Page 68
www.us-tech.com
October, 2017
EMI Shielding: Improving Sidewall Coverage with
Tilt Spray Coating Continued from page 64
sufficiently covered the corners of the dummy coupons, ensuring a consis- tent shield around the device.
Variable-Pitch Test Results In examining the sprayed shield
coverage on the components, a quick gauge for shield performance can be observed from the surface roughness of sprayed material. Rougher surfaces are more prone to pinhole failures and appear matte. A glossy surface finish generally denotes a more even coating with lower roughness and better con- sistency. In this test, top layer cover- age and appearance was very good. However, sidewall coverage for device pitches below 0.08 in. (2 mm) was poor. It was possible to still see under- lying features from the test vehicle (copper foil lines), indicating incom- plete shield coverage. For testing with the variable-
pitch mounted dummy coupons, two line speeds were run, based on the results from the 0.2 (5 mm) device pitch test results in tests 2 and 3. Sidewall thicknesses were then measured for both sides of each device to examine the effect of the device pitch on the resulting side- wall-to-top-layer thickness ratio. In both cases, the best results were achieved at 0.12 in. (3 mm) pitch between devices and resulted in com- parable sidewall thickness ratios as the results from the 0.2 (5 mm) pitch test. However, results at 0.08 (2 mm) pitch were also notable with a greater than 50 percent sidewall thickness ratio. Below 0.08 in. (2
mm) pitch, the sidewall coverage dropped off significantly, indicating poor coverage and matching with previously observed results. Test results with the Tatsuta
AE5000A-5 material produced less than 15 µm coating thickness with EMI shielding performance, meeting targets at the 1 GHz frequency. Furthermore, a sidewall-to-top-layer thickness ratio greater than 50 per- cent was achieved when using the tilt spray applicator. It is recommended that a minimum of 0.08 in. (2 mm) pitch between devices is used to achieve adequate sidewall coverage, but pitches of 0.12 in. (3 mm) or greater will provide the best cover- age. Further improvements to the coverage ratio may be achieved through fine-tuning of the dispense pattern, line speed and spray-coating parameters. Tilt spray applications provide
performance and coverage results to rival existing EMI shielding. It can now be considered a viable, lower-cost alternative for applying EMI shield- ing to components. Contact: Nordson ASYMTEK,
2747 Loker Avenue West, Carlsbad, CA 92705 % 760-431-1919 E-mail:
akira.morita@nord-
sonasymtek.com Web:
www.nordson.com and Tatsuta Electric Wire & Cable Company Limited, 5201 Great American Parkway, Suite 320, Santa Clara, CA 95054 % 408-850-7166 E-mail:
m-sakaguchi@tatsuta.com Web:
www.tatsuta.com r
See at productronica, Hall A2 Booth 345 Efficient Convection Soldering Electronic & Engineering Materials
with Vacuum and Pyrolysis Continued from previous page
Ask about our IPC-CC-830 / MILil-46058C conformal coatings designed for easy dip or spray application on printed circuit boards and surface mount devices.
age amount used during actual pro- duction. Six sampling points were prepared within the soldering system for the measurement of hydrocarbon compounds: preheating zone 2, pre- heating zone 6, peak zone 2, cooling zone 1, cooling zone 3, and the vacu- um chamber. The highest concentration of
hydrocarbon compounds was meas- ured in preheating zone 2 at 43 ppm. The process temperature of the zone is roughly 302°F (150°C). At this temperature, the chemicals in the solder paste — activators and sol- vents — begin outgassing. Hydrocarbon concentrations in
Learn more about our Conformal Coating Products
preheating zone 6 and peak zone 2 were found to be 32 ppm, although the temperature differs in these zones by 44 K. The lowest residue levels are found in the atmosphere of the soldering system’s cooling tract. The process gas is not only cooled down in the cooling tract, but puri- fied as well.
Purification is accomplished by ® Member 314.621.5700
www.elantas.com/pdg See at productronica, Hall A2 Booth 153
condensing and filtering out extremely fine aerosols at tempera- tures of less than 140°F (60°C). However, this is not very efficient in the hotter zones, because extra ener- gy is required for cooling and subse-
quent heating. Contrary to the expected results, Rehm’s measure- ments showed that the atmosphere evacuated from the vacuum chamber had an average hydrocarbon concen- tration of only 20 ppm. The energy consumption of a
typical soldering system is 16.5 kW. The company found that its new sys- tem consumed 15 kW with the active vacuum process and 13.4 kW without it, representing energy savings of 9 and 18.8 percent, respectively. By building a vacuum chamber
into a convection reflow soldering system, Rehm has created a machine that can meet the growing demand for high-power electronic devices. Its thermal pyrolysis unit is designed to minimize the contamination of the entire system. The company’s simu- lation also provided information about the precise location of the hydrocarbon buildup inside each individual oven zone. With the new oven, Rehm is effectively reducing voiding, maintenance costs and ener- gy consumption. Contact: Rehm Thermal
Systems, LLC, 3080 Northfield Place, Suite 109, Roswell, GA 30076 % 770-442-8913 fax: 770-442-8914 E-mail:
p.handler@rehm-group.com Web:
www.rehm-group.com r
See at productronica, Hall A4 Booth 335
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124
