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AS 9100 Rev.C & ISO 9001 CERTIFIED 

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What does NBP's Chemical Milling Solution do?
NBP has a proprietary chemical milling solution for cleaning zinc die cast based parts. This solution is a chemical bath and does not require electrical current. It will remove the zinc oxide layer and prepare the part for plating. It can clean out cold shut areas, remove minor flash, debris and burrs. Our normal chemical mill removes .0003" - .0006" of material but can be increased to about .001". The advantages of Chemical Milling is that a thin layer of zinc oxide or carbonate deposited over a pure zinc die cast surface is removed and the potential for casting blisters can be eliminated. This also allows for high temperature applications without the casting blisters to appear under the intermetallic stresses that are formed from the copper plate.
Can you explain your process of plating Zinc Die Casting?
With the exception of zinc plated parts, all zinc die-castings are processed as follows: preclean, mill, copper strike, and copper plate.
Preclean: A two step process to remove most synthetic, petroleum, vegetable, and animal based fluids used in die-casting and machining operations.
Mill: A controlled removal of the outer layer of die-cast. This process can remove flash, surface die-cast blisters, and modify dimensions if necessary. This step is essential to improve the adhesion of the subsequent copper plating.
Copper Strike: The copper strike is a specially formulated copper solution designed to provide excellent adhesion to the die-cast surface. The thickness of the strike is approximately 50 millionths of an inch.
Copper Plate: The copper plate seals the zinc to protect it from environmental exposure. Also, copper is used to modify dimensions. After the minimum thickness is achieved, we often add more copper to build dimensions. A thick, continuous copper plate is essential to protect the part from subsequent plating solutions which are corrosive to raw zinc.
Final Plate: After copper plating, the parts may safely be plated in nickel, tin, EN, etc.

What is the difference between an Electrolytic & an Electroless Bath?
Unlike conventional electrolytic nickel, no electrical current is required for deposition of Electroless Nickel. The electroless bath provides a deposit that follows all contours of the substrate exactly, without building up at the edges and corners. A sharp edge receives the same thickness of deposit as does an internal diameter.

Do you have any Black Finishes?
NBP has a variety of Black Finishes (in order of increasing cost)

NBP's Econo Black - NBP's own formulations - This molybdate black goes directly on zinc die cast. After the molybdate coating is applied, the parts are submerged in a seal composed of chromates and phosphates that enhance the salt spray resistance of the coating. An organic coating, water dip lacquer, is applied as a final coat to protect the finish and improve appearance.
Zinc & Black Molybdate - Similar to Econo Black, but this molybdate black is applied over a bright zinc plate to yield a glossy, plastic like black finish. The corrosion characteristics can be improved with a seal and/or lacquer as required.
Black Electroless Nickel - Parts are Electroless Nickel plated and then blackened to give a metallic brown / black appearance. This coating is used for a variety of applications from color identification to eye appeal.
Black Electrolytic Nickel - ULTRA CONDUCTIVE - This finish is not as intense as the Zinc & Black Molybdate but has excellent eye appeal, yet this finish in contrast to the other black finishes is very conductive. This coating was developed for automotive applications where conductivity and low reflectivity are important.

Why would I find Black Spots on Tin & Tin/Lead Plating?
Fretting is a common problem with Tin Plating. This is surface damage created when there is relative motions and strong contacts between parts, usually during shipping and handling. The tin plating shows black or worn spots caused by rubbed or scratched by another part. This oxide does not effect the parts functionally. They are still solderable. A way to eliminate fretting is by changing the type of packaging. (Layer packing or plastic trays are recommended) - Metal Finishing Guidebook 1997

Are there many problems associated with Tin Plating?
There are many problems associated with tin plating. One of which is whiskering, like cadmium and zinc, thin needle-like crystals known as "whiskers" form within a period after plating that may vary from a few weeks to several years. A whisker may measure up to .0001" (2.5um) in diameter, and grow spontaneously to a length of 0.375" (10 mm). Conditions that tend to promote the growth of whiskers are compressive stresses and uniform temperatures for long periods of time. In most applications, these slender microscopic crystals would be unnoticed and harmless, but in closely spaced electronic circuits they are capable of carrying sufficient current at low voltages to cause serious short circuits or a corona discharge.

When the formation of whiskers is known to be a potential problem, the condition may be prevented by specifying that a small amount of lead be included in the tin deposit. While 1-2% lead is adequate to substantially reduce the risk of whiskering, it is customary to specify a 93% tin - 7% lead alloy to assure that the alloy remains sufficiently high in lead under all conditions of electroplating to prevent the formation of whiskers. Small quantities of antimony, copper or nickel in the tin deposit have also been reported to prevent the formation of whiskers.

What finishes are good for soldering?

The most widely used finishes for soldering are Tin, Tin/Lead & Gold.

What is electroplating?
Electroplating is a process by which metal in ionic form migrate from a positive to a negative electrode. An electrical current passing through the solution causes objects at the cathode to be coated by the metal in solution. The size, shape and weight of the objects being plated determine how they will be plated.

Electroplating is done to protect, beautify, insulate or increase the corrosion resistance, conductivity, or solderability of metal objects. It demands as much skill as any modern endeavor. Platers immerse objects into a variety of chemical baths in order to change their surface condition. Regardless of the finish being applied, the parts must be "surgically" clean.

What precious metals are used in electroplating?
Precious metals commonly used in electroplating and surface finishing operations include gold, silver, indium, ruthenium, palladium and rhodium. Factors that influence the selection of precious metals are their contact characteristics, corrosion resistance, heat resistance, reflectivity, solderability, color and wear resistance.

Silver has an advantage of its relative low cost, but it is susceptible to tarnishing when exposed to sulfur in the atmosphere.

Gold has excellent solderability and electrical characteristics. The hardness and appearance of gold can be modified with different alloying elements.

Indium is a precious metal that has the unique quality of cold fusing at room temperature with aluminum and copper. This cold welded bond keeps out oxidation between the indium plated part and the aluminum or copper base material allowing for excellent electrical and thermal transfer contacts. This coating is the UL approved finish for connecting aluminum wiring to a copper receptacle.

What is Pickling & Acid Dipping?
Metals can be immersed into solutions of acids to remove metal, metal oxides, heat-treat scale, and foreign metals. Such treatments generally leave the surface chemically clean and ready for further processing. The general process is to solvent, emulsion, or alkaline clean the parts prior to acid immersion, so that the acid solutions will wet and/or etch uniformly.

Common Plating/Casting Issues
Blisters (Bumps / Bubbles / Pimples / Pockets) - A thin sac containing liquid, air, or diecast particle on or near the surface.

Corrosion / Black Spots / Fretting - Discoloration of the surface

Cracks - A linear discontinuity in the metal surface which fractures the material.

Exposed Base Metal - Metal is exposed due to lack of any plating (This condition can be verified at up to 10X magnification with Microscope lighting.)

Flaking - A separation of peeling of plating.

Flash - Excess casting material at parting lines.

Foreign Material - Excess material such as tumbling media or pieces of sprue or gate wedged into the part.

Incomplete Fill/Nicks - Holes that are deeper than the skin of castings.

Slivers - A long thin piece of casting or plating.

How do I go about getting a quotation?
All we need is a blueprint or description of the part, finish specification (see Capabilities), tolerance or thread that should be monitored and quantity.
Email -
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Fax - (732) 846-9779
Mail - 1010 Jersey Ave. New Brunswick, NJ 08901

What is the average lead time?
NBP understands the importance of expediting your parts as quickly as possible. It is not uncommon for us to receive, plate and ship parts in the same day. We will try to accommodate all of your plating needs. On average our lead times are the following for each department:
Zinc Die Cast Barrel - 3 - 10 days
General Plating - 3 - 7 days

How do I get a copy of NBP's AS9100 Rev. C & ISO 9001Certificate?
See our Quality Page. Please contact us if you preferred it emailed or faxed.

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