Laser Direct Imaging, also commonly known as LDI, plays a key role in the metal etching process. Traditional etching involves coating the metal plate with a polymer photo resist. After that, the digital design is exposed to the photo resist using ultraviolet light and photo tooling where the dark lines create a pattern on the surface of the photo resist. The sheets are then ran through a developing process that removes the polymer resist where the dark images were. The exposed metal is now vulnerable to the acid’s etching action. With laser direct imaging, the process is faster and more accurate. LDI uses a precise, computer-controlled laser beam to imprint the patterns in photo resist on the metal plates replacing the use of artwork and exposure to ultraviolet light.
LDI Process
The process of Laser Direct Imaging takes place in the following steps:
A digital image is created to the customer’s exact specifications, replacing traditional artwork.
Metal is also selected and sheared to size.
Metal is cleaned and then coated with the photosensitive resist.
The coated sheets are placed in the LDI and the digital data or image that is to be etched is exposed to the resist on both sides.
This whole process leaves behind the traditional use of costly artwork. LDI gives us a significantly reduced margin of error, and the result is as accurate as the design uploaded to the laser.
Benefits of LDI
Using Laser Direct Imaging instead of photo-tool helps manufacturers reduce:
• Superior image resolution • Precise two-sided registration • The use of Laser ensures clean cut edges • Able to image large sheets with precision • It can produce a higher volume of end products by working on multiple sheets concurrently • Any changes or corrections take only a few minutes and one doesn’t need to send it back
LDI with The LIMATA X3000
VACCO Etch has recently acquired a new machine that provides us with an edge in the competitive market. The LIMATA X3000 series is a Laser Direct Imaging equipment specialized in producing patterns on large sheets. The machine has a multiple wavelength setup, a user-friendly interface, and has great optical depth.
VACCO Precision Etched Parts is one of the paramount photo etching institutions throughout the western United States. With the addition of LDI, we can offer larger etched sheet sizes, with higher resolution imaging, and more affordable than large panel artwork.
Metals Etched by VACCO-etch
• Stainless steel • Titanium • Brass • Copper • Nickel alloy • Carbon & spring steel and • HyMu
We have in-house diffusion bonding, forming, welding, adhesive bonding, micro laser processes and a highly skilled hand assembly, inspection, and packaging line which allow us to enhance and customize your photo etching project.
Diffusion Bonding is a metalworking technique in which two metals are joined together by applying dynamic load and heat in controlled conditions. The diffusion of atoms at the interface of two joining metals takes place within these conditions which lead to uniform grain structure joint closing the interfacial voids leading to solid-state bonding.
Why Diffusion Bonding?
Diffusion bonding, used to join two similar metals, is a preferred choice over other metalworking techniques due to its superior bonded surface finish, especially when intricate structures with fine boundaries are involved. Some of the common techniques used in industry and their comparison with diffusion bonding include:
Technique
Principal Method
Profile Modification
Welding
High-temperature melting and diffusion of two joining metals using filler materials
Yes, melting deforms weld joint surface leading to profile modification.
Brazing
Similar to welding but fusion between two joint metals does not take place only filler material is melted between the joining metals to form a bond.
Yes, heat and melted filler material will modify the surface profile at joining faces.
Soldering
Joining of two metals by using third low melting point material which holds two metals together after hardening.
Yes, the melted filler can seep in between and over two joining faces.
Mechanical Fastening
Riveting or Nut/Bolt fastening is used where permanent joints are not needed but require a spacious design to accommodate the holes for rivets or bolts. The holes are also stress raisers.
No, Joint faces do not undergo any modification.
Adhesive Bonding
Adhesives are used to glue metal together, these glues could be epoxy or plastic agents and when applied between two metals that are then held under pressure the glue cures to develop a strong bond.
Yes, Glues are prone to creep into uneven surfaces and can’t be used for intricate joints with the varying surface feature.
Diffusion Bonding
Joint faces are kept under pressure and heated to diffuse the atoms across the boundaries of joining faces and hence result in strong bonding.
No, Metal surfaces with intricate features can be joined this way and hence can be used for the precision joining of metals with intricate features/flow paths.
In diffusion bonding two metals are joined without liquid fusion, melting, filler materials, or loss of weight and hence the characteristic metallurgical features of the parent metal do not change and the bond so developed is stronger. Diffusion bonding is extremely useful for manufacturing those components that have intricate internal structure or flow paths that will be difficult to machine using conventional manufacturing process when made from single-parent metal block. The component is designed in individual layers that can be etched separately, and in some cases combined with machined layers. These layers are then stacked to be diffusion bonded, creating a multidimensional component.
Diffusion Bonding Process
As mentioned above, diffusion bonding is solid-state bonding that means two surfaces that are to be bonded together do not undergo liquid state transition in the process of fusion and hence the process steps must be followed meticulously and when done so the bond is of high quality. The surface preparation, the pressures to be applied, the temperature to be maintained, the hermetic seal requirements and the environment in which to carry out the entire process are critical factors. The simplified steps of diffusion bonding are:
Surface Preparation – Ensure that the two surfaces that are being joined are smooth, debris-free, flat, and degreased. Good surface preparation is essential.
Pressure Loading – The two surfaces are then put together and pressurized to predetermined levels depending on the requirements of the bonded component, and the metallurgical limitations of the metals. This is done in an environment-controlled chamber, in which the process initiates by creating a vacuum to purify the process environment.
Dynamic Heating – The metals are then heated to predetermined levels (lower than the melting point of parent metals) to accelerate the atoms fusion across the boundaries of joining surfaces. The uniformity of temperature is crucial to ensure fusion equilibrium over the whole of the bonding surfaces.
When the process variables are precisely controlled the resultant bond’s strength and ductility matches that of parent metals and when put under tensile test the component should fail at parent metal and not at the bonded joint. The good diffusion bonded component cross-section should be structurally indistinguishable from the bond line and should be void-free.
Stages of Diffusion Bonding
During the entire controlled process of diffusion bonding, the bonding faces undergo the following four key stages:
Initial contact of parent metals.
Plastic deformation of asperities under pressure load due to creep.
Voids disappear as grain boundary diffusion under high temperatures. Grain diffusion plays a major role in plastic deformation.
Elimination of pores by volumetric diffusion.
Application of Diffusion Bonding
Diffusion bonding is used across multiple industries for its ease in manufacturing precision components with complicated internal features. Diffusion bonding can be used primarily with similar metals, metals of different thicknesses, and reactive metals. Common applications are in manufacturing of:
Microfluidics
Sensors
Miniature Heat Exchangers
Fuel Cells
Medical Devices
Electrical Components
Fluid Mixing Valve
The high precision offered by diffusion bonding is of the value +/-0.002” which enables its application in the manufacturing of critical components for various industrial applications such as:
Aerospace (Avionics/Space)
Automotive
Electrical Equipment
Scientific Equipment
Marine (Sensors/Equipment)
Electronic Fibers
VACCO offers a complete solution to all these industries from photo etching to diffusion bonding with its expert team of engineers and R&D team that works closely with clients to ensure a high-quality product. VACCO’s photo etching and diffusion bonding capabilities can handle thickness that ranges from 0.001” through 10”, a variety of materials including titanium and iron-nickel alloy. The use of ceramic or molybdenum materials to make fixtures ensures a high-quality finish of the product. The in-house welding and liquid penetrant inspection processes comply with the Performance Review Institute and national Aerospace and Defense Contractors Accreditation Program. VACCO’s Precision Etched Parts group is equipped with an in-house vacuum furnace to handle all your bonding needs. The Vacuum furnace consists of a 12” wide, 12” high and 12” deep hot zone capable of handling temperatures up to 1315℃. For more information and queries related to any of your bonding needs please reach out to us!
