Copper traces

Liquid metal embrittlement copper traces are present. Results from copper deposits and high temperature conditions. 

Kraay, C.M. (1958). Gold and copper traces in early Greek silver. Archaeometry 1 1-5. 

Anodic stripping voltammetry (ASV) was applied to the determination of copper traces present as Cu(dik)2. The differential pulse technique was used to strip the amalgamated copper from a hanging mercury drop electrode. The experimental variables such as scan rate of electrode potential, deposition potential, deposition time and stirring speed of the solution could be optimized. The linear range of the calibration plot was 0.05-1 (xM and the LOD was 0.014 fiM Cu(II). A method was used for the determination of copper in breast milk and beer as typical examples of application, consisting of minerahzation of the sample, extraction of Cu(II) from the aqueous solution with a 1 M solution of acacH in chloroform and ASV end analysis . 

Petit de Pena, Y., GaUego, M., and Valcarcel, M. (1995). Preconcentration of copper traces on Cgg-C g fullerenes by formation of ion pairs and chelates. Anal. Chem., 67, 2524-9. 

Please note that there must not be any continuity breaks in the copper surface. This does not mean no blemishes or imperfections, but does mean that if you put a multimeter probe on one side of a copper trace there should be a continuity beep when the probe is placed on the other side of the copper trace. Take your time with this step. Keep ironing until... 

When the etching is complete, remove the blue colored resist by scrubbing it off with a Scotch Brite type pad under running water. As you scrub, the copper trace will reveal itself. Remove all the resist and the plates will be done. 

If you are using a drill press without an XY table, this is when you need to have someone hold the lever down while you guide the piece with your hands to route the slots. To rout, simply line up the router bit on the Vs" spaces between the copper traces of the electrode fingers, set up the fence for a cutting guide and push the piece (on a drill press without XY table) along the slot space. 

Sodium-potassium tartrate, 20% solution. Purified by extraction of copper traces with Na-DDTC. 

Note Copper traces can t provide a very low inductance if they are long, however wide they may be. We must remember that though halving the length of any trace does roughly halve its inductance, we have to increase the width of a trace by a factor of 8 to 10 to halve its inductance (see Chapter 6). 

Santelli, E.R., Gallego, M., and Valcarcel, M., 1994, Preconcentration and Atomic Adetermination of Copper Traces in Waters by On-line Adsorbtion-elution on an Activated Carbon Minicolumn, Talanta, 41, 817-823. 

Multilayered LTCC packages were fabricated using the new material. We have confirmed no change in sheet resistance of metallization pattern of copper trace and via, and in hermeticity of the package after reliability tests. 

The lower chart in Hg. 16.1 is used to determine the trace width for various copper thicknesses. For the same cross-sectional area, the width will be smaller for thick copper and wider for thin copper. Continuing with the example, follow the vertical fine down from 200 sq. mil. into the lower chart to the fine labeled (1 oz/fF ) 0.0014 see the discussion of copper thickness in Section 16.4.5. Following the Une across to the axis labeled CONDUCTOR WIDTH IN INCHES shows that the trace should be 0.15 in. wide for a copper trace that is 0.0014 in. thick. If 3 oz. copper were selected, the trace width wonld be approximately 0.05 in. wide rather than 0.15 in. wide for 1 oz. copper. 

Data point L represents an external, 1 oz. copper trace on a 0.03 in. thick PWB. A trace on a thin board runs hotter than a thicker board. The trace in the thin board reaches a 10°C rise at a lower current level than the other boards. Data point O also represents an external, 1 oz. copper trace on a 0.794 mm (0.0312 in.) thick PWB, although it has a 1 oz. copper plane on the backside of the board.The trace on the board with the copper plane can have significantly more current before reaching a 10°C rise than the trace on the board withont the plane due to the heat-spreading capabUity of the plane. 

Copper weights Half-ounce copper traces are similar in temperature rise for the same size cross-sectional area as the 1 oz. traces. An increase in temperature rise of 10 to 15 percent over the 1 oz. traces is observed for 2 oz. traces, and 15 to 20 percent increase for 3 oz. traces for the same cross-sectional area. The higher percentage is for a 45°C rise and the lower percentage is for a 10°C rise. 

Figure 16.9 shows the temperature rise of an internal, 0.010 wide, 1 oz. (0.00135 in.) copper trace (13.5 sq. mil), in a 127 mm (5 in.) wide x 127 mm long x 1.78 mm thick polyimide board, with 1.85 amps. The basehne colnmn represents a trace in a board with no copper planes. The other two colnmns represent the same trace and cnrrent, although now there is a 1 oz. copper plane in the board. The trace is centered in the board and can be above or below the plane. The center colnmn illnstrates the temperature rise if the copper plane is 0.508 mm (0.02 in.)... 

FIGURE 51.11 Soda strawing between copper trace and solder-mask. (courtesy ofIPC)... 

Solder Resist Thickness. When the procurement documentation specifies this thickness, it should be measured at the thinnest area observed between the copper and the surface of the solder resist. This is usually at the corner of the copper trace. 

Flex Circuit without Adhesive Layer Copper Trace... 

There have been several basic technical issues regarding quality assurance for high-density flex circuits, as listed in Table 67.1. Because of the fine circuits and the severe acceptable level of the defects, low-magnification scopes and low-resolution AOI do not work effectively. Magnification of 20 X to 50 X is required for visual inspections of fine circuits, and higher resolutions are required for AOI systems. Low contrast between copper and polyimide base creates another difficulty for traditional AOI equipment. It is not easy for common AOI systems to distinguish the copper traces from the circuits on the other side of a double-sided circuit built on adhesiveless substrate, because the base layer is very transparent and the sensor detects both sides of the circuits as one. 

Feier B, Floner D, Cristea C, Sandulescu R, Geneste F (2013) Development of a novel flow sensor for copper trace analysis by electrochemical reduction of 4-methoxybenzene diazonium salt. Electrochem Commun 31 13-15... 

The copper-free protocols for alkynylation of organyl halides have been used for some applications where copper traces are not welcome. The initial findings came independently from Cassar (submitted January 17, 1975) and Heck (submitted January 8, 1975). ° For example, the alkynylation of haloaryltriazenes proceeds in the absence of copper-catalysts very smoothly (Scheme 5-124). Upon treatment with acids, these alkynyl triazenes cyclize to the corresponding cinnolines. °° ... 

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