Japan Analytical Industry Co., Ltd.
Naoki Oguri Ph. D.
Outgas Anaiysis for Hard Disk Industries
1. Hard Disk Drive and Necessity of its Outgas Analysis
The cross section and the inside view of the hard disk drive (HDD) 3.5" are illustrated in Fig. 5.

Figure 5 Cross section and the inside view of the hard disk drive

Prior to P&T-GC/MS anaiysis, the outgas from HDD, hard disk (HD) or major parts for HDD should becollected into the PAT by using exclusive outgas collector which were manufactured according with size ofdevices.
The collection method and its application are described in this chapter.

The HDD is consisting of a lot of parts as indicated in Fig. 5. The outgas is emitted from the adhesive orcompositional parts in the HDD. There are wrong outgas for HDD, for instance, polydimethyl silixane (DSi),organic phosphorous compounds and/ or higher molecular weight of organic components (HMO). It was told
2

that if DSi presence 1 ppb in 2.5" HDD, the SDSi will be made 0.1 ƒÊm of SiO2 with its oxidation, also organic
phosphorous compounds make solid, after that they will act as the dust. On the other hand, HMO condenses
on the HD after turn off the power supply of HDD, because inside temperature of the HDD goes to lower
temperature, never the condensed HD turn, or the HD will be scratched by the head at next power on time.

From such facts, necessity of the measurement of outgas is needed.

2. Comparison between solvent extraction and P&T method for characterization of the organic
contaminants on the hard disk

The organic contanlinants had been measured by solvent extraction method by using chloromethylene. Figure
6 and Fig. 7 are typical chromatograms obtained by solvent extraction and P&T method respectively.

In the case of solvent extraction method, the lubricant
peak in Fig. 6 is clearly detected at Rt 10 min and RT
17.1 min, however the organic contanlinants are onlydetected two peaks (isopro-pylbenzoate andbutylbenzo-ate) at RT 12.8 min .
On the other hand, in the case of P&T method, thelubricant peak in Fig. 7 is clearly detected at Rt 15 min,also the above mentioned contaminants peak aredetected. More over, Iot of peaks are observed on Fig.
7 than that of Fig. 6.
Those fact told that by use of extraction method is not enough characterization method for the contaminants
analysis. It is considerable to postulate that solvent extraction method can not extract so much contaminants,
i.e. contaminants in the carbon layer (refer to Fig.8) were not extracted, because the contaminants were morestrongly adsorbed in the carbon layer than the extraction power of chloromethylene.

Analytical Condition :Instrument : GC/MS : HP5973, EI, 70 eV; Outgas collector : HD-3.5"; P&T : JHS-100A
Purging : 60ml/min, He; Thermal extraction : 180℃ for 30 min; PAT : Tenax GR;
Oven temp. of JHS-100A : 200℃;

Secondary adsorption tube : Quartz wool, 255℃;

Column : PTE-％, i.d. 0.25 x 30 m, 40℃ (hold 3 min)-280℃, 10℃/min

3. Quantitative Analysis of the Organic Contaminants on the HD

The carbon number 17 to 25 of normal paraffin and 2-ethylhexyl phthalate (DOP) were selected standard
sample in order to get calibration curve. Each 10 mg of their compounds are dissolved into 1,000 ml of hexane.
Figure 9 shows typicai chromatogram of each 10 ng of the standard samples was left on the HD by using
micro syringe. Relative standard deviation (RSD) for eicosane and DOP were measured by 7 continuously
repeated sample injection.

Fig. 9 Typical chromatogram for standard sample obtained from the HD Analyticalconditions are corresponded to Fig. 11.

As a results, RSD of eicosane and DOP were 2.5 and 4.5 respectively.
In the case of outgas anaiysis for HD, the calibration for DOP is quite straight as shown in Fig. 10. However,that of wafer is curved as mentioned latter.
As a conclusion, the organic compound on the HD can be performed by P&T-GC/MS.

Fig. 10 Calibration for eicosane and DOP peak

4. Contaminants Analysis from Carbon Layer for the HD

Before lubricant coating disk at its manufacturing process was set into the model HD-3.5", The disk washeated at 200℃ for 20 min with flowing purge gas 60 ml/min. Outgas from the disk was collected into 3.5 g ofthe Tenax GR packed primary adsorption tube. After pulling out the PAT from HD-3.5", 100 ng of DOP wasinjected into the PAT by using micro-syringe as standard sample injection. After that the PAT was transferred
to JHS-100A, it was then analyzed by P&T-GC/MS.

Fig. 11 outgas chromalogram obtained from the before lubricanl coating disk

1 : Toluene; 2 : Xylene; 3 : Benzaldehyde; 4: Phenol; 5 : 2-Ethylhexanol; 6 : Acetophenone; 7 : Benzoic acid;8 : 2,4-Di-t-octylphcenol; 9 : n-Tetradecanol; 10 : Bis(2-ethylhexyl)phthalate, 11 :Bis(di-n-octyl ) phthalate 100
ng (internal standard)

Analytical Condition:
Instrument : GC/MS : HP5973, EI, 70 eV; Outgas collector : HD-3.5"; P&T : JHS-100A
Purging : 60ml/min, He; Thermal extraction : 255℃ for 20 min; PAT : Tenax GR;
Oven temp. of JHS-100A : 200℃;

Secondary adsorption tube : Quartz wool,Column : DB-2, 0.25ƒÊ
, i.d. 0.25 x 30 m, 40℃ (hold 3 min)-280℃, 10℃/min

Figure 11 shows outgas chromatogram obtained from the before lubricant coating disk. Fundamentally, theorganics compounds on the disk was nothing, however, it is clearly observed on the chromatogram. Totalorganic amount was calculated by the DOP amount of Fig. 10 as 37 ng on the disk.
Toluene and xylene on the chromatogram, they are absorbed airborne compound into the carbon layer after
spattering of the carbon, because spattered carbon has higher adsorption power. 2-ethylhexanol and benzoic
acid may be decomposed compounds from the DOP during the spattering. Also, it is considerable to postulatethat phenol, acetophenone and 2,4-di-t-octylphenol were decomposed compounds from oxy-organic
compounds or cleavaged compounds were reacted each other.