Soldering and the making of PCBs

April 12, 2021

The smooth functioning of the mobile phones, laptops and smart household appliances that we take for granted today would be impossible without a printed circuit board (PCB). The ease we experience is the outcome of the unrelenting quest to connect electronic components in a stable, compact space most efficiently, in order to make devices that are more powerful than ever before. What started out in the 1940s as a jumble of point-to-point connections, with bulky wires, jumpers and cables, made way for insulated boards with copper traces on which components were soldered. Held together by soldering, these printed circuits allowed more components to fit in a given area (even as the components themselves were getting smaller), miniaturizing the final device and allowing for the automation of the PCB-making process.

Since the advent of miniaturization and automation, PCB design has made significant strides, and the main types being manufactured today are single-sided, double-sided and multi-layered circuit boards. Soldering plays an important role in many stages of modern PCB manufacturing, and the quality requirements of solder connections continue to increase.

Stages in PCB manufacturing

Today’s PCBs consist of four layers, the lowest being a fiberglass substrate that provides support to the board. On top of it lies the conductive copper foil or coating. A solder mask protects the copper layer, and a silkscreen forms the layer right on top. The main stages in the making of a PCB are listed below:

Circuit design: The circuit design is prepared as per the requirements, usually in the form of Gerber files.

CAM design: In this stage, the circuit design is processed for production. CAM reviews the files, verifies the order parameters, performs engineering reviews, creates the tools and sequences necessary for design, and queues the orders for manufacturing.

PCB manufacturing: Subsequent to CAM design, the necessary tracks are created on the board, and the excess copper is removed. The board area not to be soldered is protected with a layer of polymer resist, and the remaining areas are plated with solder, allowing for the easier mounting of components.

Component placing: Components may be placed on the board in two ways. In through-hole mounting, the leads of the components are inserted into the holes in the PCB. In surface-mount technology (SMT), the component is mounted onto the surface of the PCB.

Soldering and testing: Whether the components are placed by through-hole or surface mounting, they are soldered onto the PCB. Finally, a number of electrical tests are carried out on the PCB to ensure that it is running as expected.

Types of soldering

The three types of soldering are wave, reflow and selective. Wave soldering is the preferred technique for soldering through-hole components. Reflow soldering is the most common technique in PCB manufacturing and lends itself to soldering SMT components. Selective soldering is an automated alternative to hand soldering and is preferred in cases where the tight spacing of components is required.

Soldering in an inert atmosphere (notably nitrogen) has become increasingly popular in recent times. The advantages are clear. Soldering in an atmosphere of high-purity nitrogen reduces oxidization and improves the flow properties of solder as well as the spreading behavior and wettability of solder, all of which contribute to high-quality solder connections.

On-site nitrogen for quality soldering

An on-site nitrogen generator not only gives you control over the air purity required for soldering purposes (which is critical in ensuring appropriate solder spreading behavior at lower temperatures) but also reduces your operating costs (as compared to third-party supply) and ensures you have a constant flow of nitrogen gas when downtime can interrupt production.

Generating nitrogen on your own with an on-site nitrogen generator allows safer handling and ensures a lower carbon footprint. Additionally, on-site nitrogen generators, such as those from Pneumatech, are easy to integrate into existing systems.

Pneumatech designs and manufactures both standard and engineered on-site gas generator products. Explore Pneumatech’s full range of nitrogen generators. Or get in touch with us right away. 

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