Mass production pcb manufacturing Testing features2021-11-17
What is Mass production pcb manufacturing?
Mass production pcb manufacturing testing is one of the main objective methods for controlling the quality of Mass production pcb manufacturing. This method allows you to determine the smallest gaps in the production process – breaks, short circuits, surface resistance inconsistencies.
Basic methods for Mass production pcb manufacturing
The “Flying Probe” “equipment is a specialized hardware and software system designed to test PCB circuits for wire breaks or short circuits. MDA – defect analyzer – allows using probes to determine manufacturing defects of mounted printed circuit boards.
Mass production pcb manufacturing Design of the equipment is different
The design of the e mass production pcb manufacturing is different: there are horizontal, vertical devices with automatic loading. There are also various variations in the number of styli (from 2 to 4 on each side).
Note that in the process of checking by the “Flying probe” method, the manufacture of expensive additional equipment is not required, which significantly reduces the cost of checking the quality of the PCB. Also, With small batches, the absence of the need to create adapters helps to reduce the time spent on electrical testing.
Mass production pcb manufacturing Using adapters
mass production pcb manufacturing testing by the adapter method carries out using equipment that requires additional individual equipment – analyzers created for the required specification and configuration of printed circuit boards.
This method is the most accurate, but at the same time and overhead (since it requires the creation of adapters with individual technological parameters). However, it is also necessary to consider the fact that during serial production, the total time for checking one board using adapters is much less than electrical testing using the Flying Probe method.
Mass production pcb manufacturing Testing features
Electrical testing performs at the final stage of PCB production (etching). During testing, the electrical connections of the contact areas, points of the output of circuits check, deformation of the conductors / vias, the possibility of a short circuit exclude.
As a result, mass production pcb manufacturing defects appear – products in which there is no correspondence between working photomasks and spatial and electrical characteristics. Furthermore, Rejection is in progress.
As for the quality control method, it is defined quite simply:
if the total area of printed circuit boards is not more than 500 dm 2, then the most profitable testing method is the Flying Probe; if the area of the boards is from 500 dm 2, then it is economically more expedient to choose the adapter method.
Advantages of mass production pcb manufacturing testing
This reduces the overall production time of devices, by reducing the debugging processes of all their components.
The main stages of manufacturing printed circuit boards
Mass production pcb manufacturing is a complex multi-structure technological process that includes various methods (subtractive and additive). However, With the additive manufacturing method, a printed circuit board pattern is formed by chemical copper plating on a non-foil, previously protected, canvas.
With subtractive – the formation of a pattern occurs by eliminating areas of the material on the foil sheet. Note that the additive method is technologically obsolete and is not common in modern production.
First step: creating a foil-clad canvas
Foil is a flat dielectric with a layer of copper foil glued over it. Glass fiber laminate is often common as a dielectric. The thickness of the blade depends on the required electrical / mechanical strength (the optimum thickness is 1.5 mm).
|Option number 1: aluminum sheet with an oxidized surface +
|Option number 2: aluminum base|
|Feature: difficult to drill, the boards are one-sided, the pattern applies by chemical methods. Aluminum is easy to replace with steel or copper, thin laminated insulators, foil.||Feature: during manufacturing, the surface of the canvas is simple on the conductive areas of the pattern.|
Second stage: processing of blanks
Typical mass production pcb manufacturing consists of the following stages: drilling transition holes, creating patterns, metallization processes and applying protection to the canvas / holes, as well as marking products. If the dielectric plate has a multilayer structure, then in addition to these stages, pressing of several blanks add into a single final board.
Processing of any printed workpieces carries out using chemical, mechanical or electrolytic methods of reproduction of the required technological conductive pattern.
- Mechanical method
Processing by this method takes place with the help of engraving-milling machines. And other tools for mechanical removal of the foil layer.
Mass production pcb manufacturing Chemical method
When processing blanks by a chemical method, a protective layer first applies to the foil. And then the unprotected areas etch. Moreover, Protective layers in the industry come by prosopography – using sensitive ultraviolet photoresistors.
Also, the etching process often takes place in a solution of copper sulfate, ferric chloride or ammonium persulfate. Then the protective pattern washes off.
- Laser techniques
The process of pcb manufacturing of foil-clad fabric carries out using industrial prototyping complexes.
Stage three: applying the topcoat
Protective topcoats include water repellents, varnishes and long term contact integrity.
The final stage: control and quality control of products
The quality of industrial products checks by electrical testing and optical control methods. Such monitoring allows you to confirm the absence of short circuits and the integrity of the conductors.
List of steps for checking the quality of mass production pcb manufacturing:
- Drawing creation – checking the contours, diameters of the holes formed.
- Also, Uniformity and correctness of workpieces processing.
- Final check for the absence of any defects: short circuits, displacement of the conductive pattern, deficiencies / excess of the protective coating, etc.
High-frequency signals are transmitted
In this structure, high-frequency signals transmit in the top layer of Top Layer 1. And returned along the effective path on layer 2 (ground layer). Moreover, for high-frequency signals on the bottom layer, Bottom Layer 4, the power layer is the reference. And this requires coupling capacitors between the power layer and the ground plane.
In this structure, it is important to place the conductors for high frequency signals on the Top Layer. Thus, they will have a direct path to the ground. But if your design requires placing RF signal tracks on the bottom Layer 4, you can simply swap Layer 2 and Layer 3 to make this possible.