A comparison of convection and condensation Pb-free reflow soldering: convection runs at faster cycle times, while condensation is superior for heavier PCBs.

Ed: For the full article please see circuitsassembly.com/cms/content/view/3204.

Within a range of 3.0 to 4.7% silver and 0.5 to 3.0% copper, the SnAgCu alloy demonstrates a narrow melting temperature Melting temperature may refer to:

Melting temperature, the temperature at which a substance changes from solid to liquid state.
DNA melting temperature, the temperature at which a DNA double helix dissociates into single strands.

range of 216[degrees] to 217[degrees]C.(1) Precise proportioning of the constituents of this alloy does not play a significant role with regard to reliable solder solder (sŏd`ər), metal alloy used in the molten state as a metallic binder. The type of solder to be used is determined by the metals to be united. Soft solders are commonly composed of lead and tin and have low melting points. Hard solders (i. joints, as indicated by a recently published IPC (1) (InterProcess Communication) The exchange of data between one program and another either within the same computer or over a network. It implies a protocol that guarantees a response to a request. study concerning 96.5Sn3.0Ag0.5Cu, 95.5Sn3.8Ag0.7Cu and 95.5Sn4.0Ag0.5Cu solders.(2)

The fundamental upper temperature limit for the process window is dictated by the processing limitations of the utilized materials and components. In particular, moisture-sensitive components are critical. IPC/JEDEC J-STD-020C classifies moisture-sensitive non-hermetic components (MSDs) according to according to
prep.
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

3. package dimensions, among other factors, and restricts the maximum reflow (1) The process of heating and melting the solder that has been screen printed onto a printed circuit board in order to bond chips and other components to the board. Surface mount chips (SMT) use the reflow method. Contrast with wave soldering. See also reflowable text. temperature for package thicknesses of [greater than or equal to]2.5 mm and package volumes of [greater than or equal to]350 square mm to 245[degrees]C. (3) Warm-up and cool-down gradients (+3 K/s, -6 K/s), as well as limiting dwell times above certain temperature levels, represent additional restrictions. Figure 1 shows the working window for the maximum temperature of 245[degrees]C.

[FIGURE 1 OMITTED]

Against this backdrop, the right reflow technology must be selected for the PCB PCB: see polychlorinated biphenyl.

PCB
in full polychlorinated biphenyl

Any of a class of highly stable organic compounds prepared by the reaction of chlorine with biphenyl, a two-ring compound. to be soldered. This article reviews the differences between convection and condensation (vapor phase) soldering.

Dr. Hans Bell

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Title Annotation:	Pb-Free Reflow
Author:	Bell, Hans
Publication:	Circuits Assembly
Date:	May 1, 2006
Words:	239
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