Ladle on Manufacturing: VCP—The Future of Plating

Electroplating copper has been a standard part of the PCB manufacturing process for more than 50 years. The basic technology has not changed very much in that time. Normal arrangements involve a series of chemical and rinse tanks into which panels are dipped first to clean the copper surface and then to electroplate copper onto the surface and through the drilled holes and vias.

Some smaller manufacturers still use a manual process where an operator moves the panel(s) being plated from tank to tank to complete the process. Larger manufacturers use machines that may have a very similar arrangement of tanks but on a larger scale, and an automatically controlled transporter moves the panels.

The normal process options for the plating operation are either panel or pattern plating. Either way, the panels are prepared by drilling all of the holes required and then making a thin conductive deposit such as electroless copper or carbon/graphite. This will be used as the base for electroplating through the holes. If you panel plate, the whole of the surface is electroplated as well as the drilled holes. If you pattern plate, then a plating resist is used to make an image on the surface, and the copper is electroplated selectively.

Over the years, developments have been made from time to time that have helped to refine the process. For instance, floating shields within the copper tanks have helped to deal with panels of different lengths. Pulse rectification has enabled high aspect ratio panels to be produced with an even deposit of copper through the holes. However, if you had run one of the original processes back in the day, you would still recognise a more modern version of the process.

Even with the best available traditional plating line, there are still some shortcomings that are difficult to overcome. It is not efficient to plate panels one at a time—you would need a lot of plating tanks, and throughput would be pretty low. Most machines are based on plating several panels at a time either using a jig to hold them in position or hanging them from top clamps in a long row. In both methods, each panel has a slightly different plating effect, and therefore, a different copper thickness.

This variation in copper thickness means that circuit performance is compromised. The target should always be for each circuit produced to be exactly the same.

The vertical continuous plating (VCP) process offers a good solution to this problem of variation. Instead of dipping panels in a succession of tanks, the VCP process moves the panel in a linear motion through the critical process stages. In the case of the copper tank, this means that the panel is moved through a very long plating tank from one end to the other, and every panel in the batch has exactly the same process path; thus, the variation from panel to panel is absolutely minimal.

This article originally appeared in the January 2019 issue of PCB007 Magazine, click here.

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2019

Ladle on Manufacturing: VCP—The Future of Plating

03-19-2019

Electroplating copper has been a standard part of the PCB manufacturing process for more than 50 years. The basic technology has not changed very much in that time. Normal arrangements involve a series of chemical and rinse tanks into which panels are dipped first to clean the copper surface and then to electroplate copper onto the surface and through the drilled holes and vias.

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2018

Developments in Wet Processing: Beyond Spraying and Dipping

07-27-2018

Spraying and dipping! Wet processing is based on two simple principles: Spray the work piece or immerse it in a bath. Most of the things you do in a complex machine you could also do with a series of buckets, but the results are likely to be much less reliable or efficient.

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Ladle on Manufacturing: What’s New?

04-27-2018

When it comes to PCB processing, it is not often that you are able to come up with something completely new. There may be some notable exceptions, but often a new process is more honestly an adaptation of a similar process, perhaps from another industry segment or a different application.

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Failure Analysis: A Critical Component to Process Engineering

01-31-2018

My definition of process engineering: attempting to put together the perfect manufacturing stages to produce the desired product. Printed circuit production includes many diverse production stages requiring a wide range of skills and knowledge to manufacture the perfect product.

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2017

Ladle on Manufacturing: Fabricating for Signal Integrity

11-01-2017

Signal integrity! In a world which is increasingly high-speed and digital, the chemical-dependent and mainly analogue-controlled world of PCB manufacturing is not always a comfortable partner.

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Ladle on Manufacturing: Back to Basics

09-19-2017

Many companies in the printed circuit industry are based in a single factory. When everything is going well, this can really help to get the best out of people and machinery. The main drawback is that seeing the same issues day after day, it can be easy to accept your manufacturing problems as being normal.

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Ladle on Manufacturing: Why is the Developer Missing at BATM Systems’ Romania Facility?

08-21-2017

I recently had the great pleasure to be working with BATM Systems at their new factory in Romania. The process concept is the brainchild of Steve Driver. For those who don’t know Steve, he is a gentleman of many years of experience in the UK printed circuit industry. Even after several decades of circuit production, he has an energy and enthusiasm for manufacturing which are most infectious!

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Ladle on Manufacturing: Time to Show our Hand?

07-19-2017

It can be quite tough to satisfy the product requirements of the military and aviation industries, and rightly so. There are not many other parts that we manufacture that could result in a life-threatening situation should they fail when they are in use.

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Testing Times Ahead

05-29-2017

Bare board electrical test: For the most part, it does what it says on the tin. Current CAM software and test hardware means that in theory, it is a pretty simple exercise to make sure that a printed circuit matches the intended design. But are you getting the test you think you are?

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Drilling Deep

02-16-2017

Whether you stack high or drill thick panels, the dynamics of drilling are similar. When you overlay the outer-layer artworks you may notice that the holes on the exit side of the panel or stack have a much higher level of positional variation than the entry side holes.

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Material Matters

01-17-2017

Have you considered whether or not you could improve your multilayer yields by better use of your base materials? Perhaps the following could give you a few ideas of how this could help you.

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2016

Making Suppliers Work for You

12-15-2016

Every company has its own way of doing things. For some, the engineering team develops a detailed specification for the equipment they would like to purchase and this is put out to multiple suppliers for tender, along with full documentation for the commercial terms that will apply to the purchase. At the other end of the scale, a machine inquiry can be a simple phone call: “How much for a new machine?”

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