Why Via Hole Filling? Why now?

Why should we invest in this technology?

  • In the last 20 years the via hole filling process was clearly the driver for the PCB board development and new designs.
  • The hole filling process allows the board designer to save valuable space on the board and create a higher board count per panel by using the same amount of material, chemistry and energy.
  • The percentage of panels with filled holes is steadily growing. Some companies who failed to see the future are no longer in business.

What is the right timing for the investment?

  • The first investments in hole filling equipment started nearly ten years ago. We are proud to be one of the first companies which started with equipment sales and service for this technology.
  • The hole filling process also effected and related to other processes during the PCB board production. It is not a ‘switch on’ process. Even the best equipment on the market needs some time to get the best quality out of this process. The operators need to get some experience and a feeling for setting up the right parameters for different panel designs.
  • Since other processes can also be affected by the hole filling process, some new process guides will need to be worked out.
  • It is important to have such a system in house and up and running before the orders come in. To start such a process with the pressure of an immediate quality guarantee is not a good decision.

Picture7How has this technology developed over the last years, what is the developing direction?

  • The hole filling process started out from a simple safety filing requirement. Put epoxy in the holes so that there is no other unknown chemistry. Then it moved from mainly semi conductive filling with plating over the holes to nonconductive fillings with plating over the holes. Space saving again was the driver for this technology.
  • The developing direction was in the same time from lower technology level with low aspect ratio to high aspect ratio holes. In the same time the hole diameter comes down from about 0.4mm to 0.1mm on through holes. In the beginning the majority of customers used the screen printing method for the hole filling. Because there is a limit on hole size and aspect ratio for the screen printing the industry moved forward with special hole filling equipment which is able to break the screen printing limits.
  • The next level is the filling of blind holes, which puts another development pressure on the equipment manufacturer. The equipment developed and used for filling through holes was able to fill also blind holes up to a certain percentage. Trapped air inside blinds is most likely to be found in vacuum chamber machines. In order to make blind hole filling a safe and reliable process, a total new type of filling method was necessary to develop.
  • This development even goes further with the demand of many customers to fill blind holes on both sides and through holes in one step.
  • Conductive paste. The new driver for further development is the ‘real conductive filling’ without plating. We have adjusted our filling head system to meet this demand because of the high costs of the paste. Right now, companies like Tatsuta offers paste for the non plating process. With more and more customers joining this technology the price for the paste will make this process much more attractive for their customers. But again, one of the most important points for this process is reliable filling which can only be done by a ,high vacuum system’, like our newly patented filling system on the THP35.

Picture6What machine capability will we need for an investment into future needs?

A machine which will also fit in future needs should be able to:

  • to fill through holes with all aspect ratios which can be drilled
  • the system must be able to fill blind holes reliably without trapped air
  • through holes and blind holes have to be filled at the same time
  • no limits on the paste if it is conductive or nonconductive
  • the machine programming system must be able to store all parameter dates for later quality tracking

Do we have alternatives to avoid this investment?

  • One alternative is to go with screen printing which will limit the capability and process quality. There is a big risk of loosing customers looking for more advanced work.
  • For filling blind holes, plating can be used, but there is a limit of aspect ratio.

Newer designs are skipping up to three layers with depth controlled drilling. These designs are already over the boarder line for plating filling. High vacuum filling systems are able to fill these designs. The development will go even further to more skipped layers in order to save more space on future boards.

If we look at our customer base over the last 5 years, we see that companies which have made the investment in the hole filling process even in these though times, are still in operation and some of them are very busy. Others which have decided against the investment have vanished from the marked during the last year. This doesn’t mean an investment in the hole filling process will save a company, but an investment in the right time will certainly improve the company’s capability and lower the risk of loosing new orders.

Kind regards,

Erwin Haertl
President ITC