Reflow oven

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A convection industrial reflow oven. Mark5 1826 Reflow Oven.jpg
A convection industrial reflow oven.

A reflow oven is a machine used primarily for reflow soldering of surface mount electronic components to printed circuit boards (PCBs).

Contents

In commercial high-volume use, reflow ovens take the form of a long tunnel containing a conveyor belt along which PCBs travel. For prototyping or hobbyist use PCBs can be placed in a small oven with a door.

Example of reflow soldering thermal profile. RSS Components of a Profile1.svg
Example of reflow soldering thermal profile.

Commercial conveyorised reflow ovens contain multiple individually heated zones, which can be individually controlled for temperature. PCBs being processed travel through the oven and through each zone at a controlled rate. Technicians adjust the conveyor speed and zone temperatures to achieve a known time and temperature profile. The profile in use may vary depending on the requirements of the PCBs being processed at the time.

Types of reflow ovens

Infrared and convection ovens

In infrared reflow ovens, the heat source is normally ceramic infrared heaters above and below the conveyor, which transfer heat to the PCBs by means of radiation.

Convection ovens heat air in chambers, using that air to transfer heat to the PCBs by means of convection and conduction. They may be fan assisted to control the airflow within the oven. This indirect heating using air allows more accurate temperature control than directly heating PCBs by infrared radiation, as PCBs and components vary in infrared absorptance.

Ovens may use a combination of infrared radiative heating and convection heating, and would then be known as 'infrared convection' ovens.

Some ovens are designed to reflow PCBs in an oxygen-free atmosphere. Nitrogen (N2) is a common gas used for this purpose. This minimizes oxidation of the surfaces to be soldered. The nitrogen reflow oven takes a few minutes to reduce Oxygen concentration to acceptable levels within the chamber. Thus nitrogen ovens typically have nitrogen injection in at all times which decreases defect rates. [1]

Vapour phase oven

The heating of the PCBs is sourced by thermal energy emitted by the phase transition of a heat transfer liquid (e. g. PFPE) condensing on the PCBs. The liquid used is chosen with a desired boiling point in mind to suit the solder alloy to be reflowed.

Some advantages of vapour phase soldering are:

This is also known as condensation soldering.

Thermal profiling

Thermal profiling is the act of measuring several points on a circuit board to determine the thermal excursion it takes through the soldering process. In the electronics manufacturing industry, SPC (statistical process control) helps determine if the process is in control, measured against the reflow parameters defined by the soldering technologies and component requirements. [2] [3]

Example of a modern thermal profiler Example thermal profiler.png
Example of a modern thermal profiler

See also

References and further reading

  1. Girouard, Roland. "Mark5 Reflow Oven". Heller Industries Website. Heller Industries Inc. Retrieved 28 September 2012.
  2. "Guidelines for Temperature Profiling for Mass Soldering Processes (Reflow & Wave)" (PDF). Retrieved 2019-07-01.
  3. "Modern thermal profiling device". Solderstar Website. Solderstar. Retrieved 28 September 2018.

General references

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<span class="mw-page-title-main">Microwave oven</span> Kitchen cooking appliance

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<span class="mw-page-title-main">Heat transfer</span> Transport of thermal energy in physical systems

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<span class="mw-page-title-main">Ball grid array</span> Surface-mount packaging that uses an array of solder balls

A ball grid array (BGA) is a type of surface-mount packaging used for integrated circuits. BGA packages are used to permanently mount devices such as microprocessors. A BGA can provide more interconnection pins than can be put on a dual in-line or flat package. The whole bottom surface of the device can be used, instead of just the perimeter. The traces connecting the package's leads to the wires or balls which connect the die to package are also on average shorter than with a perimeter-only type, leading to better performance at high speeds.

<span class="mw-page-title-main">Surface-mount technology</span> Method for producing electronic circuits

Surface-mount technology (SMT), originally called planar mounting, is a method in which the electrical components are mounted directly onto the surface of a printed circuit board (PCB). An electrical component mounted in this manner is referred to as a surface-mount device (SMD). In industry, this approach has largely replaced the through-hole technology construction method of fitting components, in large part because SMT allows for increased manufacturing automation which reduces cost and improves quality. It also allows for more components to fit on a given area of substrate. Both technologies can be used on the same board, with the through-hole technology often used for components not suitable for surface mounting such as large transformers and heat-sinked power semiconductors.

<span class="mw-page-title-main">Heat sink</span> Passive heat exchanger that transfers the heat

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<span class="mw-page-title-main">Wave soldering</span>

Wave soldering is a bulk soldering process used for the manufacturing of printed circuit boards. The circuit board is passed over a pan of molten solder in which a pump produces an upwelling of solder that looks like a standing wave. As the circuit board makes contact with this wave, the components become soldered to the board. Wave soldering is used for both through-hole printed circuit assemblies, and surface mount. In the latter case, the components are glued onto the surface of a printed circuit board (PCB) by placement equipment, before being run through the molten solder wave. Wave soldering is mainly used in soldering of through hole components.

<span class="mw-page-title-main">Reflow soldering</span> Attachment of electronic components

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<span class="mw-page-title-main">Selective soldering</span>

Selective soldering is the process of selectively soldering components to printed circuit boards and molded modules that could be damaged by the heat of a reflow oven or wave soldering in a traditional surface-mount technology (SMT) or through-hole technology assembly processes. This usually follows an SMT oven reflow process; parts to be selectively soldered are usually surrounded by parts that have been previously soldered in a surface-mount reflow process, and the selective-solder process must be sufficiently precise to avoid damaging them.

The role of the substrate in power electronics is to provide the interconnections to form an electric circuit, and to cool the components. Compared to materials and techniques used in lower power microelectronics, these substrates must carry higher currents and provide a higher voltage isolation. They also must operate over a wide temperature range.

<span class="mw-page-title-main">Flat no-leads package</span> Integrated circuit package with contacts on all 4 sides, on the underside of the package

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<span class="mw-page-title-main">Industrial oven</span>

An Industrial oven is a heated chamber that is used for a variety of industrial applications including drying, curing, and baking components. These different types of ovens can be useful in different industries such as bakeries and industrial manufacturing. These ovens play a big factor in many industries and without these machines, work all together would be very difficult. Also, without these machines work in factories, bakeries, and curing manufacturers would be nearly impossible without the industrial oven invented by Jordan Mott in 1833. John created the first coal oven called a base burner and had a ventilation to burn the coal efficiently.

<span class="mw-page-title-main">Oil heater</span> Type of convection heater

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<span class="mw-page-title-main">Soldering station</span>

A soldering station is a multipurpose power soldering device designed for electronic components soldering. This type of equipment is mostly used in electronics and electrical engineering. Soldering station consists of one or more soldering tools connected to the main unit, which includes the controls, means of indication, and may be equipped with an electric transformer. Soldering stations may include some accessories – holders and stands, soldering tip cleaners, etc.

<span class="mw-page-title-main">Thermal profiling</span>

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<span class="mw-page-title-main">Soldering</span> Process of joining metal pieces with heated filler metal

Soldering is a process of joining two metal surfaces together using a filler metal called solder. The soldering process involves heating the surfaces to be joined and melting the solder, which is then allowed to cool and solidify, creating a strong and durable joint.

<span class="mw-page-title-main">Conveyor belt furnace</span>

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