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HDI PCB : BACK TO BASICS

Release time: 14/10/2019

Ever since Charles Ducas has patented the revolutionary idea of forming an electrical path directly on an insulated surface, the electronic device manufacturers have stepped up their game in circuit board fabrication.  In the recent decade, the need for compact electronic devices also helped enhance their electronic engineering procedures. It has brought about the use of rigid flexible pcb (link to Rigid flex blog post ) . Later advancements made High-Density Interconnect (HDI) boards a great choice for  PCB manufacturing company.

However, fabricating such a circuit board requires some forms of understanding into the actual meaning and benefits of HDI PCB. Also, it’s crucial to know how consumer needs are shaping its relevance within the industry. PCB fabrication may also be impossible without gaining insights into the required materials for the board.

For a complete understanding of the circuit board, this article has made provision for relevant HDI PCB information by using the outline below as a guide.

  1. What is High-Density Interconnect PCB
  2. What are the benefits of HDI PCB?
  3. What is the relevance of HDI PCB in contemporary consumer needs ?
  4. What are the necessary materials for creating and laminating HDI Boards ?

1.   What is High-Density Interconnect PCB

High-Density Interconnect PCB otherwise known as HDI PCB is one of the fastest-growing PCBs technologies notable for higher circuitry density. It’s printed circuit board that has HDI rigid and flex layers interconnected for faster electrical signal transmission.

Other notable features of HDI interconnect include

  • Stacked and staggered microvias on all layers
  • Halogen-free base material (medium Tg) and polyimide
  • SMD population
  • Mechanical assembly in or on the housing

Typically, there are 6 various types of HDI printed circuit boards.  They include :

  1. Through vias from surface to surface
  2. With buried vias and through vias
  3. Two or more HDI layer with through vias
  4. A passive substrate with no electrical connection
  5. Coreless construction using layers pairs
  6. Alternate constructions of coreless construction using layer pairs.

2.   What are the benefits of HDI PCB?

There are lots of benefits associated with the use of HDI PCB. Aside from providing PCB manufacturers with the privilege of replacing multiples PCBs (which are interconnected with wires, ribbon cables and connectors )  with a single circuit board, HDI PCBs also help them reduce costs.

Other key benefits of HDI PCB include :

  • Performance optimization
  • Space optimization
  • Performance optimization

With HDI PCB, it’s possible to reduce an 8 layer through-hole PCB into a 4 layer HDI PCB.  Because the wiring capabilities of a well-designed HDI 4 layer PCB can achieve the same or better functions as that of a standard 8 layer PCB, there is a room for more performance. Additional layers in HDI PCB will boost the performance of an electronic device. Take, for instance, its pitch ensures there is more i/o in smaller geometries. Such features mean faster transmission of signals. Also , it indicates a reduction ins both signal loss and crossing delays.

  • Space optimization

The multiple via processes, via in pad and blind via technology all assist designers place components that are smaller closer together. Because the board allows an arrangement of smaller components, more space will be utilized for other functions.

The advantages Microvia HDI PCBs technology has over the traditional PCBs make it more popular over the traditional PCBs.  HDI PCB by laser drilling technology prevents the drawbacks people faces when using the traditional mechanical drilling technology.It also helps to prevent higher cost and improvement difficulties.

3.   What is the relevance of HDI PCB in contemporary consumer needs ?

The factors that drive the PCB Manufacturer demand for HDI PCB are needs for miniaturization of size and lower weight, high efficiency, and growing sales of consumer electronics.  The high adoption of HDI PCB manufacturing for numerous consumer electronics devices - laptops, smartphones, tablets and wearables, digital cameras proves that such a printed board is relevant for meeting contemporary consumer needs.

In 1992, the average cell phone has weight within a range of 220-250 grams. Unfortunately, it strictly for making phone calls. Through HDI PCB , people can now own smartphone weighing 151grams and performing many functions - texting, surfing the net, playing favorite songs or games, taking pictures and videos.

Since the late 20th century, video camera using cartridges the size of a novel has been evolving. Also, there are productions of camera that really fit into the palm of individuals hands.  HDI PCBs are proving to many consumers that bigger isn’t always better. Thus, their increased relevance in the consumer market.

  1. What are the necessary materials for creating and laminating HDI Boards ?

The fabrication of HDI PCBs requires the availability of some special pieces of equipment and adoption of processes like laser drills, plugging, laser direct imaging and also the sequential lamination cycles. It’s worthy to also note that the production of these kinds of the printed circuit board often requires much time.

The use of dry resin for lamination still adopt a heated roll method to apply the resist to the core material.  It’s is often advisable to preheat the material to a specific temperature in relation to the lamination process for HDI PCB. Such preheating process permit for a steady application of dry resist to the surface of the laminate. Consistent entrance and exit temperatures lead to less air entrapment beneath the film; this is critical to the reproduction of fine lines and spacing.

The resin-coated coppers were purposely created to enhance hole quality, drill times and also ensure a thinner PCB is achieved. Such copper is a low profile and thin copper foil fastened with the minuscule nodules to the surface.  It’s treated chemically and primed to allow the achievement of the finest line and spacing technology.

This advanced multilayer technology encourages designers to add more pair of layers one after the other to yield a multilayer PCB. By using a laser drill to create holes in the internal layer, there are chances for plating, imaging, and etching.

Via in Pad Process

The via in pad process gives room for vias to be placed within the surface with the flatlands. This via is plated, filled with epoxy, then capped and plated over and thus become virtually invisible.

Via Fill Types

There is a diverse kind of via fill materials. They range from non-conductive epoxy to copper filled, conductive epoxy, silver filled and even electrochemical plating. All these vias often result in a via that is buried within a flat land. They are soldered to become nomal land. 

Perhaps you need to further information about HDI rigid flex, don’t hesitate to contact Hemeixin at sales@hemeixinpcb.com . Do you need to know the market price for the product? Get quote here : http://pcbonline.hemeixinpcb.com/