Production Process

Production Process for multilayer PCBs

There is no such thing as a standard printed circuit board. Each PCB has a unique function for a particular product. Therefore, producing a PCB is a complex process of many steps. This overview covers the most important steps when producing a multilayer PCB.

Production Process - for multilayer PCBs

When you order PCBs from the Maxwell Circuits, you are buying quality that pays for itself over time. This is guaranteed through a product specification and quality control that is far more stringent than other suppliers, and ensures that the product delivers what it promises.

In the production flow below you can see where the Maxwell Circuits process is unique or goes beyond the IPC standard

Maxwell Circuits PCB Specification is applied
Maxwell Circuits Specific production routines
Board manufactured using Maxwell Circuits approved equipment
Maxwell Circuits employees and dedicated teams
Clean room
All our factories are ISO 9001 and ISO 14001 certified

PPE - Pre Production Engineering

PPE Pre Production Engineering

Customer supplied data (Gerber) is used to produce the manufacturing data for the specific PCB (artworks for imaging processes and drill data for drilling programs). Engineers compare demands/specifications against capabilities to ensure compliance and also determine the process steps and associated checks. No changes are allowed without Maxwell Circuits permission.

MAXWELL CIRCUITS ADDED VALUE

MAXWELL CIRCUITS ADDED VALUE

With 12+ evaluated and approved factory pre-production engineers handling your data, Maxwell Circuits builds in security from the very start of the process.

Material issue

Material issue

Material of various types are received from approved sources and held in controlled environments until required. Using FIFO systems, specific material is released into production for a specific purchase order with base materials cut to the required sizes. All materials used can be traced back to their manufacturing batch.

MAXWELL CIRCUITS ADDED VALUE

MAXWELL CIRCUITS ADDED VALUE

We only use internationally known base materials – we don´t allow ‘local’ or unknown brands.

Inner layer

Stage 1 is to transfer the image using an artwork film to the board surface, using photosensitive dry-film and UV light, which will polymerize the dry film exposed by the artwork.

This step of the process is performed in a clean room.

Inner layer
Inner layer02

Inner layer etch

Stage 2 is to remove the unwanted copper from the panel using etching. Once this copper has been removed, the remaining dry film is then removed leaving behind the copper circuitry that matches the design.

Inner layer etch01
Inner layer etch02

Inner layer AOI

Inspection of the circuitry against digital “images” to verify that the circuitry matches the design and that it is free from defects. Achieved through scanning of the board and then trained inspectors will verify any anomalies that the scanning process has highlighted. Maxwell Circuits allows no repair of open circuits.

Inner layer AOI

MAXWELL CIRCUITS ADDED VALUE

All PCB’s are tested using Maxwell Circuits approved equipment and no track welding or open circuit repair is allowed. This provides increased reliability as there is no risk of repair failure, nor will this impair signal integrity.

MAXWELL CIRCUITS ADDED VALUE

Lamination

The inner layers have an oxide layer applied and then “stacked” together with pre-preg providing insulation between layers and copper foil is added to the top and bottom of the stack. The lamination process uses a combination of specific temperature, pressure for a specific time to allow the resin within the pre-preg to flow and bond the layers together to form a solid multilayer panel.

Lamination
Lamination02

Drilling

We now have to drill the holes that will subsequently create electrical connections within the multilayer PCB. This is a mechanical drilling process that must be optimized so that we can achieve registration to all of the inner layer connections. The panels can be stacked at this process. The drilling can also be done by a laser drill, which is the case in the attached production video.

Drilling

MAXWELL CIRCUITS ADDED VALUE

All PCB’s are drilled using Maxwell Circuits approved equipment which offer the best performance such as positional accuracy.

MAXWELL CIRCUITS ADDED VALUE

PTH Plated Through Hole

PTH provides a very thin deposit of copper that covers the hole wall and the complete panel. A complex chemical process that must be strictly controlled to allow a reliable deposit of copper to be plated even onto the non-metallic hole wall. Whilst not a sufficient amount of copper on its own, we now have electrical continuity between layers and through the holes.

PTH - Plated Through Hole
PTH - Plated Through Hole 003

Panel plating

Panel plating follows on from PTH to provide a thicker deposit of copper on top of the PTH deposit – typically 5 to 8 um. The combination is used to optimize the amount of copper that is to be plated and etched in order to achieve the track and gap demands.

Panel plating

MAXWELL CIRCUITS ADDED VALUE

MAXWELL CIRCUITS provides through hole plating of 25um nominal, as standard (equates to IPC class 3). This is 25% more copper than achieved with IPC class 2 and provides greater reliability of the via structure and improved z-axis expansion performance.

Panel plating008

Outer layer image

Similar to the inner layer process (image transfer using photosensitive dry film, exposure to UV light and etching), but with one main difference - we will remove the dry film where we want to keep the copper/define circuitry - so we can plate additional copper later in the process.

This step of the process is performed in a clean room.

Outer layer image
Outer layer image008

Pattern plate

Second electrolytic plating stage, where the additional plating is deposited in areas without dry film (circuitry). Increases the plating thickness to meet demands including Maxwell Circuits demands with an average of 25um / min 20um through the hole. Once the copper has been plated, tin is applied to protect the plated copper.

Pattern plate

MAXWELL CIRCUITS ADDED VALUE

Maxwell Circuits provides through hole plating of 25um nominal, as standard (equates
to IPC class 3). This is 25% more copper than achieved with IPC class and provides greater reliability of the via structure and improved z-axis expansion performance.

MAXWELL CIRCUITS ADDED VALUE0856

Outer layer etch

This is normally a three steps process. The first step is to remove the blue dry film. The second step is to etch away the exposed/unwanted copper whilst the tin deposit acts an etch resist protecting the copper we need. The third and final step is to chemically remove the tin deposit leaving the circuitry.

Outer layer etch
Outer layer etch5559

Outer layer AOI Automated Optical Inspection

Just like with inner layer AOI the imaged and etched panel is scanned to make sure that the circuitry meets design and that it is free from defects. Again no repair of open circuits are allowed under Maxwell Circuits demands.

Outer layer AOI - Automated Optical Inspection

MAXWELL CIRCUITS ADDED VALUE

All PCB’s are tested using Maxwell Circuits approved equipment and no track welding or open circuit repair is allowed. This provides increased reliability as there is no risk of
repair failure, nor will this impair signal integrity.

MAXWELL CIRCUITS ADDED VALUE9898989

Via hole plugging

Using solder mask ink or epoxy resin and a prepared stencil, with holes in the stencil that align with the via holes we wish to plug, we use a screen printing process to push ink or resin into holes. Unlike solder mask we are trying to push ink through the holes in the PCB and judge quality based upon the Maxwell Circuits demands of ≥ 70% fill.

This step of the process is performed in a clean room.

Via hole plugging

MAXWELL CIRCUITS ADDED VALUE

With ≥ 70% solder mask fill on type VI via holes, Maxwell Circuits provides less risk of via holes causing rejection during assembly.

MAXWELL CIRCUITS ADDED VALUE98566

Solder mask

Solder mask ink is applied over the whole PCB surface. Using artworks and UV light we expose certain areas to the UV and those areas not exposed are removed during the chemical development process – typically the areas which are to be used as solderable surfaces. The remaining solder mask is then fully cured making it a resilient finish.

This step of the process is performed in a clean room.

Solder mask

MAXWELL CIRCUITS ADDED VALUE

Maxwell Circuits defines solder mask thickness, IPC does not. With ≥ 5um on the knee of the track and between 10-30um on the surface Maxwell Circuits PCB’s offer improved electrical insulation and an improved resilience to chemistry or mechanical force that could cause loss of solder mask.

MAXWELL CIRCUITS ADDED VALUE8566358

Surface finish

Various finishes are then applied to the exposed copper areas. This is to enable protection of the surface and good solderability. The various finishes can include Electroless Nickel Immersion Gold, HASL, Immersion Silver etc. Thicknesses and solderability tests are always carried out.

Surface finish
Surface finish885269

Profile

This is the process of cutting the manufacturing panels into specific sizes and shapes based upon the customer design as defined within the Gerber data. There are 3 main options available when providing the array or selling panel – scoring, routing or punching. All dimensions are measured against the customer supplied drawing to ensure the panel is dimensionally correct.

Profile

MAXWELL CIRCUITS ADDED VALUE

All PCB’s are profiled using Maxwell Circuits approved equipment which offers the
best performance such as positional accuracy. Default tolerances are applied to all designs if none are defined on the procurement documentation.

MAXWELL CIRCUITS ADDED VALUE88569925

ET Electrical Test

Used for checking the integrity of the tracks and the through hole interconnections – checking to ensure there are no open circuits or no short circuits on the finished board. There are two test methods, flying probe for smaller volumes and fixture based for volumes.

ET - Electrical Test

MAXWELL CIRCUITS ADDED VALUE

Maxwell Circuits do not allow no track welding or open circuit repair.

MAXWELL CIRCUITS ADDED VALUE798465456

Final inspection

Visual checking the PCB against acceptance criteria and using Maxwell Circuits “approved” inspectors. Using manual visual inspection and AVI - compares PCB to Gerber and has a faster checking speed that human eyes, but still requires human verification. All orders are also subjected to a full inspection including dimensional, solderability, etc.

Final inspection

MAXWELL CIRCUITS ADDED VALUE

Each PCB is inspected against the 100+ points as defined in the Maxwell Circuits product specification and every batch is subject to a full evaluation prior to shipment to ensure the PCB’s are produced to the highest standard. Our onsite Maxwell Circuits QC teams oversee the verification processes.

Final inspection8852369
Packaging

Packaging

Boards are wrapped using materials that comply with the Maxwell Circuits Packaging demands (ESD etcetera) and then boxed prior to be being shipped using the requested mode of transport.