SMT-STENCILS

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The optimal product for every application: We make it easy to choose and enable you to save money.
Use photocad’s quick-pick tool now to find the right SMT stencil in next to no time.

Component size from 0603 smaller than 0603 smaller than 0603
Fine-pitch from 0,5 smaller than 0,5 smaller than 0,5
BGA µBGA, QFN µBGA, QFN
Laser cut SMT stencil
Brushed on both sides
100% by Stencil Check
Shipping in archival sleeve (cardboard)
Electro-polished with automated system
Silicon nano coating
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QUALITY FACTORS

There are good reasons to rely on our high-precision SMT stencils for solder paste printing. Well over half of all faulty connections in SMT assembly are due to defective solder paste. The company that masters this step is clearly ahead of the competition, because doing so minimizes the costs for reworking and scrap. At the same time, the quality of the stencil is crucial for a successful outcome. We use the laser-cutting process to manufacture our SMT stencils.


To optimize your solder paste printing, we use the following systems
for production of SMT stencils of the highest precision:

The latest laser-cutting technology with quick check system (CCD camera-based measuring system to monitor pad location and size)

LPKF Turbocut System:
special lens rotation mechanism in the laser cutting head to optimize the contours of circular openings to almost 100% (especially for BGAs)

Motorized beam expander:
software-controlled adjustment of the laser focus position for every desired thickness of material. The resulting precise focus setting ensures an optimally conical shape and low-residue laser-cut edges.

After-treatment by our FSL precision brushing equipment BM2/6 takes care of thorough, extra-fine polishing of all the laser stencils we supply.

100% SECURITY CHECK

We test the quality of SMT stencils with LPKF StencilCheck. The software creates a scanned image of the stencil and compares it to the production data. Discrepancies are displayed graphically on the screen. All test results can be summarized in a report and traced back. This is our guarantee of complete quality management.

LASER CUTTING

Extremely high energy density and focus make the laser an optimal tool for making precision cuts, and thus for the manufacture of high-precision SMT stencils.

The laser source we use generates a highly focused laser beam with a wavelength of 1064 nm (infrared). At its focal point, the energy density is so high that it can cut stainless steel sheets of 500 μ thickness. The accuracy of the laser systems is ± 2 µm. The thermal stress on the material along the cut is extremely small.

ELECTROPOLISHED SMT-STENCILS

Electrochemical polishing and deburring (electropolishing) improves a number of properties of metallic surfaces in one operation. Microroughness of the stencil surface is considerably reduced, and walls of openings are smoothened while finest burrs are removed.

ADVANTAGES OF ELECTROPOLISHING

  • The smoother the walls, the easier the solder paste comes off. Electropolishing considerably improves the pressure behavior especially for very small pad openings.
  • Electropolishing only affects the micron range without changing shapes or macrostructures. The SMT stencil is therefore not exposed to any mechanical or thermal stress.
  • The results are repeatable at high precision
  • The stencil is easier to clean.

THE PROCESS

Electropolishing is a reversal of the galvanizing process in which metal ions are deposited onto a workpiece.


Phase 1
For electropolishing, an electrolyte solution flows around the workpiece – in our case the stencil –  and gives it a positively charge so that it acts as an anode (plus pole). The cathode (minus pole) moves over the stencil in the electrolyte.

Phase 2
When a direct current is applied, metal ions are removed from the anodic stencil and move towards the cathode.

Result
The entire surface will be smoothened deburred to the finest grade – especially in the laser-cut interior walls.


Electropolishing machine

MOST ADVANCED TECHNOLOGY

In January 2013, Photocad had a highly sophisticated Poligrat EP110, L250-25 electropolishing system installed for polishing SMT stencils.

Photocad is the only manufacturer in Germany who has an automatic plant for electrochemical surface finishing of SMT stencils.

The plant that Poligrat designed specifically for Photocad performs the polishing process in a closed chamber, controlled by a Siemens CNC control system.

It considerably improves occupational safety compared to the conventional manual electropolishing process. Automation also ensures uniform high quality.

NANO-FINISHED SMT STENCILS

Nano-coated stencil sheets present much less dirt than other types of stencils. This means that finer stencil structures can be used repeatedly for printing, sturdily and securely, without having to clean the stencil.


Phase 1
The nanoparticles move freely within the substrate material on application.

 

Phase 2
The nanoparticles organise themselves during the residence time.

 

Phase 3
The surface is now cross-linked with the nanoparticles and protected.

 


Untreated surface
Treated surface

ADVANTAGES OF NANOTECHNOLOGY

  • The nano-finishing, after it has hardened, is chemically and mechanically extremely durable, heat- and frost-resistant, as well as UV stable.

  • Surface strength and scratch resistance are substantially improved, so that a mechanical abrasion in the course of normal use now has almost no effect. Also aggressive environmental influences have no negative impact.

  • The nano-finishing, in its completely hardened state, is totally harmless, neutral to the skin, and safe. There is no health hazard with proper processing and hardening of the nano-finished surfaces.

  • The illustrations show the action of water on an untreated surface (above) and a surface treated with nanotechnology (below).

  • The action of the water drops is quite different: The treated surface repels moisture much more vigorously, thereby reducing dirt adhesion.

STEP STENCILS FOR SPECIAL REQUIREMENTS


Numerous SMD applications require a large number of very different components on a circuit board and therefore different quantities of solder paste have to be applied in one printing pass. These differences in solder paste requirements can no longer be levelled out by the pad geometry and size of the apertures alone; what they need are stencils which have partial or local steps in thickness. They are called step, step-up/step down or multi-level stencils.

Working together with LPKF, photocad has developed its own method for producing step stencils, whose most impressive features are efficiency and flexibility.

FACTS

  • Steps with 25, 50 and 75 μm thicknesses possible
  • Surface coating possible
  • All standard stencil types


THE ADVANTAGES OF OUR STEP STENCILS

  • High precision, minimum tolerances
  • Different step heights possible
  • Suitable for many quick-clamping systems
  • Fast production to individual requirements
  • Very good value for money
  • Long service life due to high strength

STEP STENCIL REQUIREMENTS

Modern assemblies (modules) are usually made up of a large number of very small components and fine rasters (01005, 0201, QFN, QFP, etc.) and few larger type components (connectors, power components, etc.). This means that step stencils frequently need a greater thickness for increased paste volume only in a few, localised small areas. Essentially, additive or subtractive methods are possible to create these steps. Additive (step-up) stencils can currently only be made by galvanic (electroplating) methods, while subtractive (step-down) stencils are made by etching or machining. A special case is patchwork stencils, in which parts are punched out and then patches of variable thickness are inserted in these punchings. All these methods are expensive and time-consuming, which until now has prevented broad application.

With the new step-up stencil method, it is now possible for the first time to supply additive step stencils for a cost-effective price and quickly.

Our step stencils provide individual solutions for your special printing requirements.


Precise spot welding of the patch

THE NEW STEP-UP STENCIL METHOD

We developed our method for producing step stencils together with our technology partner LPKF, on the basis of extensive experience with our customers' requirements.

In the step-up stencil method, patches of different thickness are welded onto a base plate. The position of the patches is measured precisely by the LPKF laser machine and the patches are welded onto the base plate by spot welding. The welding gas used is nitrogen.

This method allows for variable geometry and ensures long durability of the patches.

After the patches have been welded on, the SMD layout is laser cut. When cutting the pad openings, the melting of the stainless steel sheet produces clean inner walls of the pad openings.

Another advantage of this method is that the distances between the step and the pad opening can be kept very small.

Step stencils made using this method also have a longer service life than step stencils made using subtractive methods, as the surface of the stencils is not damaged by our method, but instead its strength is actually increased by the welded-on patches.

The step pencils produced with this method can be further refined by electropolishing and a nanocoating.