Vapor-phase soldering

The specific thermal differences of the individual mass reflow soldering techniques can be aggravated by the geometrical complexity and profiling of the 3D-MID. 

Contact with the vapor phase uniformly heats the part. 

The vapor condenses, releasing thermal energy that is transmitted to the module. While soldering is in progress the vapor forms a protective barrier, an oxygen-free (inert) gas atmosphere. 

The soft vapor phase (SVP) process maximizes control of heat rise. The temperature gradients can be adapted to the product by control of the immersion depth of the parts for soldering. IBL-Lottechnik GmbH holds patent rights to the SVP process. 

The liquid residues evaporate entirely when the module exits the vapor phase. The module is dry when it exits the soldering oven. 

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CoF is used for the replacement of hydrogen with fluorine in halocarbons (5) for fluorination of xylylalkanes, used in vapor-phase soldering fluxes (6) formation of dibutyl decalins (7) fluorination of alkynes (8) synthesis of unsaturated or partially fluorinated compounds (9—11) and conversion of aromatic compounds to perfluorocycHc compounds (see Fluorine compounds, organic). CoF rarely causes polymerization of hydrocarbons. CoF is also used for the conversion of metal oxides to higher valency metal fluorides, eg, in the assay of uranium ore (12). It is also used in the manufacture of nitrogen fluoride, NF, from ammonia (13). 

Most diallyl phthalate compounds are used in critical electri-c.il/clcctromc applications requiring high reliability under long-term adverse environmental conditions. Compatibility with modern electronic finishing technology, such as vapor phase soldering, is inherent in these materials. 

Vapor-phase soldering of printed circuit Thermal stability, Perfluorophenan-... 

The plateability and hydrolytic stability advantages of polysulfone/ABS blends have been utilized to make selected appliance, plumbing, and sterilizable equipment parts, replacing polycarbonate. Polysulfone/ABS blend has also been evaluated for plateable components of electrical and electronic parts, circuit boards and connectors. However, the lack of adequate heat resistance (DTUL lower than polysulfone) for vapor phase solderability limited its use only in conjunction with other high heat resins as laminates. 

Because flux is such a concern, one contractor is exploring ultrasonic bonding (10) using prepunched aluminum interconnects that are attached to electroplated copper cell metallization with a seam welder. Others are examining fluxless bonding concepts, such as vapor-phase solder reflow. 

Uses Dielec, fluids (transformers, switchgear) heat-transfer fluid for vapor-phase soldering, electronics cooling systems leak testing fluid Manuf./Distrib. ABCR http //www.abcr.de,... 

Toxicology LD50 (oral, rat) >10 g/kg, (IV, mouse) 12 g/kg low toxicity by IV route irritating to eyes, skin, respiratory system may cause wt. loss TSCA listed Hazardous Decomp. Prods. Heated to decomp., emits very toxic fumes of F" and NOx Storage Hygroscopic Uses Heat-transfer fluid for vapor-phase soldering... 

Synonyms PFPE Formula [CF2CFOCF3]x Properties Colorless liq. lowm.w. dens. 1.82-1.84 kg/l (20 C) b.p. 95-240 C Uses Heat-transfer fluid for vapor phase soldering, electronic cooling systems leak testing fluid nonflamm. aircraft/aerospace lubricant... 

These unique combinations of transparency, hydrolytic, and heat resistance of polysulfones would be lost if other polymers are blended. Hence, there has been very little commercial incentive for blends of polysulfone. Nevertheless, in the early days of polysulfone commercialization, some blends with ABS and PET were developed primarily to lower the cost but also to improve selected properties such as plateability or chemical resistance. A PSU/ABS blend (Mindel A) was commercially offered for some time but is now no longer available. Additives such as phenoxy resins, styrene-maleic anhydride copolymers have been claimed to improve the compatibility and weld-line strength of the PSU/ABS blends (Robeson 1985). The blend was evaluated for selected appliance, plumbing, and sterilizable equipment plated parts. This blend lacked the heat resistance needed for the vapor phase solderability in electronic applications. 

Successful performance in vapor-phase soldering environments—419° and 487°E (215° and253°C)... 

The major use of DAPs is in electrical connectors in communications, computer, and aerospace systems. Their high thermal resistance permits their use in vapor-phase soldering. Their other uses are for arc-track-resistant switchgear and television components, circuitboards, and the like. 

Because of safety and environmental concerns and comphance with the Montreal Protocol for the reduction of ozone-depleting chemicals, this soldering technique had fallen out of favor. With the advent of Pb-free soldering, there is increased interest in vapor-phase soldering for SMT applications, but it is likely that it will remain a niche application. Due to its continued diminished status, vapor-phase reflow is covered only briefly. 

Wright, E., Laser vs. Vapor Phase Soldering, Proceedings of the 30th Annual SAMPE Symposium, March 1985, pp. 194-201. 

FIGURE 4.22 Use of workpiece carriers in vapor-phase soldering of MID parts (graphic left courtesy of 2E mechatronic]... 

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