4 SMD lines:

Maximum component placement per hour:    250.000 CPH Acc. IPC9850

Maximum component placement per year:    1.25 Billion components Acc. IPC9850

Our PCB assembly solutions cover conventional and SMT assembly. The manual assembly is carried out by highly skilled professional team. The SMT assembly is done by one of the latest high precision machines. Those integrated automatic production lines provide rapid, cost-efficient and qualitative mounting. All processes are completed in ESD protected rules. We are familiar with LEAN production, implementing 5S and JIT (just in time) methods.

SMD capacity and assembly

smd assembly
  • SMD components with packages 0201 to 55 mm2, connectors
  • Automatic SMD assembly for series production with Reflow-soldering and glue-technology
smd assembly
    • 4 HighTech SMD lines from the latest generation by JUKI with 2 integrated automats and a lead-free ovens for Reflow-soldering Vitronics and Heller
    • 2-D inspection for paste printing
    • Manual SMD assembly for prototypes and small series
    • Mounting of small bodies
    • BGA and uBGA
    • Supply and assembly of exotic elements
    • 100 % traceability – barcode system
    • SPI (solder paste inspection) in each SMD line

    Heller MK3 1809

    • 12 Zones for heating – up and down
    • 2 Zones with cooling system

    Vitronics Soltec MR933

smd assembly
    • 12 Zones for heating – up and down
    • 2 Zones with water cooling

About us

Steiner Elektronik GmbH was founded in 1969 in the city of Ruse (Bulgaria) as a manufacturer for the defense industry and specializes in the field of EMS services with a focus on the assembly of printed circuit boards.
The experience gained over these decades, our most modern production technologies and our well-trained, friendly and flexible team have given us the name of a high-performance electronics manufacturer in the field of SMD assembly on an international level.

Equipment: the story

From the middle of the 20th century, the assembly of electronic assemblies gained momentum due to the large-scale production of radio and TV sets.
Most of the production processes were already automated.
However, the assembly of the electronic assemblies was carried out manually.
The connecting wires of the building blocks were inserted and soldered through holes that were previously drilled in the circuit boards.
This type of assembly is known under the term THT assembly (abbreviation from the English: Through Hole Technology).
Through the development of technologies and the introduction of CNC assembly techniques, the possibilities have meanwhile been created for the automatized SMD assembly (abbreviation from English: Surface-Mounting Device) to gain in importance.

THT and SMD assembly: the processes

Both types of assembly are used today: THT assembly and SMD assembly.
With THT assembly, the connecting wires of the electronic components are fed through the holes and attached to the back of the board either manually or by machine.
In the next phase, the board is soldered manually or by machine.
If the circuit board is soldered by machine, either a selective or wave soldering system is used.

With the current SMD assembly, in contrast to conventional THT assembly, the components are not attached to the back of the circuit board with any wire connections, but are soldered directly to the circuit board using their connection surface.
In the first step, the solder paste is applied to the respective points using a template.
The elimination of holes and push-through assembly reduces the space required by the electronic components. In this way, a very dense, double-sided assembly can be carried out. Due to the space saving, a cost reduction and the cheaper and faster production of smaller devices is made possible. The shortened production time of the devices enables the production costs to be reduced. The small spacing between components requires improved high-frequency properties. Since there are no wire connections and smaller components are used, the weight of the products is reduced.
Furthermore, with the SMD assembly, assemblies with a smooth back are produced.
With SMD assembly, the soldering process takes place either in a soldering system (vapor phase) or in a reflow soldering oven. The reflow process can be used for top-side assembly, while wave soldering has become established for the underside.
Manual assembly is almost impossible with the SMD process and is only possible for the production of samples.
The high quality of the SMD assembly depends on the correct soldering.
Due to the small component dimensions, the soldering is controlled with the help of precise image processing systems such as AOI (from English: Automatic Optical Inspection), SPI (from English: Solder Paste Inspection) and AXI (from English: Automatic X-Ray Inspection).
The automatic optical inspection (AOI) of the optically testable points requires a higher manufacturing quality.
Finally, the circuit boards are separated from the panel using depanels.
If necessary, a protective coating can be applied.

Our services

Our company is characterized by innovation, dynamism, extensive competence, flexibility and customer orientation.
Our qualified, multilingual team will be happy to support you in completing your projects.
The concept of Steiner Elektronik GmbH includes the following range of services:
– Printed circuit boards: single-sided, double-sided, multilayer, aluminum, flex, etc.
– Assembly production: SMD assembly, 3D AOI, THT assembly and wave soldering N2, component procurement, selective soldering, selective painting, function test or IC test, cable assembly, device assembly, potting, ESD packaging.

Our production is certified according to ISO9001 / ISO14001 and corresponds to the standards IEC 61340-5-1, IEC 61340-4-1 and IPC610 class 2, whereby we carry out regular audits.


In order for Steiner Elektronik GmbH to procure the circuit board in accordance with customer specifications, it is necessary to provide us with the Gerber data, the information on the holes and the information on the structure of the circuit board.

The unequipped circuit board can also be provided at the customer’s request. In this case, for the assembly of the circuit board, we need the data for creating the SMD solder paste stencil based on the original data.
If the customer has ordered a utility version, we assume that he will provide us with the utility-based template data.
To avoid delays in delivery dates, sending the Gerber usage data 12 working days before the promised delivery date would be ideal.

Component procurement / provided parts:

As an EMS service provider, our product range includes not only the assembly of printed circuit boards but also the purchase of electronic components.
At the customer’s request, we can take over the entire procurement of materials that is required for the assembly of the assemblies.
We buy exclusively from verified global suppliers and manufacturers, whereby we can also order exotic components.
To ensure the quality of our equipment, all procurement sources are selected by us according to strict quality specifications and are repeatedly evaluated and audited.
Thanks to our barcode system, 100% traceability in the supply chain is guaranteed.
Another quality requirement of our suppliers is the ESD and MSD component treatment.
Due to the ongoing unpredictability of the market for electronic components, entire product groups are affected by delivery difficulties and price increases. These are caused by supply bottlenecks, delivery delays due to the Covid 19 pandemic and discontinuations.
Even with this challenge, we at Steiner Elektronik are still ready to carry out the assembly for our customers flawlessly and to deliver them quickly and on time by taking all measures for the supply and health security of our customers.
The stocking of the ordered items and timely delivery to our clients require at least long-term planning and early provision or ordering of the components required for stocking.
Unfortunately, sometimes that is not enough to complete your orders for the assembly of printed circuit boards without delays.
That is why long-term and timely disposition for problem-free assembly of your circuit boards is extremely desirable.


Thanks to our highly developed manufacturing techniques and the partnership with SET GmbH Steiner Elektronik Technologie, Germany, we offer our customers a wide range of EMS services.
The production and assembly of assemblies are part of our core competencies, whereby quick samples can also be produced in advance.

Steiner Elektronik – the expert for assembling assemblies

Since we have extensive specialist knowledge, the necessary infrastructure and logistics, you are making an excellent choice with us when it comes to assembling printed circuit boards.
As a certified electronics manufacturer, we offer our customers from the automotive, medical and electrical industries the highest quality and fast service for all aspects of assembly.
When equipping, we take into account all special customer requirements.
Thanks to our excellent specialist potential and state-of-the-art production technologies, we master all challenges, regardless of whether you want SMD or THT assembly.
Whether you would like to order prototypes or series production from us – we will cater to your special requirements.
We use two fully automatic JUKI assembly systems with two integrated SMD machines and reflow soldering ovens from Vitronics Soltec и HELLER to ensure the high-quality assembly of components.
In the case of series production with reflow soldering and adhesive technology, the automatic SMD assembly comprises 58,000 pieces per hour.
The assembly with components provided by the customer and unassembled circuit boards takes 1 week with the express service.
Our production is subject to constant quality control and is certified according to DIN EN ISO 9001: 2015 and ISO 14001: 2015.