Minnitron Ltd

We can supply boards to UL796 & UL94V-0 in accordance with our file number E218872.

The 15 Working day is classed as our "economy" delivery where the best possible price is quoted. If you would like any other delivery please do not hesitate to contact us. We are always making jobs on 24 hour and 2 Working day deliveries.

The above surcharges are to be added only to the board price. Photoplotting charges remain the same.

These are always available in 0.5 ounce or 1 ounce copper thickness. The finished copper thickness i.e. the amount of copper on the tracking surfaces when delivered to the customers is normally calculated as below:-

Therefore a 0.5 ounce base would give a 1.25 ounce finished copper thickness. All we would ask is that you indicate the finished copper thickness and all manufacturing allowances will be made by us.

We recommend that "track and gaps" are kept to a sensible minimum of 6 thou. If this is not possible then our production capabilities can accommodate variations.

We recommend a smallest finished hole size of 0.6mm for vias etc. We can drill down to 0.35mm but it does require smaller stacks and therefore increased cost.

We have in house electrolytic gold plating facilities and can plate edge connectors, whole panels (Maximum size 8" * 8") and selectively plate gold pads.

Standard thickness depend on the application but as a guideline 2.5 microns is used for minimal insertions and 5.0 microns for multiple/repeated insertions.

Photoimageable Solder mask (PI) is a high definition ink used for Surface mount applications and where fine resolutions are required. For most of our larger volume work we use an Ultra violet cured ink (UV) which is very resistant to solder pickup and is quick to process.
We have both inks in the following colours.

The standard colour for the Notation (also known as Ident, Silk screen) is white. We do also have Black and Yellow which can make a nice contrast with different colours of Solder mask.

One of our standard finishes for PTH and Multilayer boards is Lead Free Hot air level. This means that the Solder mask is applied over bare copper. The board is then dipped into a molten alloy of Tin, copper & Nickel, thus coating the exposed copper areas i.e. the pads and holes with a highly solderable finish.

In addition to the HAL finish and to comply with the recent Rohs directive Minnitron Ltd have installed an Immersion Silver line. This finish provides an extremely flat and solderable finish that is completely Lead free. A large investment has been made in this finish to fully automate the process to allow us to offer it as a no additional cost alternative to HAL.

Shelf Life

Under normal storage conditions, a shelf life of 6 - 12 months is expected. The boards should be packaged to protect them from oxidation and stored at room temperature. If boards are removed from the packaging, it is important to re-seal the packaging. (See solderability tests carried out as attached). As a general overview, results are found to be excellent providing the Silver finish is protected from contamination and/or oxidation. Sulphur or Chloride environments will effect the silver surface (resulting in a blackened or yellowed appearance respectively), reducing the solderability.

The Silver finish regularly passes the Siemens Shelf Life Test, (155 deg C, 4 hours), with good subsequent solderability.

Solderability

The Silver finish has excellent solderability characteristics for all applications, including wave and reflow operations. For reflow, it is important that assembly parameters are as per the paste manufacturers recommendations.

In practical terms, solderability will be equivalent to a HASL finished board. It should be noted, however, that as with any other alternative solderable finish to HASL (Electroless Nickel Immersion Gold, Tin, Organic etc.), the surface is more susceptible to surface contamination and fluctuations in assembly parameters. For customers used to assembly using HASL finished boards, it may be necessary to ensure assembly parameters are at optimum, e.g. solder temperatures and/or reflow thermal profiles are correct for the solder and materials being used.

As of 01/01/03 Minnitron Ltd installed an ATG A3 flying probe Bare Board test system. This allows the testing of complex and small volume circuit boards to net-list data. In addition to the flying probe we have a grid tester which involves checking the connectivity of the bare circuit board to a "Golden board". This will indicate the nature and location of the fault for us to easily rectify. On low quantities of boards this process is not normally cost effective but, on larger volumes of boards, or on complex boards where the chance of board faults is increased, (or when a board fault would be difficult and costly to find) BBT is invaluable.