| Operation |
Explanation |
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| Laminating |
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| The basic material is first roughened by chemical means (micro etching) to create a good adhesion area for the photosensitive dry film resist (photoresist for short), which is applied next (laminating). |
| Punching |
The layers are provided with a reference system, comprising four oval holes, which ensure accurate adjustment in subsequent stages of the production process, e.g. pressing and exposing.
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| Exposing |
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| On the photosensitive layer a track pattern is copied from a film, by illuminating both the layer and the film. A negative film is used for this, which means that the tracks are exposed so that they are maintained. The film has the same reference system as the layer and hence the position of the tracks is fixed. |
| Developing |
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| During developing, the unexposed photoresist is removed. Thus there remains only photoresist on the track pattern. |
| Etching |
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| All the copper cleared during developing is etched away. What is left is the photoresist-coated copper track pattern. |
| Photoresist stripping |
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| The remaining photoresist is removed by stripping. A bare track pattern remains on the basic material. The layer is then checked for any faults. |
| Browning or blackening |
To achieve a good adhesion while the different layers are being pressed together, the copper tracks are covered with a copper oxide coating. The oxide ensures that the surface is roughened further, enlarging the adhesion area. The colour of this coat is either brown or black. Whether browning of blackening is applied depends on the temperature during pressing. At high temperatures the browning process is employed. |
| Pressing |
The layers are pressed together to form a multilayer. During pressing an epoxy is laid between the layers. This material has the property that, after solidification, it can be made to flow again. It acts as a glue, bonding the different layers. |
| Deblackening |
The exterior of the multilayer is deblackened using hydrochloric acid. |
| Drilling |
Holes are drilled at the spots where components are to be placed later or where connections between layers need to be made. |
| Removing drill grease |
Drill residue is chemically removed, using permanganate. For teflon and polyamide, plasma etching is used. |
| Glass etching |
Drilling often causes glass fibres contained in the basic material to protrude in the drilled hole. Through glass etching those fibres are cleared away. |
| Plating |
 |
| To render the holes electrically conductive, a copper coating is currentless applied to them. This is done in the PTH (Plating THrough) line. In this line also a thin layer of electroplated copper is additively transferred to them (electroforming). |
| Laminating |
The multilayer is mildly etched, to remove all oxides and finger marks. Next, photoresist is applied to it, the so-called laminating. |
| Exposing |
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| Exposure is now through a positive film, i.e., the track pattern in this case is not illuminated. |
| Developing |
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| During developing, the unexposed part, the track pattern, is cleared. |
| Pattern plating |
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| On the track pattern, a thin copper layer is applied electrolytically. This is done in a line of chemical baths. |
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Tin mask |
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| Next a thin layer of tin is electroplated additionally. This tin mask, which only adheres to the cleared copper, serves as an etching mask. |
| Photoresist stripping |
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| Now the photoresist is removed (stripped). The result is a copper board with a thin layer of tin on the track pattern. |
| Etching |
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| The multilayer is then etched. This means that any copper not coated with tin is removed. |
| Tin stripping |
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| The tin on the track pattern is removed, so that on the outside of the board only the basic material remains with on it the track pattern. |
| Soldering mask |
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| The board is again etched mildly to get rid of oxides and any finger marks. Then, a permanent photosensitive layer is applied, the so-called soldering mask. This layer is melted-on such that it is effectively integrated with the board. |
| Exposure |
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| The soldering mask is exposed, at the spots where no soldering needs to take place during the hot air levelling (see below). |
| Developing |
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| During developing, everything that was not exposed is removed. Thus islands, holes etc. are freed from unwanted contacts. On track sections and holes where no soldering needs to take place, the soldering mask is kept on as a protective layer. |
| UV/oven curing |
By exposing the board to UV light and subsequently drying it in an oven, the soldering mask is hardened. |
| Hot Air Levelling |
 |
| The multilayer is once more etched mildly, after which a thin layer of lead tin is applied to the cleared copper, as a shield for this fast oxidising material. First the board is provided with a thin layer of soldering flux (a liquid that furthers a proper adhesion between copper and lead tin). The board is then dipped into a lead tin bath, and immediately afterwards blown clean under high pressure (Hot Air Levelling, HAL). This ensures that the lead tin only attaches to the copper and that its surface is moreover nice and smooth. After the HAL process the board is cleaned and dried in the washing line. |
| Milling |
Now the board is milled to the correct form and dimensions. |
| Bare board test |
All connections that in theory should be on the board, are checked for presence. |
Subprocesses |
| Plotting |
Technical work preparation ensures that the films are automatically plotted.
When the films have been plotted, they are developed. The films of inner layers are inspected, examined and punched. Of the outer films, diazos are made. When these have been checked, the films are passed to the exposure room. |
| Inspection Service |
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| All layers and end products needing to be checked pass through this department. Intricate products and layers with very detailed patterns are handled by the AOI (Automatic Optical Inspection) section, and products of a lower degree of difficulty are inspected manually. This may occur several times in the course of the production process. Additionally, products' outer layers are sometimes examined for any damages. |
| LAB |
Different activities take place in the LAB. The Probot Bare Board Tester functionally checks products for shorts and open connections. Any faults the tester comes across are verified manually. It is also determined if the faults are internal or external. The aim is to deliver qualitatively sound products, which do not require repairs. The product specialists of the LAB are assigned to follow fast protos. From kick-off until the end of the production process they monitor the protos, ensuring that the stipulated 5 days' delivery time is observed. They further supervise special products. Specials are highly complex and intricate products and the process of their production has several critical points. Product specialists ensure that the production of specials proceeds smoothly. When new technologies are introduced, they support the technologists, by taking the products under their wing.Finally, product specialists support staff in general. The objective is for staff to be capable of being deployed multifunctionally. |
| Analytical Chemical Laboratory |
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The analytical chemical laboratory's task is to monitor the quality of the various chemical baths. With the aid of a variety of tools, including titrators and atomic absorption spectrophotometers, all kinds of concentrations (acids, bases, metal contents) are determined. On the basis of the measuring results, any necessary additions to a bath are calculated, using an analysis and addition report. The analytical chemical laboratory works for several departments, prominent among which are the department of BB&S and the waveguide department. The laboratory further performs analyses for Galvano Hengelo BV and the water treatment agency.
The analytical chemical laboratory's work has many facets:
- Analysis methods are maintained and continually kept up to date. This also applies to the associated equipment.
- Bath lines are analysed.
- Support is lent to product development (through tests).
- Specifications and instructions are drawn up and reports issued.
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| Quality Service |
The quality control officers' task is to check that the products satisfy the appropriate specifications, for instance those of IPC Class 2. This they verify by examining product cross-sections, which are machined to form microsections.
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