Die casting FAQ

Who are we?

Accent Die Casting and Fixtures is a part of Accent LED which was established nearly 30 years ago in Mumbai, India. As a jobshop die caster and PCB designer cum manufacturer Accent produces aluminum die casting fixtures and PCBs for OEM's (Original Equipment Manufacturer) products.

Accent manufactures dies, tools, jigs and the fixtures used in many industries by mainly two methods - by Die Casting and by using SPM (special purpose machines).

Accent uses aluminum die casting which involves molten aluminum injected with a die casting machine under force using high pressure into a steel die casting mold or tool to produce aluminum die casting parts.

The PCBs (Printed circuit Board) manufactured by Accent include single/double layer and metal clad PCBs for prototypes as well as for volume production. We have state of the art PCB manufacturing facility with extremely clean lab rooms which are free of foreign particles for testing and quality control.

We only cater to OEMs from different industries such as, lighting, automotive, appliance, communications, small engines, transportation, etc.

What is High Pressure Aluminum Die Casting

High pressure aluminum die casting is one of the most used industrial manufacturing processes in which molten aluminum is injected with a die casting machine under force using considerable pressure into steel die to produce finished products. Our expertise in manufacturing ensures excellent dimensional accuracy and smooth surfaces to avoid machining except for removal of flash around the edges and necessary drilling and tapping holes. High pressure die casting production is fast and inexpensive relative to other casting processes.

Several aluminum alloys are used for high pressure die casting parts to result in different mechanical and chemical properties. Aluminum high pressure die casting is the most preferred over other metals and alloys due to its increasing strength, light weight and reduced cost.

What is Die Cast Tooling ?

Die cast tooling comes in single cavities ( one part per cycle) or multiple cavities(more than one part per cycle). The tooling process in Accent is designed with only two slides which provides customers with efficiency in production at reduced cost. As a leading die casting company we ensure:-

  • Highly accurate design with all needed parts and features incorporated.
  • High quality dies which are able to stand high volume of production.
  • Careful planning to avoid machining and reduce cost.
  • Proper analysis of the wear of the dies in order to forecast the longevity of its parts.
  • Our In-House Die Cast Tooling capabilities include Die Casting dies and Die Casting inserts.

What is Die Casting porosity?

Porosity in die casting occurs due to manufacturing defect in which small pockets of void space and air remains within the metal and make it porous.

In Die casting, a particular amount of molten metal is put inside a shot cylinder, and then pounded with great force with a piston so as to force the metal into a die cast die. During this pounding process air inside the cylinder is forced along with the metal into the die casting die. It is a very fluid turbulent process. The air forced into the die with the metal and the metal already inside the die is forced out of the die through a series of gates, vents and overflows.

After this, the metal is left to cool down and harden or freeze inside the die. The metal is then removed as a die cast part. The same process is repeated over again.

In the worst case, porosity in die casting parts, weakens die casting parts, if the voids or pockets are very large. Porosity typically matters most in pressure tight die casting parts. When the air escapes through a die casting part, it is typically caused by porosity.

Why Aluminum Die Casting is more preferred than Steel Weldament?

Improved manufacturing is making Aluminum die casting replace steel welding in many industrial applications. The advantages of Accent Die Casting over the steel welded parts are as given below:

  • 3x greater axial load stregnth.
  • Fewer part failures in the field and fewer returns to the OEM.
  • Part weight is 2.5x less in aluminum saving money in shipping cost.
  • Production quantities (1,000's) within a few days instead of weeks as before.
  • Production rate is faster as an aluminum die cast part.
  • Raw part manufacturing cost is 2.3x less as an aluminum die cast part.
  • Finishing cost is less as an aluminum die cast part.
  • Better looking parts as a die cast part.

PCB FAQ

What is Scoring?

The “v” groove that cuts into the top and bottom surface of an array of multiple PCB’s or between a board and rails to be removed after assembly. The cut is usually 1/3 top, 1/3 bottom, leaving 1/3 uncut in the middle. This process is used when removing the tabs of a tab route is not a viable option, this does result in a less smooth finished board edge. The boards are typically set up side by side and end to end with the edges adjacent to each other. After assembly the boards are broken or snapped apart.

What is the milling?

Milling is the process of removing areas of copper from a sheet of PCB material to recreate the pads, signal traces and structures according to patterns from a digital circuit board plan.

What is the minimum clearance required from the edge to conductive path?

Clearance between the edge and conductive is required to prevent short to chassis. The gap also acts as an insulation to conductive elements of the board.

  • For outer layers :
    Minimum clearance between the PCB edge and milling line is 0.30 mm.
    Minimum clearance between the PCB edge and V-cut line is 0.50 mm.
  • For inner layers:
    Minimum clearance between the PCB edge and milling line is 0.50 mm.
    Minimum clearance between the PCB edge and V-cut line is 0.50 mm.

What are the differences between different surface finishes?

Generally customer specifies the surface finish. Although each surface finish has its benefits and limitations, several finishes are coming to the front of the pack to meet today’s advanced assembly needs.

HASL

  • More cost effective.
  • Most commonly requested finish.
  • Good shelf life. 268739
  • Quality compared to other finishes is lower.
  • Does not provide coplanar surface.
  • Not desirable for BGA and fine pitch SMT packages.
  • Its process introduces thermal excursion.

Immersion Silver

  • More industry accepted finish.
  • Provides a flat/planar surface.
  • Good for soldering fine pitch devices like QFPs and BGAs.
  • Does not subject the PCB to aggressive thermal excursion.
  • Good shelf life.
  • More cost effective compared to gold.
  • Handling, storage and assembly requires to follow some special guidelines.

ENIG (Electroless Nickel Immersion Gold)

  • Second most commonly requested finish.
  • Provides a flat/planar surface.
  • Highly solderable.
  • Fairly good shelf life.
  • The Nickel plating prevents Gold and Copper intermetallic migration.
  • Aesthetically very pleasing finish.
  • Difficult in controlling.
  • Could have compatibility issues with few solder mask types.
  • Highest costly surface finish of the group.

If it is my own design then do I need to share the impedance details with you?

Yes, if you give all the impedance detail, we will help you to decide the best possible stack up. And if you have already given the stack up detail, we will verify the stack up detail against impedance requirement and also we will make sure that you will get the required impedance in the finished PCBs.

If the impedance details isn't received from you, we'll produce the PCBs as requested by you with the chosen stack up only and we will not take care for the other parameters.

About Layout Service

What are the inputs required to avail PCB layout service ?

For PCB layout service we generally require the schematics and the bill of material. The schematics may be CAD generated or hand drawn data and schematic in PDF format.

Can you convert my existing finished hole design into surface mount?

Yes, we can convert your existing finished hole-design to surface mount.

How will your design team get in touch with us for any queries / doubts related to the layout service?

Our design team will get in touch with you for the queries, if any, through a detailed mail attached with the screen shot or send you PDF files for approval of the component placement. We will also, support you through phone calls and TeamViewer.

What is a schematic?

Schematic is the pictorial representation of all the significant components and it’s inter connections within a circuit, a device or a project with the help of standard symbols.

How to decide on the number of layers required for my design?

Use just 1 or 2 Layer PCB for the regular boards and 4 Layer PCBs for interfaces with controlled impedance (USB, Ethernet, LVDS). If you study the component datasheet, various component manufacturers suggest a similar layout guideline pointing out to the support of minimum layers and the number of signal and ground or power layer depending on the power supply and dielectric isolation requirement.