surface;” all surfaces have their pros and cons. Which one you should choose depends on many factors. Please consult our technicians or review the information on surface finishes within this section of the website.

How many reflow cycles can FR4 materials withstand?

It is hard to give a precise answer, but we have made tests with material with up to 22 reflows, four of these with a peak temperature of 270C°. The stress after 22 reflows is considerable and material can degrade, but all connections remained functional. Our recommendation is to choose a higher grade material where there are more than 6 layers and thicker than 1.6 mm.

FAQ about Multilayer PCBs

What is a multilayer PCB?

A multilayer PCB is a printed circuit board that consists of multiple layers of conductive material sandwiched between insulating layers. This type of PCB is used for complex electronic circuits that require more space for routing and component placement.

How does a multilayer PCB differ from a single-layer PCB?

A single-layer PCB only has one layer of conductive material, while a multilayer PCB has multiple layers of conductive material. The multiple layers in a multilayer PCB allow for more space for routing and component placement, making it possible to create more complex circuits.

What are the advantages of using a multilayer PCB?

Some of the benefits of using a multilayer PCB include increased circuit density, improved performance, reduced electromagnetic interference, and reduced circuit size.

What materials are used in the construction of a multilayer PCB?

The materials used in a multilayer PCB typically include a substrate material, conductive layers (such as copper), insulating layers (such as polyimide or FR4).

How are multilayer PCBs manufactured?

Multilayer PCBs are typically manufactured using a process that involves layering, drilling, etching, and laminating. The process starts with the creation of a substrate, followed by the deposition of conductive layers and insulating layers. The layers are then drilled to create vias and holes for component placement. Finally, the board is laminated to ensure stability and durability.

FAQ about HDI PCBs

What is a HDI PCB?

IPC-2226 defines HDI as a printed circuit board with a higher wiring density per unit area than conventional printed circuit boards (PCB). They have finer lines and spaces ≤ 100 µm / 0.10 mm, smaller vias (<150 µm) and capture pads <400 µm / 0.40 mm, and higher connection pad density (>20 pads/cm2) than employed in conventional PCB technology.

Why should I turn to HDI PCBs?

At some level of circuit complexity, turning to an architecture with blind and buried vias will result in better yield and lower cost than would a through-hole design.

How does HDI PCBs keep my cost down?

HDI PCBs help reduce costs by decreasing size, minimizing the number of components, reducing signal interference, and automating the manufacturing process.

How do I select materials for HDI?

Materials play a large role in terms of manufacturability and direct cost of your circuit board. Here is a tip: The goal is always to select the right material for manufacturability that, at the same time, meets your temperature, and your electrical requirements. When it comes to materials, make sure that your high-speed material is also suitable for your HDI design. They are many other factors that come into play when selecting the proper materials for your design. View more.

What is the laser drill accuracy?

It is very safe to assume it is +/- 1 mil accuracy. Usually, in a staggered microvia formation, the diameters of both operate and lower microvias are the same. The key parameter that decides whether the staggering is possible or not, without the lower microvia needing to be filled, is the dimension E, the vertical separation between the central access of the two microvias. For staggering to be viable, the value of E must be greater than the microvia diameter.

FAQ about Double sided PCBs

What is a double sided PCB?

Double sided PCB, also known as double sided printed circuit board, is a type of circuit board that has conductive pathways and components on both sides of the board.

What are the advantages of double sided PCBs?

Double sided PCBs offer several advantages including increased component density, improved signal integrity, and reduced size and weight of the final product.

What is the process of manufacturing double sided PCBs?

The process of manufacturing double sided PCBs main involves drilling, plating, etching, lamination, and testing etc.

How does the trace routing differ in double sided PCBs compared to single sided PCBs?

In double sided PCBs, trace routing can be done on both sides of the board, allowing for a more flexible and efficient design. In single sided PCBs, trace routing is limited to one side only.


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