18/05/2021

Stencils for SMT assembly

The company Rezonit, acknowledged PCB manufacturer No. 1 in Russia, is also one of the leaders in the markets of contract assembly of electronics and the production of stencils for SMT. Naturally, the negative macroeconomic factors that we had to face last year also affected Rezonit. But even in these conditions, the company does not try to take a defensive position in the market, reducing development programs, but continues to invest in new production facilities, improving technologies to meet the customers' needs. This applies to all areas — both the PCB production and contract assembly, and stencils manufacturing.

Andrey Maksimov, Head of the Stencils department at Rezonit, told us more about the stencils production.

Andrey, how is the Stencils production developing in the current conditions? Tell us about the main technological changes in recent years?

We have fully implemented the investment program planned for 2020 for stencils, thanks to which we can offer unique technologies and services on the Russian market.

One of the major innovations was the improvement of the production technology of multi-level stencils. Although this product is becoming more and more popular in the world, it is still not as popular with Russian consumers as with their European counterparts. Using the example of our contract production, we note that previously we had to use multi-level stencils only a few times a year, but now several orders per month are made with this technology.

There are several fundamentally different ways to obtain a different thickness of a sheet of steel. Electrochemical and mechanical methods are widely used in Europe, when zones with a smaller thickness are obtained by etching or precision depth milling. Also, these methods are combined with the welding of steel pieces on areas where a greater thickness is required than on the main area of the sheet. Precision etching and depth milling techniques require very serious investment. There are companies in Europe that specialize in performing these works. The stencil manufacturer sends an order for milling or etching and within one or two days receives a sheet of finished multi-level steel. It remains only to carry out standard work like cutting apertures, polishing and other additional options.

In the Russian market, such services are simply not available, and the only method available is precision laser welding. It consists in the fact that cutouts are made in the main sheet in areas where a different thickness of steel is needed, and pieces of steel of a different thickness are welded into these zones. Welding is performed by a continuous welding joint on both sides of the sheet. The total welding depth is more than 70% of the sheet thickness, which ensures high connection strength. At the moment, we have not received any complaints related to the welding strength of the StepUp and StepDown areas from customers or from the technologists of our assembly production.

The specialists of the stencil section mastered this technology a few years ago, but in 2020 we purchased and put into operation the latest machine with an integrated option for welding the StepUp and StepDown areas and all the necessary tooling.

Thus, at the moment, we offer our customers StepUp and StepDown stencils, made at the most modern technological level.

What new services, in addition to the listed ones, do you offer?

Framed stencils production has also been innovated. These products are in steady demand in the mass production segment, as well as among customers with a small range of products. We have assembled a new mesh tension system on the frames, in which the mesh is stretched simultaneously on all four sides using pneumatic cylinders, which has allowed a higher and more uniform level of mesh tension that meets all accepted standards.

We have mastered the production of framed stencils of increased size. Now the laser cut stencil function is standard for our equipment. The maximum frame size we can make is 1500×740 mm with a working field of 1250×550 mm. Such stencils, for instance, are used in the mass production of LED lamps.

What types of stencils are in high demand?

The demand for stencils with electroless polishing is constantly growing. Often, this option is simply necessary when performing the assembly of components with a small step, and we could not ignore it in our modernization program. The main goal of improving the process is to achieve maximum uniformity of processing over the entire polished surface. We also started ultrasonic cleaning of all polished stencils before legend printing and packaging.

Not so long ago, we offered our customers a stencil storage system in two versions. Many customers liked this method of storage, and they used it at their site. It is no wonder, since this system has been used in our assembly production for many years, and we consider it the best one.

For our customers, we add a zip bag for the storage system with each order of standard size stencils (600×600 and 600×800)  and we are going to continue this practice.

Have the prices of stencils increased because of the crisis?

Despite the depreciation of the rouble and the general increase in prices for both the materials themselves and transport logistics, we have so far managed to keep the main price list the same as it has been for several years.

However, if the situation is similar to the one in the PCB market now, when the prices of basic materials have increased twice , then, I am afraid, we won't be able to avoid price increase.

How is the stencil delivery organized?

We offer our customers express delivery of orders by DHL at very affordable prices. For now, this service is the best in Russia. An interesting fact: since the spring of last year and until the end of March of this year, for well-known reasons, the pickup of products from our warehouse was impossible, and customers who had previously picked up products from the warehouse themselves were forced to use express delivery. Based on the feedback received, we can say that most customers really appreciated the convenience of express delivery and are not going to return to pickup. Large demand for stencils allowed us to avoid a significant increase in the delivery price in 2021 due to the increased volume, despite a sharp general increase in the price of express delivery on the market.

How to order a stencil as quickly as possible?

I definitely advise you to use Personal account on our website, since this option has undeniable advantages: as soon as you place an order in Personal account, it immediately appears in the internal database, the files are placed where they should be, and the processing engineer can immediately deal with it. When an order is received in another way, it must be entered into the database manually, which inevitably leads to a loss of time.

If the stencil order is linked to the board order in Personal account, this allows you to avoid a very common mistake, in which the PCB is ordered in a multiplicated form, and the stencil is made for a single PCB. In our experience, the opposite situation also happens. If the stencil order is linked to the board order, the engineer will prepare the stencil for the board project that has gone into production.

If you use Personal account, such errors are simply excluded. In addition, there is an opportunity to combine the delivery of the board and the stencil and save on logistics.

Tell us about the order option with the file prepared for production.

We accept a prepared file for a stencil-cutting, this helps not only to save time and money, but also to minimize the number of errors.

Firstly, the customer always knows the specifics of their assembly production better than we do and can optimize the stencil exactly for the necessary technological capabilities.

Secondly, the preparation of the stencil project takes place according to the documents that the customer sends. Not always in the project there are layers of paste on the layers of contact pads and masks, which leads to an ambiguous interpretation of the project and complicates the correct preparation of the file for production. Placing an order with a ready-made file allows you to save money — we offer a discount on such orders and in Personal account this option is implemented intuitively.

We are pleased that the share of orders placed through Personal account is steadily growing, including orders with cutting files. But, as always, we want more than that, because it benefits both our client and us as a manufacturer.

What are your future plans?

For this year, we also have a number of changes of technology and services, but we will talk about them after they are implemented.

We are not going to stop, even in a difficult market situation.

Thank you for an interesting conversation.

The interview was prepared by Leonid Chanov