The manufacturing process
The data records of the customer are converted into the Ext. Gerber format (RS 274X).
The processed output file in the Extended Gerber Format can be supplied as preview if desired.
The copper-clad panels along with the drill entry material & a back-up-board are then cut to size.
The standard panel comprises of a 1.6mm thick base material, with a coating of 18µm copper on each side.
Drilling and pinning
At this stage the reference & tooling holes are drilled. The PCB-POOL panel is then pinned onto the CNC machine.
With the help of CNC drill machines the through-hole plated and component drills are produced. During this process, spindle speeds of up to 100,000 revolutions per minute are recorded.
Now an electrographic film (e.g. Palladium) is electroplated to the wall of the drill cavity, this allows for galvanisation with copper to occur at a later stage.
Because PCBs must be completley free of grease and dust, they are subjected to rigourous cleaning (e.g. by brushing) before proceeding to the next stage.
Under extreme temperatures and pressures the entire PCB-POOL panel is laminated with a photosensitive dry resist (LAMINAR 5038).
Using the previously generated photoplots the resist is exposed to UV light.
Developing the resist
The exposed panel is developed in a 1% sodium carbonate solution as it goes through a continuous flow system. This gives the individual PCBs on the panel their structure.
Conductor image structure in the electroplating
The tracks and pads which are developed, free of photo resist, are copper-plated to a thickness of approx. 35µm and fused with a 6µm -10µm tin film, protecting the tracks and pads during the final etching process.
The photoresist is stripped away with a 2.5% caustic potash solution. This lends itself to the immersion and spray coat processes.
The next step is the spraying on of a coat of ammonia solution onto the copper film, getting rid of any excess copper, while the galvanised tin protects the tracks and pads.
Only then will the tin be removed using a nitric acid based tin-stripper. This lends itself to the dipping or spraying processes.
Applying the solder mask
The solder mask is applied over the entire area using in a spray method.
Exposing the solder mask
Using a direct exposure laser, the solder mask is exposed with the highest possible precision.
Developing the solder mask
The development of the exposed production panel is in turn achieved through a continuous flow system in a 1% sodium solution. Hence all soldering points and pads, which are to be tin plated later, are cleared of solder mask.
Using a digital inkjet printer, the silk screen is immediately printed onto the solder mask.
At a temperature of approx. 150°C, the solder mask receives its final hardening in a continuous oven.
The pads developed free of the solder mask are coated with chemical Nickel-Gold surface through vertical baths. The gold layer acts as a protection of the nickel surface to ensure solderability.
The advantages as opposed to HAL are stress-free coating and the flat surface.
Hot Air Levelling (HAL)
On the surface coating the pads are tin plated in a hot-air tin-plating system at a temperature of around 270° C. During this process the PCB is immersed in liquid tin which is blown off with preheated air under a pressure of approx. 5 bar.
The data sheet for the used lead-free tin can be found with our specifications.
To prevent the panel from moving during routing, it is pinned down onto the routing machine bed.
The individual PCBs are removed from the production panel with the help of a CNC milling machine. A spindle speed of 40,000 rpm and a feed rate of 1 m/min. is used for this.
Laminating the resist
Under high temperatures and pressures the production panel is laminated with a photosensitive dry resist.
Exposing the resist
Using a direct exposure laser, the resist is exposed with the highest possible precision.
Developing the resist
The exposed inner layers are developed in a 1% sodium carbonate solution as it goes through a continuous flow system
Only at this stage are the individual layers pressed in a Multi-layer press at a max. temperature of 175°C and a cyclic time of 90 minutes for the layer structure.
The next stage is drilling. The following manufacture process is equally valid for both multi-layer and double-sided PCBs.