An oxygen index evaluation of flammability on modified epoxy/polyester systems

Latent catalyst effects were investigated to improve the physical properties of halogen-free epoxy molding compounds (EMCs) for semiconductor encapsulation. In this study, biphenyl-type resins were used as the epoxy and hardener resin for halogen-free EMCs to obtain high flame-retardant properties and high filler contents. Latent catalyst effects were examined with two kinds of EMC compositions, halogen-free EMCs and conventional EMC compositions. We used triphenylphosphine-benzoquinone salt (TPP-BQ) as a latent catalyst. Spiral flow and gel time were measured to investigate the change in moldability with the latent catalyst. We measured package fail, moisture absorption, and delamination for reliability evaluation and flexural strength, flexural modulus, and adhesion for mechanical properties to examine latent catalyst effects. An improvement in moldability, reliability, and the mechanical properties were observed in two types of halogen-free EMCs with TPP-BQ as a latent catalyst. These phenomena were seen in conventional EMCs, including o-cresol novolac epoxy resin. The cure kinetics of these systems were investigated by differential scanning calorimetry with an isothermal approach to explain these phenomena. The results indicate that the improvement in moldability in halogen-free EMCs with TPP-BQ was due to the low conversion rate of this system, and the increase in mechanical properties was attributed to the high conversion of curing reaction.

Section: Introductionmentioning

confidence: 99%

Latent catalyst effects in halogen‐free epoxy molding compounds for semiconductor encapsulation

Ryu¹,

Choi²,

Kim³

2005

“…[11][12][13] The LOI values of the composite samples were shown in Table II. Boric acid showed the best flame retardant effect in the glass fiber containing polyester composite.…”

Section: Loi Test Resultsmentioning

confidence: 99%

Investigation of flame retardancy and physical–mechanical properties of zinc borate/boric acid polyester composites

Demirel

Pamuk

Dilsiz

2009

The glass fiber reinforced polyester composite materials were prepared with varying contents of boric acid, zinc borate, and magnesium hydroxide as flame retardants to improve the flame retardancy of the composites. Experimental results showed that boric acid exhibited a good flame retardant effect on the polyester composite. When boric acid content is used as 15 wt %, the Limiting Oxygen Index (LOI) value of the composite reached upto 25.3. The increase in boric acid content from 15 to 30 wt %, the LOI values of composite were enhanced from 25.3 to 34.5 by 9.2 units. The LOI values of the composite samples increased with increasing boric acid content. The smoke density results showed that the addition of glass fiber and flame retardants decreased the smoke density of the unreinforced polyester resin. The mechanical properties of the composites have decreased by the addition of flame retardants. The scanning electron micrographs taken from fracture surfaces were examined. The flame retardants, such as boric acid, were well dispersed in the glass fiber reinforced polyester composites and obviously improved the interfacial interaction between glass fibers and polyester composites.

“…The oxygen concentration of the mixture used in each successive test is increased or reduced by a small amount until the required concentration is reached. 6 According to ASTM D2863-91, vinyl ester resins are classified as rigid samples. In this case, the specimen dimensions should be 6.5 mm in width, 60 mm in length, and 3.0 mm in thickness, with a fired zone of 6.5 mm wide, 40 mm long, and 3.0 mm thick.…”

Section: Oxygen Indexmentioning

confidence: 99%

“…However, for many plastic materials, it is necessary to improve their performance under combustion conditions by incorporating commercially available flame retardants. 6 Some fillers have undesirable effects. For example, high loadings of alumina trihydrate can alter the physical properties of the material, while antimony trioxide is toxic and can increase smoke production.…”

Section: Introductionmentioning

confidence: 99%

Vinyl ester resin modified with silicone‐based additives: II. Flammability properties

Mazali

Felisberti

2005

Silicone-based additives have been used as fire retardants for thermoplastics, presenting the advantages of improving processing and impact resistance of the polymers. In this work we used three different silicone-based additives as modifiers of a thermoset based on a vinyl ester resin. The additives are fine powders made up of about 50 wt % ultra high molecular weight polydimethylsiloxane and 50 wt % silica. The differences between them are the functional groups inserted on the additives and the size and size distribution of the particles. The additives were dispersed in resin containing 35 wt % of styrene. For curing the mixture a conventional catalyst and initiator were used and the reaction was carried out in two ways, differing in the curing temperature, the post curing temperature, and the time, and in the addition of dimethylaniline (DMA) as a promoter of the polyaddition reaction. The samples were characterized by thermogravimetric analyses and swelling experiments. The fire retardances of the samples were evaluated by the determination of the flash-ignition, self-ignition, and pyrolysis temperatures (ASTM D1919 -91a), and of the oxygen index (ASTM D-2863-91). The results obtained showed that the silicone-based additives and the methods used in the preparation of the modified resin influence the flash-ignition, self-ignition, and pyrolysis temperatures, but not the oxygen index. Samples cured by different methods present different network characteristics, which influence their thermal decomposition. The volatile species produced by thermal decomposition may be a combination of inert and active species. The network structure may influence only the inert fraction of the volatiles, not the combustibles. These volatile inert species (smoke-black, water vapor, carbon dioxide, etc.) probably dilute the combustibles in the solid and in the gaseous phase, increasing the flash-ignition temperature of the samples.